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quake: fix race condition

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COM_LoadStackFile was not thread-safe since it relied on a global variable
to pass the loadbuf parameter to COM_LoadFile. This was causing mysterious
crashes when model loading and audio mixing were happening simultaneously.

Change-Id: I505c5ef0ed49d0c4aa4b11cfed05647c75b5b40d
This commit is contained in:
Franklin Wei 2019-07-29 20:59:11 -04:00
parent 0b23348610
commit caee6c578d
2 changed files with 37 additions and 7 deletions
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27
apps/plugins/sdl/progs/quake/common.c
View file

@ -1614,6 +1614,9 @@ byte *COM_LoadFile (char *path, int usehunk)
if (h == -1)
return NULL;
if(len < 1)
rb->splashf(HZ, "suspicious length %d", len);
check_ptr = &h;
//printf("handle %d", h);
@ -1635,10 +1638,16 @@ byte *COM_LoadFile (char *path, int usehunk)
else if (usehunk == 4)
{
if (len+1 > loadsize)
{
LOGF("LoadFile: allocating hunk b/c stackbuf too small (filelen=%d)\n", len);
buf = Hunk_TempAlloc (len+1);
}
else
{
LOGF("filelen=%d, using stack buf\n", len);
buf = loadbuf;
}
}
else
Sys_Error ("COM_LoadFile: bad usehunk");
@ -1671,15 +1680,33 @@ void COM_LoadCacheFile (char *path, struct cache_user_s *cu)
COM_LoadFile (path, 3);
}
/*
* This function was NOT originally thread-safe, leading to a race
* condition between the Mod_LoadModel and S_LoadSound (which run in
* different threads). Fixed with mutex lock. - FW 7/29/19
*/
// uses temp hunk if larger than bufsize
byte *COM_LoadStackFile (char *path, void *buffer, int bufsize)
{
static struct mutex m;
static int init = 0;
if(!init)
{
rb->mutex_init(&m);
init = 1;
}
rb->mutex_lock(&m);
byte *buf;
loadbuf = (byte *)buffer;
loadsize = bufsize;
buf = COM_LoadFile (path, 4);
rb->mutex_unlock(&m);
return buf;
}

3
apps/plugins/sdl/progs/quake/model.c
View file

@ -1472,8 +1472,11 @@ void Mod_LoadAliasModel (model_t *mod, void *buffer)
version = LittleLongUnaligned (pinmodel->version);
if (version != ALIAS_VERSION)
{
rb->splashf(HZ*2, "Likely race condition! S_LoadSound and this use the same allocator!");
Sys_Error ("%s has wrong version number (%i should be %i)",
mod->name, version, ALIAS_VERSION);
}
//
// allocate space for a working header, plus all the data except the frames,