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rockbox/firmware/thread.c
Thomas Martitz 240923a801 Rockbox as an application: Commit current Android port progress. 
General state is: Rockbox is usable (plays music, saves configuration, touchscreen works too).
Problems:
 - Playing music in the background (i.e. when switching to another app) doesn't work reliably, but I'm working on that now.
 - no cabbiev2 (only some preliminary files for it), no other default theme.
 - screen flickers sometimes if the updates are too frequent
 - no multi screen apk/package
 - strange behavior when a phone call comes in

The java files (and the eclipse project) resides in android/, which is also supposed to be the build folder.
I've put a small README in there for instructions. There are some steps needed after the make part, which are described there,
and which eclipse mostly handles. But there ought to be some script/makefile rules which do that instead in the future.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@27668 a1c6a512-1295-4272-9138-f99709370657
2010-08-02 20:34:47 +00:00

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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2002 by Ulf Ralberg
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#include "config.h"
#include <stdbool.h>
#include <stdio.h>
#include "thread.h"
#include "panic.h"
#include "system.h"
#include "kernel.h"
#include "cpu.h"
#include "string.h"
#ifdef RB_PROFILE
#include <profile.h>
#endif
/****************************************************************************
* ATTENTION!! *
* See notes below on implementing processor-specific portions! *
***************************************************************************/
/* Define THREAD_EXTRA_CHECKS as 1 to enable additional state checks */
#ifdef DEBUG
#define THREAD_EXTRA_CHECKS 1 /* Always 1 for DEBUG */
#else
#define THREAD_EXTRA_CHECKS 0
#endif
/**
* General locking order to guarantee progress. Order must be observed but
* all stages are not nescessarily obligatory. Going from 1) to 3) is
* perfectly legal.
*
* 1) IRQ
* This is first because of the likelyhood of having an interrupt occur that
* also accesses one of the objects farther down the list. Any non-blocking
* synchronization done may already have a lock on something during normal
* execution and if an interrupt handler running on the same processor as
* the one that has the resource locked were to attempt to access the
* resource, the interrupt handler would wait forever waiting for an unlock
* that will never happen. There is no danger if the interrupt occurs on
* a different processor because the one that has the lock will eventually
* unlock and the other processor's handler may proceed at that time. Not
* nescessary when the resource in question is definitely not available to
* interrupt handlers.
*
* 2) Kernel Object
* 1) May be needed beforehand if the kernel object allows dual-use such as
* event queues. The kernel object must have a scheme to protect itself from
* access by another processor and is responsible for serializing the calls
* to block_thread(_w_tmo) and wakeup_thread both to themselves and to each
* other. Objects' queues are also protected here.
*
* 3) Thread Slot
* This locks access to the thread's slot such that its state cannot be
* altered by another processor when a state change is in progress such as
* when it is in the process of going on a blocked list. An attempt to wake
* a thread while it is still blocking will likely desync its state with
* the other resources used for that state.
*
* 4) Core Lists
* These lists are specific to a particular processor core and are accessible
* by all processor cores and interrupt handlers. The running (rtr) list is
* the prime example where a thread may be added by any means.
*/
/*---------------------------------------------------------------------------
* Processor specific: core_sleep/core_wake/misc. notes
*
* ARM notes:
* FIQ is not dealt with by the scheduler code and is simply restored if it
* must by masked for some reason - because threading modifies a register
* that FIQ may also modify and there's no way to accomplish it atomically.
* s3c2440 is such a case.
*
* Audio interrupts are generally treated at a higher priority than others
* usage of scheduler code with interrupts higher than HIGHEST_IRQ_LEVEL
* are not in general safe. Special cases may be constructed on a per-
* source basis and blocking operations are not available.
*
* core_sleep procedure to implement for any CPU to ensure an asychronous
* wakup never results in requiring a wait until the next tick (up to
* 10000uS!). May require assembly and careful instruction ordering.
*
* 1) On multicore, stay awake if directed to do so by another. If so, goto
* step 4.
* 2) If processor requires, atomically reenable interrupts and perform step
* 3.
* 3) Sleep the CPU core. If wakeup itself enables interrupts (stop #0x2000
* on Coldfire) goto step 5.
* 4) Enable interrupts.
* 5) Exit procedure.
*
* core_wake and multprocessor notes for sleep/wake coordination:
* If possible, to wake up another processor, the forcing of an interrupt on
* the woken core by the waker core is the easiest way to ensure a non-
* delayed wake and immediate execution of any woken threads. If that isn't
* available then some careful non-blocking synchonization is needed (as on
* PP targets at the moment).
*---------------------------------------------------------------------------
*/
/* Cast to the the machine pointer size, whose size could be < 4 or > 32
* (someday :). */
#define DEADBEEF ((uintptr_t)0xdeadbeefdeadbeefull)
static struct core_entry cores[NUM_CORES] IBSS_ATTR;
struct thread_entry threads[MAXTHREADS] IBSS_ATTR;
static const char main_thread_name[] = "main";
#if (CONFIG_PLATFORM & PLATFORM_NATIVE)
extern uintptr_t stackbegin[];
extern uintptr_t stackend[];
#else
extern uintptr_t *stackbegin;
extern uintptr_t *stackend;
#endif
static inline void core_sleep(IF_COP_VOID(unsigned int core))
__attribute__((always_inline));
void check_tmo_threads(void)
__attribute__((noinline));
static inline void block_thread_on_l(struct thread_entry *thread, unsigned state)
__attribute__((always_inline));
static void add_to_list_tmo(struct thread_entry *thread)
__attribute__((noinline));
static void core_schedule_wakeup(struct thread_entry *thread)
__attribute__((noinline));
#if NUM_CORES > 1
static inline void run_blocking_ops(
unsigned int core, struct thread_entry *thread)
__attribute__((always_inline));
#endif
static void thread_stkov(struct thread_entry *thread)
__attribute__((noinline));
static inline void store_context(void* addr)
__attribute__((always_inline));
static inline void load_context(const void* addr)
__attribute__((always_inline));
#if NUM_CORES > 1
static void thread_final_exit_do(struct thread_entry *current)
__attribute__((noinline, noreturn, used));
#else
static inline void thread_final_exit(struct thread_entry *current)
__attribute__((always_inline, noreturn));
#endif
void switch_thread(void)
__attribute__((noinline));
/****************************************************************************
* Processor-specific section - include necessary core support
*/
#if defined(ANDROID)
#include "thread-android-arm.c"
#elif defined(CPU_ARM)
#include "thread-arm.c"
#if defined (CPU_PP)
#include "thread-pp.c"
#endif /* CPU_PP */
#elif defined(CPU_COLDFIRE)
#include "thread-coldfire.c"
#elif CONFIG_CPU == SH7034
#include "thread-sh.c"
#elif defined(CPU_MIPS) && CPU_MIPS == 32
#include "thread-mips32.c"
#else
/* Wouldn't compile anyway */
#error Processor not implemented.
#endif /* CONFIG_CPU == */
#ifndef IF_NO_SKIP_YIELD
#define IF_NO_SKIP_YIELD(...)
