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ALSA: Fix a deadlock when stopping devices.

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Public issue https://github.com/mackron/miniaudio/issues/291
This commit is contained in:
David Reid
2021-04-26 11:54:52 +10:00
parent 95bd7fb53b
commit 403e9f7a74
1 changed files with 183 additions and 0 deletions
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miniaudio.h
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@@ -3726,6 +3726,7 @@ struct ma_context
ma_proc snd_pcm_start;
ma_proc snd_pcm_drop;
ma_proc snd_pcm_drain;
ma_proc snd_pcm_reset;
ma_proc snd_device_name_hint;
ma_proc snd_device_name_get_hint;
ma_proc snd_card_get_index;
@@ -3738,9 +3739,13 @@ struct ma_context
ma_proc snd_pcm_avail;
ma_proc snd_pcm_avail_update;
ma_proc snd_pcm_wait;
ma_proc snd_pcm_nonblock;
ma_proc snd_pcm_info;
ma_proc snd_pcm_info_sizeof;
ma_proc snd_pcm_info_get_name;
ma_proc snd_pcm_poll_descriptors;
ma_proc snd_pcm_poll_descriptors_count;
ma_proc snd_pcm_poll_descriptors_revents;
ma_proc snd_config_update_free_global;
ma_mutex internalDeviceEnumLock;
@@ -4149,6 +4154,12 @@ struct ma_device
{
/*snd_pcm_t**/ ma_ptr pPCMPlayback;
/*snd_pcm_t**/ ma_ptr pPCMCapture;
/*struct pollfd**/ void* pPollDescriptorsPlayback;
/*struct pollfd**/ void* pPollDescriptorsCapture;
int pollDescriptorCountPlayback;
int pollDescriptorCountCapture;
int wakeupfdPlayback; /* eventfd for waking up from poll() when the playback device is stopped. */
int wakeupfdCapture; /* eventfd for waking up from poll() when the capture device is stopped. */
ma_bool8 isUsingMMapPlayback;
ma_bool8 isUsingMMapCapture;
} alsa;
@@ -19113,6 +19124,9 @@ ALSA Backend
******************************************************************************/
#ifdef MA_HAS_ALSA
#include <poll.h> /* poll(), struct pollfd */
#include <sys/eventfd.h> /* eventfd() */
#ifdef MA_NO_RUNTIME_LINKING
/* asoundlib.h marks some functions with "inline" which isn't always supported. Need to emulate it. */
@@ -19371,6 +19385,7 @@ typedef int (* ma_snd_pcm_prepare_proc) (
typedef int (* ma_snd_pcm_start_proc) (ma_snd_pcm_t *pcm);
typedef int (* ma_snd_pcm_drop_proc) (ma_snd_pcm_t *pcm);
typedef int (* ma_snd_pcm_drain_proc) (ma_snd_pcm_t *pcm);
typedef int (* ma_snd_pcm_reset_proc) (ma_snd_pcm_t *pcm);
typedef int (* ma_snd_device_name_hint_proc) (int card, const char *iface, void ***hints);
typedef char * (* ma_snd_device_name_get_hint_proc) (const void *hint, const char *id);
typedef int (* ma_snd_card_get_index_proc) (const char *name);
@@ -19383,9 +19398,13 @@ typedef ma_snd_pcm_sframes_t (* ma_snd_pcm_writei_proc) (
typedef ma_snd_pcm_sframes_t (* ma_snd_pcm_avail_proc) (ma_snd_pcm_t *pcm);
typedef ma_snd_pcm_sframes_t (* ma_snd_pcm_avail_update_proc) (ma_snd_pcm_t *pcm);
typedef int (* ma_snd_pcm_wait_proc) (ma_snd_pcm_t *pcm, int timeout);
typedef int (* ma_snd_pcm_nonblock_proc) (ma_snd_pcm_t *pcm, int nonblock);
typedef int (* ma_snd_pcm_info_proc) (ma_snd_pcm_t *pcm, ma_snd_pcm_info_t* info);
