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Fix semaphore deadlocks

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- Fixed unbalanced semaphores (which may cause deadlock)
- Do semaphore-up before blocking calls for communication with the server
- Don't discard semaphores on the client side
- Open slave PCMs always in non-blocking mode to avoid blocking by semaphore
  with the secondary open
This commit is contained in:
Takashi Iwai 2005-05-23 08:56:48 +00:00
parent ddd9c29a0d
commit a3ae02d884
4 changed files with 88 additions and 102 deletions
Download patch file Download diff file Expand all files Collapse all files

64
src/pcm/pcm_dshare.c
View file

@ -459,12 +459,8 @@ static int snd_pcm_dshare_close(snd_pcm_t *pcm)
snd_pcm_direct_server_discard(dshare);
if (dshare->client)
snd_pcm_direct_client_discard(dshare);
if (snd_pcm_direct_shm_discard(dshare) > 0) {
if (snd_pcm_direct_semaphore_discard(dshare) < 0)
snd_pcm_direct_semaphore_up(dshare, DIRECT_IPC_SEM_CLIENT);
} else {
snd_pcm_direct_semaphore_up(dshare, DIRECT_IPC_SEM_CLIENT);
}
snd_pcm_direct_shm_discard(dshare);
snd_pcm_direct_semaphore_up(dshare, DIRECT_IPC_SEM_CLIENT);
if (dshare->bindings)
free(dshare->bindings);
pcm->private_data = NULL;
@ -614,17 +610,17 @@ int snd_pcm_dshare_open(snd_pcm_t **pcmp, const char *name,
dshare = calloc(1, sizeof(snd_pcm_direct_t));
if (!dshare) {
ret = -ENOMEM;
goto _err;
goto _err_nosem;
}
ret = snd_pcm_direct_parse_bindings(dshare, bindings);
if (ret < 0)
goto _err;
goto _err_nosem;
if (!dshare->bindings) {
SNDERR("dshare: specify bindings!!!");
ret = -EINVAL;
goto _err;
goto _err_nosem;
}
dshare->ipc_key = ipc_key;
@ -634,20 +630,20 @@ int snd_pcm_dshare_open(snd_pcm_t **pcmp, const char *name,
ret = snd_pcm_new(&pcm, dshare->type = SND_PCM_TYPE_DSHARE, name, stream, mode);
if (ret < 0)
goto _err;
goto _err_nosem;
while (1) {
ret = snd_pcm_direct_semaphore_create_or_connect(dshare);
if (ret < 0) {
SNDERR("unable to create IPC semaphore");
goto _err;
goto _err_nosem;
}
ret = snd_pcm_direct_semaphore_down(dshare, DIRECT_IPC_SEM_CLIENT);
if (ret < 0) {
snd_pcm_direct_semaphore_discard(dshare);
if (--fail_sem_loop <= 0)
goto _err;
goto _err_nosem;
continue;
}
break;
@ -667,7 +663,7 @@ int snd_pcm_dshare_open(snd_pcm_t **pcmp, const char *name,
dshare->sync_ptr = snd_pcm_dshare_sync_ptr;
if (first_instance) {
ret = snd_pcm_open_slave(&spcm, root, sconf, stream, mode);
ret = snd_pcm_open_slave(&spcm, root, sconf, stream, mode | SND_PCM_NONBLOCK);
if (ret < 0) {
SNDERR("unable to open slave");
goto _err;
@ -694,12 +690,15 @@ int snd_pcm_dshare_open(snd_pcm_t **pcmp, const char *name,
dshare->shmptr->type = spcm->type;
} else {
/* up semaphore to avoid deadlock */
snd_pcm_direct_semaphore_up(dshare, DIRECT_IPC_SEM_CLIENT);
ret = snd_pcm_direct_client_connect(dshare);
if (ret < 0) {
SNDERR("unable to connect client");
return ret;
goto _err_nosem;
}
snd_pcm_direct_semaphore_down(dshare, DIRECT_IPC_SEM_CLIENT);
ret = snd_pcm_hw_open_fd(&spcm, "dshare_client", dshare->hw_fd, 0, 0);
if (ret < 0) {
SNDERR("unable to open hardware");
@ -751,27 +750,24 @@ int snd_pcm_dshare_open(snd_pcm_t **pcmp, const char *name,
return 0;
_err:
if (dshare->shmptr)
dshare->shmptr->u.dshare.chn_mask &= ~dshare->u.dshare.chn_mask;
if (dshare->timer)
snd_timer_close(dshare->timer);
if (dshare->server)
snd_pcm_direct_server_discard(dshare);
if (dshare->client)
snd_pcm_direct_client_discard(dshare);
if (spcm)
snd_pcm_close(spcm);
if (dshare->shmid >= 0)
snd_pcm_direct_shm_discard(dshare);
if (snd_pcm_direct_semaphore_discard(dshare) < 0)
snd_pcm_direct_semaphore_up(dshare, DIRECT_IPC_SEM_CLIENT);
_err_nosem:
if (dshare) {
if (dshare->shmptr)
dshare->shmptr->u.dshare.chn_mask &= ~dshare->u.dshare.chn_mask;
if (dshare->timer)
snd_timer_close(dshare->timer);
if (dshare->server)
snd_pcm_direct_server_discard(dshare);
if (dshare->client)
snd_pcm_direct_client_discard(dshare);
if (spcm)
snd_pcm_close(spcm);
if (dshare->shmid >= 0) {
if (snd_pcm_direct_shm_discard(dshare) > 0) {
if (dshare->semid >= 0) {
if (snd_pcm_direct_semaphore_discard(dshare) < 0)
snd_pcm_direct_semaphore_up(dshare, DIRECT_IPC_SEM_CLIENT);
}
}
}
if (dshare->bindings)
free(dshare->bindings);
if (dshare->bindings)
free(dshare->bindings);
free(dshare);
}
if (pcm)