#endif
/*
* End Processor-specific section
***************************************************************************/
#if THREAD_EXTRA_CHECKS
static void thread_panicf(const char *msg, struct thread_entry *thread)
{
IF_COP( const unsigned int core = thread->core; )
static char name[32];
thread_get_name(name, 32, thread);
panicf ("%s %s" IF_COP(" (%d)"), msg, name IF_COP(, core));
}
static void thread_stkov(struct thread_entry *thread)
{
thread_panicf("Stkov", thread);
}
#define THREAD_PANICF(msg, thread) \
thread_panicf(msg, thread)
#define THREAD_ASSERT(exp, msg, thread) \
({ if (!({ exp; })) thread_panicf((msg), (thread)); })
#else
static void thread_stkov(struct thread_entry *thread)
{
IF_COP( const unsigned int core = thread->core; )
static char name[32];
thread_get_name(name, 32, thread);
panicf("Stkov %s" IF_COP(" (%d)"), name IF_COP(, core));
}
#define THREAD_PANICF(msg, thread)
#define THREAD_ASSERT(exp, msg, thread)
#endif /* THREAD_EXTRA_CHECKS */
/* Thread locking */
#if NUM_CORES > 1
#define LOCK_THREAD(thread) \
({ corelock_lock(&(thread)->slot_cl); })
#define TRY_LOCK_THREAD(thread) \
({ corelock_try_lock(&(thread)->slot_cl); })
#define UNLOCK_THREAD(thread) \
({ corelock_unlock(&(thread)->slot_cl); })
#define UNLOCK_THREAD_AT_TASK_SWITCH(thread) \
({ unsigned int _core = (thread)->core; \
cores[_core].blk_ops.flags |= TBOP_UNLOCK_CORELOCK; \
cores[_core].blk_ops.cl_p = &(thread)->slot_cl; })
#else
#define LOCK_THREAD(thread) \
({ })
#define TRY_LOCK_THREAD(thread) \
({ })
#define UNLOCK_THREAD(thread) \
({ })
#define UNLOCK_THREAD_AT_TASK_SWITCH(thread) \
({ })
#endif
/* RTR list */
#define RTR_LOCK(core) \
({ corelock_lock(&cores[core].rtr_cl); })
#define RTR_UNLOCK(core) \
({ corelock_unlock(&cores[core].rtr_cl); })
#ifdef HAVE_PRIORITY_SCHEDULING
#define rtr_add_entry(core, priority) \
prio_add_entry(&cores[core].rtr, (priority))
#define rtr_subtract_entry(core, priority) \
prio_subtract_entry(&cores[core].rtr, (priority))
#define rtr_move_entry(core, from, to) \
prio_move_entry(&cores[core].rtr, (from), (to))
#else
#define rtr_add_entry(core, priority)
#define rtr_add_entry_inl(core, priority)
#define rtr_subtract_entry(core, priority)
#define rtr_subtract_entry_inl(core, priotity)
#define rtr_move_entry(core, from, to)
#define rtr_move_entry_inl(core, from, to)
#endif
/*---------------------------------------------------------------------------
* Thread list structure - circular:
* +------------------------------+
* | |
* +--+---+<-+---+<-+---+<-+---+<-+
* Head->| T | | T | | T | | T |
* +->+---+->+---+->+---+->+---+--+
* | |
* +------------------------------+
*---------------------------------------------------------------------------
*/
/*---------------------------------------------------------------------------
* Adds a thread to a list of threads using "insert last". Uses the "l"
* links.
*---------------------------------------------------------------------------
*/
static void add_to_list_l(struct thread_entry **list,
struct thread_entry *thread)
{
struct thread_entry *l = *list;
if (l == NULL)
{
/* Insert into unoccupied list */
thread->l.prev = thread;
thread->l.next = thread;
*list = thread;
return;
}
/* Insert last */
thread->l.prev = l->l.prev;
thread->l.next = l;
l->l.prev->l.next = thread;
l->l.prev = thread;
}
/*---------------------------------------------------------------------------
* Removes a thread from a list of threads. Uses the "l" links.
*---------------------------------------------------------------------------
*/
static void remove_from_list_l(struct thread_entry **list,
struct thread_entry *thread)
{
struct thread_entry *prev, *next;
next = thread->l.next;
if (thread == next)
{
/* The only item */
*list = NULL;
return;
}
if (thread == *list)
{
/* List becomes next item */
*list = next;
}
prev = thread->l.prev;
/* Fix links to jump over the removed entry. */
next->l.prev = prev;
prev->l.next = next;
}
/*---------------------------------------------------------------------------
* Timeout list structure - circular reverse (to make "remove item" O(1)),
* NULL-terminated forward (to ease the far more common forward traversal):
* +------------------------------+
* | |
* +--+---+<-+---+<-+---+<-+---+<-+
* Head->| T | | T | | T | | T |
* +---+->+---+->+---+->+---+-X
*---------------------------------------------------------------------------
*/
/*---------------------------------------------------------------------------
* Add a thread from the core's timout list by linking the pointers in its
* tmo structure.
*---------------------------------------------------------------------------
*/
static void add_to_list_tmo(struct thread_entry *thread)
{
struct thread_entry *tmo = cores[IF_COP_CORE(thread->core)].timeout;
THREAD_ASSERT(thread->tmo.prev == NULL,
"add_to_list_tmo->already listed", thread);
thread->tmo.next = NULL;
if (tmo == NULL)
{
/* Insert into unoccupied list */
thread->tmo.prev = thread;
cores[IF_COP_CORE(thread->core)].timeout = thread;
return;
}
/* Insert Last */
thread->tmo.prev = tmo->tmo.prev;
tmo->tmo.prev->tmo.next = thread;
tmo->tmo.prev = thread;
}
/*---------------------------------------------------------------------------
* Remove a thread from the core's timout list by unlinking the pointers in
* its tmo structure. Sets thread->tmo.prev to NULL to indicate the timeout
* is cancelled.
*---------------------------------------------------------------------------
*/
static void remove_from_list_tmo(struct thread_entry *thread)
{
struct thread_entry **list = &cores[IF_COP_CORE(thread->core)].timeout;
struct thread_entry *prev = thread->tmo.prev;
struct thread_entry *next = thread->tmo.next;
THREAD_ASSERT(prev != NULL, "remove_from_list_tmo->not listed", thread);
if (next != NULL)
next->tmo.prev = prev;
if (thread == *list)
{
/* List becomes next item and empty if next == NULL */
*list = next;
/* Mark as unlisted */
thread->tmo.prev = NULL;
}
else
{
if (next == NULL)
(*list)->tmo.prev = prev;
prev->tmo.next = next;
/* Mark as unlisted */
thread->tmo.prev = NULL;
}
}
#ifdef HAVE_PRIORITY_SCHEDULING
/*---------------------------------------------------------------------------
* Priority distribution structure (one category for each possible priority):
*
* +----+----+----+ ... +-----+
* hist: | F0 | F1 | F2 | | F31 |
* +----+----+----+ ... +-----+
* mask: | b0 | b1 | b2 | | b31 |
* +----+----+----+ ... +-----+
*
* F = count of threads at priority category n (frequency)
* b = bitmask of non-zero priority categories (occupancy)
*
* / if H[n] != 0 : 1
* b[n] = |
* \ else : 0
*
*---------------------------------------------------------------------------
* Basic priority inheritance priotocol (PIP):
*
* Mn = mutex n, Tn = thread n
*
* A lower priority thread inherits the priority of the highest priority
* thread blocked waiting for it to complete an action (such as release a
* mutex or respond to a message via queue_send):
*
* 1) T2->M1->T1
*
* T1 owns M1, T2 is waiting for M1 to realease M1. If T2 has a higher
* priority than T1 then T1 inherits the priority of T2.
*
* 2) T3
* \/
* T2->M1->T1
*
* Situation is like 1) but T2 and T3 are both queued waiting for M1 and so
* T1 inherits the higher of T2 and T3.
*
* 3) T3->M2->T2->M1->T1
*
* T1 owns M1, T2 owns M2. If T3 has a higher priority than both T1 and T2,
* then T1 inherits the priority of T3 through T2.
*
* Blocking chains can grow arbitrarily complex (though it's best that they
* not form at all very often :) and build-up from these units.
*---------------------------------------------------------------------------
*/
/*---------------------------------------------------------------------------
* Increment frequency at category "priority"
*---------------------------------------------------------------------------
*/
static inline unsigned int prio_add_entry(
struct priority_distribution *pd, int priority)
{
unsigned int count;
/* Enough size/instruction count difference for ARM makes it worth it to
* use different code (192 bytes for ARM). Only thing better is ASM. */
#ifdef CPU_ARM
count = pd->hist[priority];
if (++count == 1)
pd->mask |= 1 << priority;
pd->hist[priority] = count;
#else /* This one's better for Coldfire */
if ((count = ++pd->hist[priority]) == 1)
pd->mask |= 1 << priority;
#endif
return count;
}
/*---------------------------------------------------------------------------
* Decrement frequency at category "priority"
*---------------------------------------------------------------------------
*/
static inline unsigned int prio_subtract_entry(
struct priority_distribution *pd, int priority)
{
unsigned int count;
#ifdef CPU_ARM
count = pd->hist[priority];
if (--count == 0)
pd->mask &= ~(1 << priority);
pd->hist[priority] = count;
#else
if ((count = --pd->hist[priority]) == 0)
pd->mask &= ~(1 << priority);
#endif
return count;
}
/*---------------------------------------------------------------------------
* Remove from one category and add to another
*---------------------------------------------------------------------------
*/
static inline void prio_move_entry(
struct priority_distribution *pd, int from, int to)
{
uint32_t mask = pd->mask;
#ifdef CPU_ARM
unsigned int count;
count = pd->hist[from];
if (--count == 0)
mask &= ~(1 << from);
pd->hist[from] = count;
count = pd->hist[to];
if (++count == 1)
mask |= 1 << to;
pd->hist[to] = count;
#else
if (--pd->hist[from] == 0)
mask &= ~(1 << from);
if (++pd->hist[to] == 1)
mask |= 1 << to;
#endif
pd->mask = mask;
}
/*---------------------------------------------------------------------------
* Change the priority and rtr entry for a running thread
*---------------------------------------------------------------------------
*/
static inline void set_running_thread_priority(
struct thread_entry *thread, int priority)
{
const unsigned int core = IF_COP_CORE(thread->core);
RTR_LOCK(core);
rtr_move_entry(core, thread->priority, priority);
thread->priority = priority;
RTR_UNLOCK(core);
}
/*---------------------------------------------------------------------------
* Finds the highest priority thread in a list of threads. If the list is
* empty, the PRIORITY_IDLE is returned.