typedef size_t (* ma_snd_pcm_info_sizeof_proc) (void);
typedef const char* (* ma_snd_pcm_info_get_name_proc) (const ma_snd_pcm_info_t* info);
typedef int (* ma_snd_pcm_poll_descriptors_proc) (ma_snd_pcm_t *pcm, struct pollfd *pfds, unsigned int space);
typedef int (* ma_snd_pcm_poll_descriptors_count_proc) (ma_snd_pcm_t *pcm);
typedef int (* ma_snd_pcm_poll_descriptors_revents_proc) (ma_snd_pcm_t *pcm, struct pollfd *pfds, unsigned int nfds, unsigned short *revents);
typedef int (* ma_snd_config_update_free_global_proc) (void);
/* This array specifies each of the common devices that can be used for both playback and capture. */
@@ -20195,10 +20214,14 @@ static ma_result ma_device_uninit__alsa(ma_device* pDevice)
if ((ma_snd_pcm_t*)pDevice->alsa.pPCMCapture) {
((ma_snd_pcm_close_proc)pDevice->pContext->alsa.snd_pcm_close)((ma_snd_pcm_t*)pDevice->alsa.pPCMCapture);
close(pDevice->alsa.wakeupfdCapture);
ma_free(pDevice->alsa.pPollDescriptorsCapture, &pDevice->pContext->allocationCallbacks);
}
if ((ma_snd_pcm_t*)pDevice->alsa.pPCMPlayback) {
((ma_snd_pcm_close_proc)pDevice->pContext->alsa.snd_pcm_close)((ma_snd_pcm_t*)pDevice->alsa.pPCMPlayback);
close(pDevice->alsa.wakeupfdPlayback);
ma_free(pDevice->alsa.pPollDescriptorsPlayback, &pDevice->pContext->allocationCallbacks);
}
return MA_SUCCESS;
@@ -20221,6 +20244,9 @@ static ma_result ma_device_init_by_type__alsa(ma_device* pDevice, const ma_devic
ma_snd_pcm_hw_params_t* pHWParams;
ma_snd_pcm_sw_params_t* pSWParams;
ma_snd_pcm_uframes_t bufferBoundary;
int pollDescriptorCount;
struct pollfd* pPollDescriptors;
int wakeupfd;
MA_ASSERT(pConfig != NULL);
MA_ASSERT(deviceType != ma_device_type_duplex); /* This function should only be called for playback _or_ capture, never duplex. */
@@ -20533,9 +20559,62 @@ static ma_result ma_device_init_by_type__alsa(ma_device* pDevice, const ma_devic
}
/*
We need to retrieve the poll descriptors so we can use poll() to wait for data to become
available for reading or writing. There's no well defined maximum for this so we're just going
to allocate this on the heap.
*/
pollDescriptorCount = ((ma_snd_pcm_poll_descriptors_count_proc)pDevice->pContext->alsa.snd_pcm_poll_descriptors_count)(pPCM);
if (pollDescriptorCount <= 0) {
((ma_snd_pcm_close_proc)pDevice->pContext->alsa.snd_pcm_close)(pPCM);
return ma_post_error(pDevice, MA_LOG_LEVEL_ERROR, "[ALSA] Failed to retrieve poll descriptors count.", MA_ERROR);
}
pPollDescriptors = (struct pollfd*)ma_malloc(sizeof(*pPollDescriptors) * (pollDescriptorCount + 1), &pDevice->pContext->allocationCallbacks/*, MA_ALLOCATION_TYPE_GENERAL*/); /* +1 because we want room for the wakeup descriptor. */
if (pPollDescriptors == NULL) {
((ma_snd_pcm_close_proc)pDevice->pContext->alsa.snd_pcm_close)(pPCM);
return ma_post_error(pDevice, MA_LOG_LEVEL_ERROR, "[ALSA] Failed to allocate memory for poll descriptors.", MA_OUT_OF_MEMORY);
}
/*
We need an eventfd to wakeup from poll() and avoid a deadlock in situations where the driver
never returns from writei() and readi(). This has been observed with the "pulse" device.
