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rockbox/firmware/thread.c
Boris Gjenero 8906b3e659 Convert remaining __attribute__((noreturn)) to NORETURN_ATTR. 
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@31189 a1c6a512-1295-4272-9138-f99709370657
2011-12-09 16:13:03 +00:00

2390 lines
75 KiB
C
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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
#include "gcc_extensions.h"
/****************************************************************************
* 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_ATTR USED_ATTR;
#else
static inline void thread_final_exit(struct thread_entry *current)
__attribute__((always_inline)) NORETURN_ATTR;
#endif
void switch_thread(void)
__attribute__((noinline));
/****************************************************************************
* Processor/OS-specific section - include necessary core support
*/
#if defined(HAVE_WIN32_FIBER_THREADS)
#include "thread-win32.c"
#elif defined(HAVE_SIGALTSTACK_THREADS)
#include "thread-unix.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)
{
#ifdef HAVE_CORELOCK_OBJECT
/* 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
#ifdef CPU_COLDFIRE
_profile_thread_stopped(thread->id & THREAD_ID_SLOT_MASK);
#else
profile_thread_stopped(thread->id & THREAD_ID_SLOT_MASK);
#endif
#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 (unsigned int)-1 (alias for current).
*---------------------------------------------------------------------------
*/
struct thread_entry * thread_id_entry(unsigned int thread_id)
{
return &threads[thread_id & THREAD_ID_SLOT_MASK];
}
/*---------------------------------------------------------------------------
* Return the thread id of the calling thread
* --------------------------------------------------------------------------
*/
unsigned int thread_self(void)
{
return cores[CURRENT_CORE].running->id;
}
/*---------------------------------------------------------------------------
* Return the thread entry of the calling thread.
*
* INTERNAL: Intended for use by kernel and not for programs.
*---------------------------------------------------------------------------
*/
struct thread_entry* thread_self_entry(void)
{
return cores[CURRENT_CORE].running;
}
/*---------------------------------------------------------------------------
* 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 && 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)
{
#ifdef HAVE_CORELOCK_OBJECT
/* 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 && 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 || 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);
}
#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 */
}
#ifdef INIT_MAIN_THREAD
init_main_thread(&thread->context);
#endif
}
/* 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 *)(uintptr_t)thread->id;
fmt = "%04lX";
}
snprintf(buffer, size, fmt, name);
}
}
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