*
* It is possible to use the struct priority_distribution within an object
* instead of scanning the remaining threads in the list but as a compromise,
* the resulting per-object memory overhead is saved at a slight speed
* penalty under high contention.
*---------------------------------------------------------------------------
*/
static int find_highest_priority_in_list_l(
struct thread_entry * const thread)
{
if (LIKELY(thread != NULL))
{
/* Go though list until the ending up at the initial thread */
int highest_priority = thread->priority;
struct thread_entry *curr = thread;
do
{
int priority = curr->priority;
if (priority < highest_priority)
highest_priority = priority;
curr = curr->l.next;
}
while (curr != thread);
return highest_priority;
}
return PRIORITY_IDLE;
}
/*---------------------------------------------------------------------------
* Register priority with blocking system and bubble it down the chain if
* any until we reach the end or something is already equal or higher.
*
* NOTE: A simultaneous circular wait could spin deadlock on multiprocessor
* targets but that same action also guarantees a circular block anyway and
* those are prevented, right? :-)
*---------------------------------------------------------------------------
*/
static struct thread_entry *
blocker_inherit_priority(struct thread_entry *current)
{
const int priority = current->priority;
struct blocker *bl = current->blocker;
struct thread_entry * const tstart = current;
struct thread_entry *bl_t = bl->thread;
/* Blocker cannot change since the object protection is held */
LOCK_THREAD(bl_t);
for (;;)
{
struct thread_entry *next;
int bl_pr = bl->priority;
if (priority >= bl_pr)
break; /* Object priority already high enough */
bl->priority = priority;
/* Add this one */
prio_add_entry(&bl_t->pdist, priority);
if (bl_pr < PRIORITY_IDLE)
{
/* Not first waiter - subtract old one */
prio_subtract_entry(&bl_t->pdist, bl_pr);
}
if (priority >= bl_t->priority)
break; /* Thread priority high enough */
if (bl_t->state == STATE_RUNNING)
{
/* Blocking thread is a running thread therefore there are no
* further blockers. Change the "run queue" on which it
* resides. */
set_running_thread_priority(bl_t, priority);
break;
}
bl_t->priority = priority;
/* If blocking thread has a blocker, apply transitive inheritance */
bl = bl_t->blocker;
if (bl == NULL)
break; /* End of chain or object doesn't support inheritance */
next = bl->thread;
if (UNLIKELY(next == tstart))
break; /* Full-circle - deadlock! */
UNLOCK_THREAD(current);
#if NUM_CORES > 1
for (;;)
{
LOCK_THREAD(next);
/* Blocker could change - retest condition */
if (LIKELY(bl->thread == next))
break;
UNLOCK_THREAD(next);
next = bl->thread;
}
#endif
current = bl_t;
bl_t = next;
}
UNLOCK_THREAD(bl_t);
return current;
}
/*---------------------------------------------------------------------------
* Readjust priorities when waking a thread blocked waiting for another
* in essence "releasing" the thread's effect on the object owner. Can be
* performed from any context.
*---------------------------------------------------------------------------
*/
struct thread_entry *
wakeup_priority_protocol_release(struct thread_entry *thread)
{
const int priority = thread->priority;
struct blocker *bl = thread->blocker;
struct thread_entry * const tstart = thread;
struct thread_entry *bl_t = bl->thread;
/* Blocker cannot change since object will be locked */
LOCK_THREAD(bl_t);
thread->blocker = NULL; /* Thread not blocked */
for (;;)
{
struct thread_entry *next;
int bl_pr = bl->priority;
if (priority > bl_pr)
break; /* Object priority higher */
next = *thread->bqp;
if (next == NULL)
{
/* No more threads in queue */
prio_subtract_entry(&bl_t->pdist, bl_pr);
bl->priority = PRIORITY_IDLE;
}
else
{
/* Check list for highest remaining priority */
int queue_pr = find_highest_priority_in_list_l(next);
if (queue_pr == bl_pr)
break; /* Object priority not changing */
/* Change queue priority */
prio_move_entry(&bl_t->pdist, bl_pr, queue_pr);
bl->priority = queue_pr;
}
if (bl_pr > bl_t->priority)
break; /* thread priority is higher */
bl_pr = find_first_set_bit(bl_t->pdist.mask);
if (bl_pr == bl_t->priority)
break; /* Thread priority not changing */
if (bl_t->state == STATE_RUNNING)
{
/* No further blockers */
set_running_thread_priority(bl_t, bl_pr);
break;
}
bl_t->priority = bl_pr;
/* If blocking thread has a blocker, apply transitive inheritance */
bl = bl_t->blocker;
if (bl == NULL)
break; /* End of chain or object doesn't support inheritance */
next = bl->thread;
if (UNLIKELY(next == tstart))
break; /* Full-circle - deadlock! */
UNLOCK_THREAD(thread);
#if NUM_CORES > 1
for (;;)
{
LOCK_THREAD(next);
/* Blocker could change - retest condition */
if (LIKELY(bl->thread == next))
break;
UNLOCK_THREAD(next);
next = bl->thread;
}
#endif
thread = bl_t;
bl_t = next;
}
UNLOCK_THREAD(bl_t);
#if NUM_CORES > 1
if (UNLIKELY(thread != tstart))
{
/* Relock original if it changed */
LOCK_THREAD(tstart);
}
#endif
return cores[CURRENT_CORE].running;
}
/*---------------------------------------------------------------------------
* Transfer ownership to a thread waiting for an objects and transfer
* inherited priority boost from other waiters. This algorithm knows that
* blocking chains may only unblock from the very end.
*
* Only the owning thread itself may call this and so the assumption that
* it is the running thread is made.
*---------------------------------------------------------------------------
*/
struct thread_entry *
wakeup_priority_protocol_transfer(struct thread_entry *thread)
{
/* Waking thread inherits priority boost from object owner */
struct blocker *bl = thread->blocker;
struct thread_entry *bl_t = bl->thread;
struct thread_entry *next;
int bl_pr;
THREAD_ASSERT(cores[CURRENT_CORE].running == bl_t,
"UPPT->wrong thread", cores[CURRENT_CORE].running);
LOCK_THREAD(bl_t);
bl_pr = bl->priority;
/* Remove the object's boost from the owning thread */
if (prio_subtract_entry(&bl_t->pdist, bl_pr) == 0 &&
bl_pr <= bl_t->priority)
{
/* No more threads at this priority are waiting and the old level is
* at least the thread level */
int priority = find_first_set_bit(bl_t->pdist.mask);
if (priority != bl_t->priority)
{
/* Adjust this thread's priority */
set_running_thread_priority(bl_t, priority);
}
}
next = *thread->bqp;
if (LIKELY(next == NULL))
{
/* Expected shortcut - no more waiters */
bl_pr = PRIORITY_IDLE;
}
else
{
if (thread->priority <= bl_pr)
{
/* Need to scan threads remaining in queue */
bl_pr = find_highest_priority_in_list_l(next);
}
if (prio_add_entry(&thread->pdist, bl_pr) == 1 &&
bl_pr < thread->priority)
{
/* Thread priority must be raised */
thread->priority = bl_pr;
}
}
bl->thread = thread; /* This thread pwns */
bl->priority = bl_pr; /* Save highest blocked priority */
thread->blocker = NULL; /* Thread not blocked */
UNLOCK_THREAD(bl_t);
return bl_t;
}
/*---------------------------------------------------------------------------
* No threads must be blocked waiting for this thread except for it to exit.
* The alternative is more elaborate cleanup and object registration code.
* Check this for risk of silent data corruption when objects with
* inheritable blocking are abandoned by the owner - not precise but may
* catch something.