*/
wakeupfd = eventfd(0, 0);
if (wakeupfd < 0) {
ma_free(pPollDescriptors, &pDevice->pContext->allocationCallbacks);
((ma_snd_pcm_close_proc)pDevice->pContext->alsa.snd_pcm_close)(pPCM);
return ma_post_error(pDevice, MA_LOG_LEVEL_ERROR, "[ALSA] Failed to create eventfd for poll wakeup.", ma_result_from_errno(errno));
}
/* We'll place the wakeup fd at the start of the buffer. */
pPollDescriptors[0].fd = wakeupfd;
pPollDescriptors[0].events = POLLIN; /* We only care about waiting to read from the wakeup file descriptor. */
pPollDescriptors[0].revents = 0;
/* We can now extract the PCM poll descriptors which we place after the wakeup descriptor. */
pollDescriptorCount = ((ma_snd_pcm_poll_descriptors_proc)pDevice->pContext->alsa.snd_pcm_poll_descriptors)(pPCM, pPollDescriptors + 1, pollDescriptorCount); /* +1 because we want to place these descriptors after the wakeup descriptor. */
if (pollDescriptorCount <= 0) {
((ma_snd_pcm_close_proc)pDevice->pContext->alsa.snd_pcm_close)(pPCM);
return ma_post_error(pDevice, MA_LOG_LEVEL_ERROR, "[ALSA] Failed to retrieve poll descriptors.", MA_ERROR);
}
if (deviceType == ma_device_type_capture) {
pDevice->alsa.pollDescriptorCountCapture = pollDescriptorCount;
pDevice->alsa.pPollDescriptorsCapture = pPollDescriptors;
pDevice->alsa.wakeupfdCapture = wakeupfd;
} else {
pDevice->alsa.pollDescriptorCountPlayback = pollDescriptorCount;
pDevice->alsa.pPollDescriptorsPlayback = pPollDescriptors;
pDevice->alsa.wakeupfdPlayback = wakeupfd;
}
/* We're done. Prepare the device. */
resultALSA = ((ma_snd_pcm_prepare_proc)pDevice->pContext->alsa.snd_pcm_prepare)(pPCM);
if (resultALSA < 0) {
close(wakeupfd);
ma_free(pPollDescriptors, &pDevice->pContext->allocationCallbacks);
((ma_snd_pcm_close_proc)pDevice->pContext->alsa.snd_pcm_close)(pPCM);
return ma_post_error(pDevice, MA_LOG_LEVEL_ERROR, "[ALSA] Failed to prepare device.", ma_result_from_errno(-resultALSA));
}
@@ -20633,6 +20712,59 @@ static ma_result ma_device_stop__alsa(ma_device* pDevice)
return MA_SUCCESS;
}
static ma_result ma_device_wait__alsa(ma_device* pDevice, ma_snd_pcm_t* pPCM, struct pollfd* pPollDescriptors, int pollDescriptorCount, short requiredEvent)
{
for (;;) {
unsigned short revents;
int resultALSA;
int resultPoll = poll(pPollDescriptors, pollDescriptorCount, -1);
if (resultPoll < 0) {
return ma_post_error(pDevice, MA_LOG_LEVEL_ERROR, "[ALSA] poll() failed.", ma_result_from_errno(errno));
}
/*
Before checking the ALSA poll descriptor flag we need to check if the wakeup descriptor
has had it's POLLIN flag set. If so, we need to actually read the data and then exit
function. The wakeup descriptor will be the first item in the descriptors buffer.
*/
if ((pPollDescriptors[0].revents & POLLIN) != 0) {
ma_uint64 t;
read(pPollDescriptors[0].fd, &t, sizeof(t)); /* <-- Important that we read here so that the next write() does not block. */
return MA_DEVICE_NOT_STARTED;
}
/*
Getting here means that some data should be able to be read. We need to use ALSA to
translate the revents flags for us.