*---------------------------------------------------------------------------
*/
static void __attribute__((noinline)) check_for_obj_waiters(
const char *function, struct thread_entry *thread)
{
/* Only one bit in the mask should be set with a frequency on 1 which
* represents the thread's own base priority */
uint32_t mask = thread->pdist.mask;
if ((mask & (mask - 1)) != 0 ||
thread->pdist.hist[find_first_set_bit(mask)] > 1)
{
unsigned char name[32];
thread_get_name(name, 32, thread);
panicf("%s->%s with obj. waiters", function, name);
}
}
#endif /* HAVE_PRIORITY_SCHEDULING */
/*---------------------------------------------------------------------------
* Move a thread back to a running state on its core.
*---------------------------------------------------------------------------
*/
static void core_schedule_wakeup(struct thread_entry *thread)
{
const unsigned int core = IF_COP_CORE(thread->core);
RTR_LOCK(core);
thread->state = STATE_RUNNING;
add_to_list_l(&cores[core].running, thread);
rtr_add_entry(core, thread->priority);
RTR_UNLOCK(core);
#if NUM_CORES > 1
if (core != CURRENT_CORE)
core_wake(core);
#endif
}
/*---------------------------------------------------------------------------
* Check the core's timeout list when at least one thread is due to wake.
* Filtering for the condition is done before making the call. Resets the
* tick when the next check will occur.
*---------------------------------------------------------------------------
*/
void check_tmo_threads(void)
{
const unsigned int core = CURRENT_CORE;
const long tick = current_tick; /* snapshot the current tick */
long next_tmo_check = tick + 60*HZ; /* minimum duration: once/minute */
struct thread_entry *next = cores[core].timeout;
/* If there are no processes waiting for a timeout, just keep the check
tick from falling into the past. */
/* Break the loop once we have walked through the list of all
* sleeping processes or have removed them all. */
while (next != NULL)
{
/* Check sleeping threads. Allow interrupts between checks. */
enable_irq();
struct thread_entry *curr = next;
next = curr->tmo.next;
/* Lock thread slot against explicit wakeup */
disable_irq();
LOCK_THREAD(curr);
unsigned state = curr->state;
if (state < TIMEOUT_STATE_FIRST)
{
/* Cleanup threads no longer on a timeout but still on the
* list. */
remove_from_list_tmo(curr);
}
else if (LIKELY(TIME_BEFORE(tick, curr->tmo_tick)))
{
/* Timeout still pending - this will be the usual case */
if (TIME_BEFORE(curr->tmo_tick, next_tmo_check))
{
/* Earliest timeout found so far - move the next check up
to its time */
next_tmo_check = curr->tmo_tick;
}
}
else
{
/* Sleep timeout has been reached so bring the thread back to
* life again. */
if (state == STATE_BLOCKED_W_TMO)
{
#if NUM_CORES > 1
/* Lock the waiting thread's kernel object */
struct corelock *ocl = curr->obj_cl;
if (UNLIKELY(corelock_try_lock(ocl) == 0))
{
/* Need to retry in the correct order though the need is
* unlikely */
UNLOCK_THREAD(curr);
corelock_lock(ocl);
LOCK_THREAD(curr);
if (UNLIKELY(curr->state != STATE_BLOCKED_W_TMO))
{
/* Thread was woken or removed explicitely while slot
* was unlocked */
corelock_unlock(ocl);
remove_from_list_tmo(curr);
UNLOCK_THREAD(curr);
continue;
}
}
#endif /* NUM_CORES */
remove_from_list_l(curr->bqp, curr);
#ifdef HAVE_WAKEUP_EXT_CB
if (curr->wakeup_ext_cb != NULL)
curr->wakeup_ext_cb(curr);
#endif
#ifdef HAVE_PRIORITY_SCHEDULING
if (curr->blocker != NULL)
wakeup_priority_protocol_release(curr);
#endif
corelock_unlock(ocl);
}
/* else state == STATE_SLEEPING */
remove_from_list_tmo(curr);
RTR_LOCK(core);
curr->state = STATE_RUNNING;
add_to_list_l(&cores[core].running, curr);
rtr_add_entry(core, curr->priority);
RTR_UNLOCK(core);
}
UNLOCK_THREAD(curr);
}
cores[core].next_tmo_check = next_tmo_check;
}
/*---------------------------------------------------------------------------
* Performs operations that must be done before blocking a thread but after
* the state is saved.
*---------------------------------------------------------------------------
*/
#if NUM_CORES > 1
static inline void run_blocking_ops(
unsigned int core, struct thread_entry *thread)
{
struct thread_blk_ops *ops = &cores[core].blk_ops;
const unsigned flags = ops->flags;
if (LIKELY(flags == TBOP_CLEAR))
return;
switch (flags)
{
case TBOP_SWITCH_CORE:
core_switch_blk_op(core, thread);
/* Fall-through */
case TBOP_UNLOCK_CORELOCK:
corelock_unlock(ops->cl_p);
break;
}
ops->flags = TBOP_CLEAR;
}
#endif /* NUM_CORES > 1 */
#ifdef RB_PROFILE
void profile_thread(void)
{
profstart(cores[CURRENT_CORE].running - threads);
}
#endif
/*---------------------------------------------------------------------------
* Prepares a thread to block on an object's list and/or for a specified
* duration - expects object and slot to be appropriately locked if needed
* and interrupts to be masked.
*---------------------------------------------------------------------------
*/
static inline void block_thread_on_l(struct thread_entry *thread,
unsigned state)
{
/* If inlined, unreachable branches will be pruned with no size penalty
because state is passed as a constant parameter. */
const unsigned int core = IF_COP_CORE(thread->core);
/* Remove the thread from the list of running threads. */
RTR_LOCK(core);
remove_from_list_l(&cores[core].running, thread);
rtr_subtract_entry(core, thread->priority);
RTR_UNLOCK(core);
/* Add a timeout to the block if not infinite */
switch (state)
{
case STATE_BLOCKED:
case STATE_BLOCKED_W_TMO:
/* Put the thread into a new list of inactive threads. */
add_to_list_l(thread->bqp, thread);
if (state == STATE_BLOCKED)
break;
/* Fall-through */
case STATE_SLEEPING:
/* If this thread times out sooner than any other thread, update
next_tmo_check to its timeout */
if (TIME_BEFORE(thread->tmo_tick, cores[core].next_tmo_check))
{
cores[core].next_tmo_check = thread->tmo_tick;
}
if (thread->tmo.prev == NULL)
{
add_to_list_tmo(thread);
}
/* else thread was never removed from list - just keep it there */
break;
}
/* Remember the the next thread about to block. */
cores[core].block_task = thread;
/* Report new state. */
thread->state = state;
}
/*---------------------------------------------------------------------------
* Switch thread in round robin fashion for any given priority. Any thread
* that removed itself from the running list first must specify itself in
* the paramter.
*
* INTERNAL: Intended for use by kernel and not for programs.
*---------------------------------------------------------------------------
*/
void switch_thread(void)
{
const unsigned int core = CURRENT_CORE;
struct thread_entry *block = cores[core].block_task;
struct thread_entry *thread = cores[core].running;
/* Get context to save - next thread to run is unknown until all wakeups
* are evaluated */
if (block != NULL)
{
cores[core].block_task = NULL;
#if NUM_CORES > 1
if (UNLIKELY(thread == block))
{
/* This was the last thread running and another core woke us before
* reaching here. Force next thread selection to give tmo threads or
* other threads woken before this block a first chance. */
block = NULL;
}
else
#endif
{
/* Blocking task is the old one */
thread = block;
}
}
#ifdef RB_PROFILE
profile_thread_stopped(thread->id & THREAD_ID_SLOT_MASK);
#endif
/* Begin task switching by saving our current context so that we can
* restore the state of the current thread later to the point prior
* to this call. */
store_context(&thread->context);
/* Check if the current thread stack is overflown */
if (UNLIKELY(thread->stack[0] != DEADBEEF) && thread->stack_size > 0)
thread_stkov(thread);
#if NUM_CORES > 1
/* Run any blocking operations requested before switching/sleeping */
run_blocking_ops(core, thread);
#endif
#ifdef HAVE_PRIORITY_SCHEDULING
IF_NO_SKIP_YIELD( if (thread->skip_count != -1) )
/* Reset the value of thread's skip count */
thread->skip_count = 0;
#endif
for (;;)
{
/* If there are threads on a timeout and the earliest wakeup is due,
* check the list and wake any threads that need to start running
* again. */
if (!TIME_BEFORE(current_tick, cores[core].next_tmo_check))
{
check_tmo_threads();
}
disable_irq();
RTR_LOCK(core);
thread = cores[core].running;
if (UNLIKELY(thread == NULL))
{
/* Enter sleep mode to reduce power usage - woken up on interrupt
* or wakeup request from another core - expected to enable
* interrupts. */
RTR_UNLOCK(core);
core_sleep(IF_COP(core));
}
else
{
#ifdef HAVE_PRIORITY_SCHEDULING
/* Select the new task based on priorities and the last time a
* process got CPU time relative to the highest priority runnable
* task. */
struct priority_distribution *pd = &cores[core].rtr;
int max = find_first_set_bit(pd->mask);
if (block == NULL)
{
/* Not switching on a block, tentatively select next thread */
thread = thread->l.next;
}
for (;;)
{
int priority = thread->priority;
int diff;
/* This ridiculously simple method of aging seems to work
* suspiciously well. It does tend to reward CPU hogs (under
* yielding) but that's generally not desirable at all. On
* the plus side, it, relatively to other threads, penalizes
* excess yielding which is good if some high priority thread
* is performing no useful work such as polling for a device
* to be ready. Of course, aging is only employed when higher
* and lower priority threads are runnable. The highest
* priority runnable thread(s) are never skipped unless a
* lower-priority process has aged sufficiently. Priorities
* of REALTIME class are run strictly according to priority
* thus are not subject to switchout due to lower-priority
* processes aging; they must give up the processor by going
* off the run list. */
if (LIKELY(priority <= max) ||
IF_NO_SKIP_YIELD( thread->skip_count == -1 || )
(priority > PRIORITY_REALTIME &&
(diff = priority - max,
++thread->skip_count > diff*diff)))
{
cores[core].running = thread;
break;
}
thread = thread->l.next;
}
#else
/* Without priority use a simple FCFS algorithm */
if (block == NULL)
{
/* Not switching on a block, select next thread */
thread = thread->l.next;
cores[core].running = thread;
}
#endif /* HAVE_PRIORITY_SCHEDULING */
RTR_UNLOCK(core);
enable_irq();
break;
}
}
/* And finally give control to the next thread. */
load_context(&thread->context);
#ifdef RB_PROFILE
profile_thread_started(thread->id & THREAD_ID_SLOT_MASK);
#endif
}
/*---------------------------------------------------------------------------
* Sleeps a thread for at least a specified number of ticks with zero being
* a wait until the next tick.
*
* INTERNAL: Intended for use by kernel and not for programs.
*---------------------------------------------------------------------------
*/
void sleep_thread(int ticks)
{
struct thread_entry *current = cores[CURRENT_CORE].running;
LOCK_THREAD(current);
/* Set our timeout, remove from run list and join timeout list. */
current->tmo_tick = current_tick + ticks + 1;
block_thread_on_l(current, STATE_SLEEPING);
UNLOCK_THREAD(current);
}
/*---------------------------------------------------------------------------
* Indefinitely block a thread on a blocking queue for explicit wakeup.
*
* INTERNAL: Intended for use by kernel objects and not for programs.
*---------------------------------------------------------------------------
*/
void block_thread(struct thread_entry *current)
{
/* Set the state to blocked and take us off of the run queue until we
* are explicitly woken */
LOCK_THREAD(current);
/* Set the list for explicit wakeup */
block_thread_on_l(current, STATE_BLOCKED);
#ifdef HAVE_PRIORITY_SCHEDULING
if (current->blocker != NULL)
{
/* Object supports PIP */
current = blocker_inherit_priority(current);
}
#endif
UNLOCK_THREAD(current);
}
/*---------------------------------------------------------------------------
* Block a thread on a blocking queue for a specified time interval or until
* explicitly woken - whichever happens first.
*
* INTERNAL: Intended for use by kernel objects and not for programs.
*---------------------------------------------------------------------------
*/
void block_thread_w_tmo(struct thread_entry *current, int timeout)
{
/* Get the entry for the current running thread. */
LOCK_THREAD(current);
/* Set the state to blocked with the specified timeout */
current->tmo_tick = current_tick + timeout;
/* Set the list for explicit wakeup */
block_thread_on_l(current, STATE_BLOCKED_W_TMO);
#ifdef HAVE_PRIORITY_SCHEDULING
if (current->blocker != NULL)
{
/* Object supports PIP */
current = blocker_inherit_priority(current);
}
#endif
UNLOCK_THREAD(current);
}
/*---------------------------------------------------------------------------
* Explicitly wakeup a thread on a blocking queue. Only effects threads of
* STATE_BLOCKED and STATE_BLOCKED_W_TMO.
*
* This code should be considered a critical section by the caller meaning
* that the object's corelock should be held.
*
* INTERNAL: Intended for use by kernel objects and not for programs.
*---------------------------------------------------------------------------
*/
unsigned int wakeup_thread(struct thread_entry **list)
{
struct thread_entry *thread = *list;
unsigned int result = THREAD_NONE;
/* Check if there is a blocked thread at all. */
if (thread == NULL)
return result;
LOCK_THREAD(thread);
/* Determine thread's current state. */
switch (thread->state)
{
case STATE_BLOCKED:
case STATE_BLOCKED_W_TMO:
remove_from_list_l(list, thread);
result = THREAD_OK;
#ifdef HAVE_PRIORITY_SCHEDULING
struct thread_entry *current;
struct blocker *bl = thread->blocker;
if (bl == NULL)
{
/* No inheritance - just boost the thread by aging */
IF_NO_SKIP_YIELD( if (thread->skip_count != -1) )
thread->skip_count = thread->priority;
current = cores[CURRENT_CORE].running;
}
else
{
/* Call the specified unblocking PIP */
current = bl->wakeup_protocol(thread);
}
if (current != NULL &&
find_first_set_bit(cores[IF_COP_CORE(current->core)].rtr.mask)
< current->priority)
{
/* There is a thread ready to run of higher or same priority on
* the same core as the current one; recommend a task switch.
* Knowing if this is an interrupt call would be helpful here. */
result |= THREAD_SWITCH;
}
#endif /* HAVE_PRIORITY_SCHEDULING */
core_schedule_wakeup(thread);
break;
/* Nothing to do. State is not blocked. */
#if THREAD_EXTRA_CHECKS
default:
THREAD_PANICF("wakeup_thread->block invalid", thread);
case STATE_RUNNING:
case STATE_KILLED:
break;
#endif
}
UNLOCK_THREAD(thread);
return result;
}
/*---------------------------------------------------------------------------
* Wakeup an entire queue of threads - returns bitwise-or of return bitmask
* from each operation or THREAD_NONE of nothing was awakened. Object owning
* the queue must be locked first.
*
* INTERNAL: Intended for use by kernel objects and not for programs.
*---------------------------------------------------------------------------
*/
unsigned int thread_queue_wake(struct thread_entry **list)
{
unsigned result = THREAD_NONE;
for (;;)
{
unsigned int rc = wakeup_thread(list);
if (rc == THREAD_NONE)
break; /* No more threads */
result |= rc;
}
return result;
}
/*---------------------------------------------------------------------------
* Assign the thread slot a new ID. Version is 1-255.
*---------------------------------------------------------------------------
*/
static void new_thread_id(unsigned int slot_num,
struct thread_entry *thread)
{
unsigned int version =
(thread->id + (1u << THREAD_ID_VERSION_SHIFT))
& THREAD_ID_VERSION_MASK;
/* If wrapped to 0, make it 1 */
if (version == 0)
version = 1u << THREAD_ID_VERSION_SHIFT;
thread->id = version | (slot_num & THREAD_ID_SLOT_MASK);
}
/*---------------------------------------------------------------------------
* Find an empty thread slot or MAXTHREADS if none found. The slot returned
* will be locked on multicore.
*---------------------------------------------------------------------------
*/
static struct thread_entry * find_empty_thread_slot(void)
{
/* Any slot could be on an interrupt-accessible list */
IF_COP( int oldlevel = disable_irq_save(); )
struct thread_entry *thread = NULL;
int n;
for (n = 0; n < MAXTHREADS; n++)
{
/* Obtain current slot state - lock it on multicore */
struct thread_entry *t = &threads[n];
LOCK_THREAD(t);
if (t->state == STATE_KILLED IF_COP( && t->name != THREAD_DESTRUCT ))
{
/* Slot is empty - leave it locked and caller will unlock */
thread = t;
break;
}
/* Finished examining slot - no longer busy - unlock on multicore */
UNLOCK_THREAD(t);
}
IF_COP( restore_irq(oldlevel); ) /* Reenable interrups - this slot is
not accesible to them yet */
return thread;
}
/*---------------------------------------------------------------------------
* Return the thread_entry pointer for a thread_id. Return the current
* thread if the ID is 0 (alias for current).