*/
resultALSA = ((ma_snd_pcm_poll_descriptors_revents_proc)pDevice->pContext->alsa.snd_pcm_poll_descriptors_revents)(pPCM, pPollDescriptors + 1, pollDescriptorCount - 1, &revents); /* +1, -1 to ignore the wakeup descriptor. */
if (resultALSA < 0) {
return ma_post_error(pDevice, MA_LOG_LEVEL_ERROR, "[ALSA] snd_pcm_poll_descriptors_revents() failed.", ma_result_from_errno(-resultALSA));
}
if ((revents & POLLERR) != 0) {
return ma_post_error(pDevice, MA_LOG_LEVEL_ERROR, "[ALSA] POLLERR detected.", ma_result_from_errno(errno));
return MA_ERROR;
}
if ((revents & requiredEvent) == requiredEvent) {
break; /* We're done. Data available for reading or writing. */
}
}
return MA_SUCCESS;
}
static ma_result ma_device_wait_read__alsa(ma_device* pDevice)
{
return ma_device_wait__alsa(pDevice, pDevice->alsa.pPCMCapture, (struct pollfd*)pDevice->alsa.pPollDescriptorsCapture, pDevice->alsa.pollDescriptorCountCapture + 1, POLLIN); /* +1 to account for the wakeup descriptor. */
}
static ma_result ma_device_wait_write__alsa(ma_device* pDevice)
{
return ma_device_wait__alsa(pDevice, pDevice->alsa.pPCMPlayback, (struct pollfd*)pDevice->alsa.pPollDescriptorsPlayback, pDevice->alsa.pollDescriptorCountPlayback + 1, POLLOUT); /* +1 to account for the wakeup descriptor. */
}
static ma_result ma_device_read__alsa(ma_device* pDevice, void* pFramesOut, ma_uint32 frameCount, ma_uint32* pFramesRead)
{
ma_snd_pcm_sframes_t resultALSA;
@@ -20645,6 +20777,15 @@ static ma_result ma_device_read__alsa(ma_device* pDevice, void* pFramesOut, ma_u
}
for (;;) {
ma_result result;
/* The first thing to do is wait for data to become available for reading. This will return an error code if the device has been stopped. */
result = ma_device_wait_read__alsa(pDevice);
if (result != MA_SUCCESS) {
return result;
}
/* Getting here means we should have data available. */
resultALSA = ((ma_snd_pcm_readi_proc)pDevice->pContext->alsa.snd_pcm_readi)((ma_snd_pcm_t*)pDevice->alsa.pPCMCapture, pFramesOut, frameCount);
if (resultALSA >= 0) {
break; /* Success. */
@@ -20695,6 +20836,14 @@ static ma_result ma_device_write__alsa(ma_device* pDevice, const void* pFrames,
}
for (;;) {
ma_result result;
/* The first thing to do is wait for space to become available for writing. This will return an error code if the device has been stopped. */
result = ma_device_wait_write__alsa(pDevice);
if (result != MA_SUCCESS) {
return result;
}
resultALSA = ((ma_snd_pcm_writei_proc)pDevice->pContext->alsa.snd_pcm_writei)((ma_snd_pcm_t*)pDevice->alsa.pPCMPlayback, pFrames, frameCount);
if (resultALSA >= 0) {
break; /* Success. */
@@ -20740,6 +20889,23 @@ static ma_result ma_device_write__alsa(ma_device* pDevice, const void* pFrames,
return MA_SUCCESS;
}
static ma_result ma_device_data_loop_wakeup__alsa(ma_device* pDevice)
{
ma_uint64 t = 1;
MA_ASSERT(pDevice != NULL);
/* Write to an eventfd to trigger a wakeup from poll() and abort any reading or writing. */
if (pDevice->alsa.pPollDescriptorsCapture != NULL) {
write(pDevice->alsa.wakeupfdCapture, &t, sizeof(t));
}
if (pDevice->alsa.pPollDescriptorsPlayback != NULL) {
write(pDevice->alsa.wakeupfdPlayback, &t, sizeof(t));
}
return MA_SUCCESS;
}
static ma_result ma_context_uninit__alsa(ma_context* pContext)
{
MA_ASSERT(pContext != NULL);
@@ -20825,6 +20991,7 @@ static ma_result ma_context_init__alsa(ma_context* pContext, const ma_context_co
pContext->alsa.snd_pcm_start = (ma_proc)ma_dlsym(pContext, pContext->alsa.asoundSO, "snd_pcm_start");
pContext->alsa.snd_pcm_drop = (ma_proc)ma_dlsym(pContext, pContext->alsa.asoundSO, "snd_pcm_drop");