*---------------------------------------------------------------------------
*/
struct thread_entry * thread_id_entry(unsigned int thread_id)
{
return (thread_id == THREAD_ID_CURRENT) ?
cores[CURRENT_CORE].running :
&threads[thread_id & THREAD_ID_SLOT_MASK];
}
/*---------------------------------------------------------------------------
* Place the current core in idle mode - woken up on interrupt or wake
* request from another core.
*---------------------------------------------------------------------------
*/
void core_idle(void)
{
IF_COP( const unsigned int core = CURRENT_CORE; )
disable_irq();
core_sleep(IF_COP(core));
}
/*---------------------------------------------------------------------------
* Create a thread. If using a dual core architecture, specify which core to
* start the thread on.
*
* Return ID if context area could be allocated, else NULL.
*---------------------------------------------------------------------------
*/
unsigned int create_thread(void (*function)(void),
void* stack, size_t stack_size,
unsigned flags, const char *name
IF_PRIO(, int priority)
IF_COP(, unsigned int core))
{
unsigned int i;
unsigned int stack_words;
uintptr_t stackptr, stackend;
struct thread_entry *thread;
unsigned state;
int oldlevel;
thread = find_empty_thread_slot();
if (thread == NULL)
{
return 0;
}
oldlevel = disable_irq_save();
/* Munge the stack to make it easy to spot stack overflows */
stackptr = ALIGN_UP((uintptr_t)stack, sizeof (uintptr_t));
stackend = ALIGN_DOWN((uintptr_t)stack + stack_size, sizeof (uintptr_t));
stack_size = stackend - stackptr;
stack_words = stack_size / sizeof (uintptr_t);
for (i = 0; i < stack_words; i++)
{
((uintptr_t *)stackptr)[i] = DEADBEEF;
}
/* Store interesting information */
thread->name = name;
thread->stack = (uintptr_t *)stackptr;
thread->stack_size = stack_size;
thread->queue = NULL;
#ifdef HAVE_WAKEUP_EXT_CB
thread->wakeup_ext_cb = NULL;
#endif
#ifdef HAVE_SCHEDULER_BOOSTCTRL
thread->cpu_boost = 0;
#endif
#ifdef HAVE_PRIORITY_SCHEDULING
memset(&thread->pdist, 0, sizeof(thread->pdist));
thread->blocker = NULL;
thread->base_priority = priority;
thread->priority = priority;
thread->skip_count = priority;
prio_add_entry(&thread->pdist, priority);
#endif
#ifdef HAVE_IO_PRIORITY
/* Default to high (foreground) priority */
thread->io_priority = IO_PRIORITY_IMMEDIATE;
#endif
#if NUM_CORES > 1
thread->core = core;
/* Writeback stack munging or anything else before starting */
if (core != CURRENT_CORE)
{
cpucache_flush();
}
#endif
/* Thread is not on any timeout list but be a bit paranoid */
thread->tmo.prev = NULL;
state = (flags & CREATE_THREAD_FROZEN) ?
STATE_FROZEN : STATE_RUNNING;
thread->context.sp = (typeof (thread->context.sp))stackend;
/* Load the thread's context structure with needed startup information */
THREAD_STARTUP_INIT(core, thread, function);
thread->state = state;
i = thread->id; /* Snapshot while locked */
if (state == STATE_RUNNING)
core_schedule_wakeup(thread);
UNLOCK_THREAD(thread);
restore_irq(oldlevel);
return i;
}
#ifdef HAVE_SCHEDULER_BOOSTCTRL
/*---------------------------------------------------------------------------
* Change the boost state of a thread boosting or unboosting the CPU
* as required.
*---------------------------------------------------------------------------
*/
static inline void boost_thread(struct thread_entry *thread, bool boost)
{
if ((thread->cpu_boost != 0) != boost)
{
thread->cpu_boost = boost;
cpu_boost(boost);
}
}
void trigger_cpu_boost(void)
{
struct thread_entry *current = cores[CURRENT_CORE].running;
boost_thread(current, true);
}
void cancel_cpu_boost(void)
{
struct thread_entry *current = cores[CURRENT_CORE].running;
boost_thread(current, false);
}
#endif /* HAVE_SCHEDULER_BOOSTCTRL */
/*---------------------------------------------------------------------------
* Block the current thread until another thread terminates. A thread may
* wait on itself to terminate which prevents it from running again and it
* will need to be killed externally.
* Parameter is the ID as returned from create_thread().
*---------------------------------------------------------------------------
*/
void thread_wait(unsigned int thread_id)
{
struct thread_entry *current = cores[CURRENT_CORE].running;
struct thread_entry *thread = thread_id_entry(thread_id);
/* Lock thread-as-waitable-object lock */
corelock_lock(&thread->waiter_cl);
/* Be sure it hasn't been killed yet */
if (thread_id == THREAD_ID_CURRENT ||
(thread->id == thread_id && thread->state != STATE_KILLED))
{
IF_COP( current->obj_cl = &thread->waiter_cl; )
current->bqp = &thread->queue;
disable_irq();
block_thread(current);
corelock_unlock(&thread->waiter_cl);
switch_thread();
return;
}
corelock_unlock(&thread->waiter_cl);
}
/*---------------------------------------------------------------------------
* Exit the current thread. The Right Way to Do Things (TM).
*---------------------------------------------------------------------------
*/
/* This is done to foil optimizations that may require the current stack,
* such as optimizing subexpressions that put variables on the stack that
* get used after switching stacks. */
#if NUM_CORES > 1
/* Called by ASM stub */
static void thread_final_exit_do(struct thread_entry *current)
#else
/* No special procedure is required before calling */
static inline void thread_final_exit(struct thread_entry *current)
#endif
{
/* At this point, this thread isn't using resources allocated for
* execution except the slot itself. */
/* Signal this thread */
thread_queue_wake(&current->queue);
corelock_unlock(&current->waiter_cl);
switch_thread();
/* This should never and must never be reached - if it is, the
* state is corrupted */
THREAD_PANICF("thread_exit->K:*R", current);
while (1);
}
void thread_exit(void)
{
register struct thread_entry * current = cores[CURRENT_CORE].running;
/* Cancel CPU boost if any */
cancel_cpu_boost();
disable_irq();
corelock_lock(&current->waiter_cl);
LOCK_THREAD(current);
#if defined (ALLOW_REMOVE_THREAD) && NUM_CORES > 1
if (current->name == THREAD_DESTRUCT)
{
/* Thread being killed - become a waiter */
unsigned int id = current->id;
UNLOCK_THREAD(current);
corelock_unlock(&current->waiter_cl);
thread_wait(id);
THREAD_PANICF("thread_exit->WK:*R", current);
}
#endif
#ifdef HAVE_PRIORITY_SCHEDULING
check_for_obj_waiters("thread_exit", current);
#endif
if (current->tmo.prev != NULL)
{
/* Cancel pending timeout list removal */
remove_from_list_tmo(current);
}
/* Switch tasks and never return */
block_thread_on_l(current, STATE_KILLED);
/* Slot must be unusable until thread is really gone */
UNLOCK_THREAD_AT_TASK_SWITCH(current);
/* Update ID for this slot */
new_thread_id(current->id, current);
current->name = NULL;
/* Do final cleanup and remove the thread */
thread_final_exit(current);
}
#ifdef ALLOW_REMOVE_THREAD
/*---------------------------------------------------------------------------
* Remove a thread from the scheduler. Not The Right Way to Do Things in
* normal programs.
*
* Parameter is the ID as returned from create_thread().
*
* Use with care on threads that are not under careful control as this may
* leave various objects in an undefined state.
*---------------------------------------------------------------------------
*/
void remove_thread(unsigned int thread_id)
{
#if NUM_CORES > 1
/* core is not constant here because of core switching */
unsigned int core = CURRENT_CORE;
unsigned int old_core = NUM_CORES;
struct corelock *ocl = NULL;
#else
const unsigned int core = CURRENT_CORE;
#endif
struct thread_entry *current = cores[core].running;
struct thread_entry *thread = thread_id_entry(thread_id);
unsigned state;
int oldlevel;
if (thread == current)
thread_exit(); /* Current thread - do normal exit */
oldlevel = disable_irq_save();
corelock_lock(&thread->waiter_cl);
LOCK_THREAD(thread);
state = thread->state;
if (thread->id != thread_id || state == STATE_KILLED)
goto thread_killed;
#if NUM_CORES > 1
if (thread->name == THREAD_DESTRUCT)
{
/* Thread being killed - become a waiter */
UNLOCK_THREAD(thread);
corelock_unlock(&thread->waiter_cl);
restore_irq(oldlevel);
thread_wait(thread_id);
return;
}
thread->name = THREAD_DESTRUCT; /* Slot can't be used for now */
#ifdef HAVE_PRIORITY_SCHEDULING
check_for_obj_waiters("remove_thread", thread);
#endif
if (thread->core != core)
{
/* Switch cores and safely extract the thread there */
/* Slot HAS to be unlocked or a deadlock could occur which means other
* threads have to be guided into becoming thread waiters if they
* attempt to remove it. */
unsigned int new_core = thread->core;
corelock_unlock(&thread->waiter_cl);
UNLOCK_THREAD(thread);
restore_irq(oldlevel);
old_core = switch_core(new_core);
oldlevel = disable_irq_save();
corelock_lock(&thread->waiter_cl);
LOCK_THREAD(thread);
state = thread->state;
core = new_core;
/* Perform the extraction and switch ourselves back to the original
processor */
}
#endif /* NUM_CORES > 1 */
if (thread->tmo.prev != NULL)
{
/* Clean thread off the timeout list if a timeout check hasn't
* run yet */
remove_from_list_tmo(thread);
}
#ifdef HAVE_SCHEDULER_BOOSTCTRL
/* Cancel CPU boost if any */
boost_thread(thread, false);
#endif
IF_COP( retry_state: )
switch (state)
{
case STATE_RUNNING:
RTR_LOCK(core);
/* Remove thread from ready to run tasks */
remove_from_list_l(&cores[core].running, thread);
rtr_subtract_entry(core, thread->priority);
RTR_UNLOCK(core);
break;
case STATE_BLOCKED:
case STATE_BLOCKED_W_TMO:
/* Remove thread from the queue it's blocked on - including its
* own if waiting there */
#if NUM_CORES > 1
if (&thread->waiter_cl != thread->obj_cl)
{
ocl = thread->obj_cl;
if (UNLIKELY(corelock_try_lock(ocl) == 0))
{
UNLOCK_THREAD(thread);
corelock_lock(ocl);
LOCK_THREAD(thread);
if (UNLIKELY(thread->state != state))
{
/* Something woke the thread */
state = thread->state;
corelock_unlock(ocl);
goto retry_state;
}
}
}
#endif
remove_from_list_l(thread->bqp, thread);
#ifdef HAVE_WAKEUP_EXT_CB
if (thread->wakeup_ext_cb != NULL)
thread->wakeup_ext_cb(thread);
#endif
#ifdef HAVE_PRIORITY_SCHEDULING
if (thread->blocker != NULL)
{
/* Remove thread's priority influence from its chain */
wakeup_priority_protocol_release(thread);
}
#endif
#if NUM_CORES > 1
if (ocl != NULL)
corelock_unlock(ocl);
#endif
break;
/* Otherwise thread is frozen and hasn't run yet */
}
new_thread_id(thread_id, thread);
thread->state = STATE_KILLED;
/* If thread was waiting on itself, it will have been removed above.
* The wrong order would result in waking the thread first and deadlocking
* since the slot is already locked. */
thread_queue_wake(&thread->queue);
thread->name = NULL;
thread_killed: /* Thread was already killed */
/* Removal complete - safe to unlock and reenable interrupts */
corelock_unlock(&thread->waiter_cl);
UNLOCK_THREAD(thread);
restore_irq(oldlevel);
#if NUM_CORES > 1
if (old_core < NUM_CORES)
{
/* Did a removal on another processor's thread - switch back to
native core */
switch_core(old_core);
}
#endif
}
#endif /* ALLOW_REMOVE_THREAD */
#ifdef HAVE_PRIORITY_SCHEDULING
/*---------------------------------------------------------------------------
* Sets the thread's relative base priority for the core it runs on. Any
* needed inheritance changes also may happen.
*---------------------------------------------------------------------------
*/
int thread_set_priority(unsigned int thread_id, int priority)
{
int old_base_priority = -1;
struct thread_entry *thread = thread_id_entry(thread_id);
/* A little safety measure */
if (priority < HIGHEST_PRIORITY || priority > LOWEST_PRIORITY)
return -1;
/* Thread could be on any list and therefore on an interrupt accessible
one - disable interrupts */
int oldlevel = disable_irq_save();
LOCK_THREAD(thread);
/* Make sure it's not killed */
if (thread_id == THREAD_ID_CURRENT ||
(thread->id == thread_id && thread->state != STATE_KILLED))
{
int old_priority = thread->priority;
old_base_priority = thread->base_priority;
thread->base_priority = priority;
prio_move_entry(&thread->pdist, old_base_priority, priority);
priority = find_first_set_bit(thread->pdist.mask);
if (old_priority == priority)
{
/* No priority change - do nothing */
}
else if (thread->state == STATE_RUNNING)
{
/* This thread is running - change location on the run
* queue. No transitive inheritance needed. */
set_running_thread_priority(thread, priority);
}
else
{
thread->priority = priority;
if (thread->blocker != NULL)
{
/* Bubble new priority down the chain */
struct blocker *bl = thread->blocker; /* Blocker struct */
struct thread_entry *bl_t = bl->thread; /* Blocking thread */
struct thread_entry * const tstart = thread; /* Initial thread */
const int highest = MIN(priority, old_priority); /* Higher of new or old */
for (;;)
{
struct thread_entry *next; /* Next thread to check */
int bl_pr; /* Highest blocked thread */
int queue_pr; /* New highest blocked thread */
#if NUM_CORES > 1
/* Owner can change but thread cannot be dislodged - thread
* may not be the first in the queue which allows other
* threads ahead in the list to be given ownership during the
* operation. If thread is next then the waker will have to
* wait for us and the owner of the object will remain fixed.
* If we successfully grab the owner -- which at some point
* is guaranteed -- then the queue remains fixed until we
* pass by. */
for (;;)
{
LOCK_THREAD(bl_t);
/* Double-check the owner - retry if it changed */
if (LIKELY(bl->thread == bl_t))
break;
UNLOCK_THREAD(bl_t);
bl_t = bl->thread;
}
#endif
bl_pr = bl->priority;
if (highest > bl_pr)
break; /* Object priority won't change */
/* This will include the thread being set */
queue_pr = find_highest_priority_in_list_l(*thread->bqp);
if (queue_pr == bl_pr)
break; /* Object priority not changing */
/* Update thread boost for this object */
bl->priority = queue_pr;
prio_move_entry(&bl_t->pdist, bl_pr, queue_pr);
bl_pr = find_first_set_bit(bl_t->pdist.mask);
if (bl_t->priority == bl_pr)
break; /* Blocking thread priority not changing */
if (bl_t->state == STATE_RUNNING)
{
/* Thread not blocked - we're done */
set_running_thread_priority(bl_t, bl_pr);
break;
}
bl_t->priority = bl_pr;
bl = bl_t->blocker; /* Blocking thread has a blocker? */
if (bl == NULL)
break; /* End of chain */
next = bl->thread;
if (UNLIKELY(next == tstart))
break; /* Full-circle */
UNLOCK_THREAD(thread);
thread = bl_t;
bl_t = next;
} /* for (;;) */
UNLOCK_THREAD(bl_t);
}
}
}
UNLOCK_THREAD(thread);
restore_irq(oldlevel);
return old_base_priority;
}
/*---------------------------------------------------------------------------
* Returns the current base priority for a thread.
*---------------------------------------------------------------------------
*/
int thread_get_priority(unsigned int thread_id)
{
struct thread_entry *thread = thread_id_entry(thread_id);
int base_priority = thread->base_priority;
/* Simply check without locking slot. It may or may not be valid by the
* time the function returns anyway. If all tests pass, it is the
* correct value for when it was valid. */
if (thread_id != THREAD_ID_CURRENT &&
(thread->id != thread_id || thread->state == STATE_KILLED))
base_priority = -1;
return base_priority;
}
#endif /* HAVE_PRIORITY_SCHEDULING */
#ifdef HAVE_IO_PRIORITY
int thread_get_io_priority(unsigned int thread_id)
{
struct thread_entry *thread = thread_id_entry(thread_id);
return thread->io_priority;
}
void thread_set_io_priority(unsigned int thread_id,int io_priority)
{
struct thread_entry *thread = thread_id_entry(thread_id);
thread->io_priority = io_priority;
}
#endif
/*---------------------------------------------------------------------------
* Starts a frozen thread - similar semantics to wakeup_thread except that
* the thread is on no scheduler or wakeup queue at all. It exists simply by
* virtue of the slot having a state of STATE_FROZEN.
*---------------------------------------------------------------------------
*/
void thread_thaw(unsigned int thread_id)
{
struct thread_entry *thread = thread_id_entry(thread_id);
int oldlevel = disable_irq_save();
LOCK_THREAD(thread);
/* If thread is the current one, it cannot be frozen, therefore
* there is no need to check that. */
if (thread->id == thread_id && thread->state == STATE_FROZEN)
core_schedule_wakeup(thread);
UNLOCK_THREAD(thread);
restore_irq(oldlevel);
}
/*---------------------------------------------------------------------------
* Return the ID of the currently executing thread.
*---------------------------------------------------------------------------
*/
unsigned int thread_get_current(void)
{
return cores[CURRENT_CORE].running->id;
}
#if NUM_CORES > 1
/*---------------------------------------------------------------------------
* Switch the processor that the currently executing thread runs on.
*---------------------------------------------------------------------------
*/
unsigned int switch_core(unsigned int new_core)
{
const unsigned int core = CURRENT_CORE;
struct thread_entry *current = cores[core].running;
if (core == new_core)
{
/* No change - just return same core */
return core;
}
int oldlevel = disable_irq_save();
LOCK_THREAD(current);
if (current->name == THREAD_DESTRUCT)
{
/* Thread being killed - deactivate and let process complete */
unsigned int id = current->id;
UNLOCK_THREAD(current);
restore_irq(oldlevel);
thread_wait(id);
/* Should never be reached */
THREAD_PANICF("switch_core->D:*R", current);
}
/* Get us off the running list for the current core */
RTR_LOCK(core);
remove_from_list_l(&cores[core].running, current);
rtr_subtract_entry(core, current->priority);
RTR_UNLOCK(core);
/* Stash return value (old core) in a safe place */
current->retval = core;
/* If a timeout hadn't yet been cleaned-up it must be removed now or
* the other core will likely attempt a removal from the wrong list! */
if (current->tmo.prev != NULL)
{
remove_from_list_tmo(current);
}
/* Change the core number for this thread slot */
current->core = new_core;
/* Do not use core_schedule_wakeup here since this will result in
* the thread starting to run on the other core before being finished on
* this one. Delay the list unlock to keep the other core stuck
* until this thread is ready. */
RTR_LOCK(new_core);
rtr_add_entry(new_core, current->priority);
add_to_list_l(&cores[new_core].running, current);
/* Make a callback into device-specific code, unlock the wakeup list so
* that execution may resume on the new core, unlock our slot and finally
* restore the interrupt level */
cores[core].blk_ops.flags = TBOP_SWITCH_CORE;
cores[core].blk_ops.cl_p = &cores[new_core].rtr_cl;
cores[core].block_task = current;
UNLOCK_THREAD(current);
/* Alert other core to activity */
core_wake(new_core);
/* Do the stack switching, cache_maintenence and switch_thread call -
requires native code */
switch_thread_core(core, current);
/* Finally return the old core to caller */
return current->retval;
}
#endif /* NUM_CORES > 1 */
/*---------------------------------------------------------------------------
* Initialize threading API. This assumes interrupts are not yet enabled. On
* multicore setups, no core is allowed to proceed until create_thread calls
* are safe to perform.
*---------------------------------------------------------------------------
*/
void init_threads(void)
{
const unsigned int core = CURRENT_CORE;
struct thread_entry *thread;
if (core == CPU)
{
/* Initialize core locks and IDs in all slots */
int n;
for (n = 0; n < MAXTHREADS; n++)
{
thread = &threads[n];
corelock_init(&thread->waiter_cl);
corelock_init(&thread->slot_cl);
thread->id = THREAD_ID_INIT(n);
}
}
/* CPU will initialize first and then sleep */
thread = find_empty_thread_slot();
if (thread == NULL)
{
/* WTF? There really must be a slot available at this stage.
* This can fail if, for example, .bss isn't zero'ed out by the loader
* or threads is in the wrong section. */
THREAD_PANICF("init_threads->no slot", NULL);
}
/* Initialize initially non-zero members of core */
cores[core].next_tmo_check = current_tick; /* Something not in the past */
/* Initialize initially non-zero members of slot */
UNLOCK_THREAD(thread); /* No sync worries yet */
thread->name = main_thread_name;
thread->state = STATE_RUNNING;
IF_COP( thread->core = core; )
#ifdef HAVE_PRIORITY_SCHEDULING
corelock_init(&cores[core].rtr_cl);
thread->base_priority = PRIORITY_USER_INTERFACE;
prio_add_entry(&thread->pdist, PRIORITY_USER_INTERFACE);
thread->priority = PRIORITY_USER_INTERFACE;
rtr_add_entry(core, PRIORITY_USER_INTERFACE);
#endif
add_to_list_l(&cores[core].running, thread);
if (core == CPU)
{
thread->stack = stackbegin;
thread->stack_size = (uintptr_t)stackend - (uintptr_t)stackbegin;
#if NUM_CORES > 1 /* This code path will not be run on single core targets */
/* Wait for other processors to finish their inits since create_thread
* isn't safe to call until the kernel inits are done. The first
* threads created in the system must of course be created by CPU.
* Another possible approach is to initialize all cores and slots
* for each core by CPU, let the remainder proceed in parallel and
* signal CPU when all are finished. */
core_thread_init(CPU);
}
else
{
/* Initial stack is the idle stack */
thread->stack = idle_stacks[core];
thread->stack_size = IDLE_STACK_SIZE;
/* After last processor completes, it should signal all others to
* proceed or may signal the next and call thread_exit(). The last one
* to finish will signal CPU. */
core_thread_init(core);
/* Other cores do not have a main thread - go idle inside switch_thread
* until a thread can run on the core. */
thread_exit();
#endif /* NUM_CORES */
}
}
/* Shared stack scan helper for thread_stack_usage and idle_stack_usage */
#if NUM_CORES == 1
static inline int stack_usage(uintptr_t *stackptr, size_t stack_size)
#else
static int stack_usage(uintptr_t *stackptr, size_t stack_size)
#endif
{
unsigned int stack_words = stack_size / sizeof (uintptr_t);
unsigned int i;
int usage = 0;
for (i = 0; i < stack_words; i++)
{
if (stackptr[i] != DEADBEEF)
{
usage = ((stack_words - i) * 100) / stack_words;
break;
}
}
return usage;
}
/*---------------------------------------------------------------------------
* Returns the maximum percentage of stack a thread ever used while running.
* NOTE: Some large buffer allocations that don't use enough the buffer to
* overwrite stackptr[0] will not be seen.
*---------------------------------------------------------------------------
*/
int thread_stack_usage(const struct thread_entry *thread)
{
if (LIKELY(thread->stack_size > 0))
return stack_usage(thread->stack, thread->stack_size);
return 0;
}
#if NUM_CORES > 1
/*---------------------------------------------------------------------------
* Returns the maximum percentage of the core's idle stack ever used during
* runtime.
*---------------------------------------------------------------------------
*/
int idle_stack_usage(unsigned int core)
{
return stack_usage(idle_stacks[core], IDLE_STACK_SIZE);
}
#endif
/*---------------------------------------------------------------------------
* Fills in the buffer with the specified thread's name. If the name is NULL,
* empty, or the thread is in destruct state a formatted ID is written
* instead.
*---------------------------------------------------------------------------
*/
void thread_get_name(char *buffer, int size,
struct thread_entry *thread)
{
if (size <= 0)
return;
*buffer = '\0';
if (thread)
{
/* Display thread name if one or ID if none */
const char *name = thread->name;
const char *fmt = "%s";
if (name == NULL IF_COP(|| name == THREAD_DESTRUCT) || *name == '\0')
{
name = (const char *)thread;
fmt = "%08lX";
}
snprintf(buffer, size, fmt, name);
}
}
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