pContext->alsa.snd_pcm_drain = (ma_proc)ma_dlsym(pContext, pContext->alsa.asoundSO, "snd_pcm_drain");
pContext->alsa.snd_pcm_reset = (ma_proc)ma_dlsym(pContext, pContext->alsa.asoundSO, "snd_pcm_reset");
pContext->alsa.snd_device_name_hint = (ma_proc)ma_dlsym(pContext, pContext->alsa.asoundSO, "snd_device_name_hint");
pContext->alsa.snd_device_name_get_hint = (ma_proc)ma_dlsym(pContext, pContext->alsa.asoundSO, "snd_device_name_get_hint");
pContext->alsa.snd_card_get_index = (ma_proc)ma_dlsym(pContext, pContext->alsa.asoundSO, "snd_card_get_index");
@@ -20837,9 +21004,13 @@ static ma_result ma_context_init__alsa(ma_context* pContext, const ma_context_co
pContext->alsa.snd_pcm_avail = (ma_proc)ma_dlsym(pContext, pContext->alsa.asoundSO, "snd_pcm_avail");
pContext->alsa.snd_pcm_avail_update = (ma_proc)ma_dlsym(pContext, pContext->alsa.asoundSO, "snd_pcm_avail_update");
pContext->alsa.snd_pcm_wait = (ma_proc)ma_dlsym(pContext, pContext->alsa.asoundSO, "snd_pcm_wait");
pContext->alsa.snd_pcm_nonblock = (ma_proc)ma_dlsym(pContext, pContext->alsa.asoundSO, "snd_pcm_nonblock");
pContext->alsa.snd_pcm_info = (ma_proc)ma_dlsym(pContext, pContext->alsa.asoundSO, "snd_pcm_info");
pContext->alsa.snd_pcm_info_sizeof = (ma_proc)ma_dlsym(pContext, pContext->alsa.asoundSO, "snd_pcm_info_sizeof");
pContext->alsa.snd_pcm_info_get_name = (ma_proc)ma_dlsym(pContext, pContext->alsa.asoundSO, "snd_pcm_info_get_name");
pContext->alsa.snd_pcm_poll_descriptors = (ma_proc)ma_dlsym(pContext, pContext->alsa.asoundSO, "snd_pcm_poll_descriptors");
pContext->alsa.snd_pcm_poll_descriptors_count = (ma_proc)ma_dlsym(pContext, pContext->alsa.asoundSO, "snd_pcm_poll_descriptors_count");
pContext->alsa.snd_pcm_poll_descriptors_revents = (ma_proc)ma_dlsym(pContext, pContext->alsa.asoundSO, "snd_pcm_poll_descriptors_revents");
pContext->alsa.snd_config_update_free_global = (ma_proc)ma_dlsym(pContext, pContext->alsa.asoundSO, "snd_config_update_free_global");
#else
/* The system below is just for type safety. */
@@ -20888,6 +21059,7 @@ static ma_result ma_context_init__alsa(ma_context* pContext, const ma_context_co
ma_snd_pcm_start_proc _snd_pcm_start = snd_pcm_start;
ma_snd_pcm_drop_proc _snd_pcm_drop = snd_pcm_drop;
ma_snd_pcm_drain_proc _snd_pcm_drain = snd_pcm_drain;
ma_snd_pcm_reset_proc _snd_pcm_reset = snd_pcm_reset;
ma_snd_device_name_hint_proc _snd_device_name_hint = snd_device_name_hint;
ma_snd_device_name_get_hint_proc _snd_device_name_get_hint = snd_device_name_get_hint;
ma_snd_card_get_index_proc _snd_card_get_index = snd_card_get_index;
@@ -20900,9 +21072,13 @@ static ma_result ma_context_init__alsa(ma_context* pContext, const ma_context_co
ma_snd_pcm_avail_proc _snd_pcm_avail = snd_pcm_avail;
ma_snd_pcm_avail_update_proc _snd_pcm_avail_update = snd_pcm_avail_update;
ma_snd_pcm_wait_proc _snd_pcm_wait = snd_pcm_wait;
ma_snd_pcm_nonblock_proc _snd_pcm_nonblock = snd_pcm_nonblock;
ma_snd_pcm_info_proc _snd_pcm_info = snd_pcm_info;
ma_snd_pcm_info_sizeof_proc _snd_pcm_info_sizeof = snd_pcm_info_sizeof;
ma_snd_pcm_info_get_name_proc _snd_pcm_info_get_name = snd_pcm_info_get_name;
ma_snd_pcm_poll_descriptors _snd_pcm_poll_descriptors = snd_pcm_poll_descriptors;
ma_snd_pcm_poll_descriptors_count _snd_pcm_poll_descriptors_count = snd_pcm_poll_descriptors_count;
ma_snd_pcm_poll_descriptors_revents _snd_pcm_poll_descriptors_revents = snd_pcm_poll_descriptors_revents;
ma_snd_config_update_free_global_proc _snd_config_update_free_global = snd_config_update_free_global;
pContext->alsa.snd_pcm_open = (ma_proc)_snd_pcm_open;
@@ -20950,6 +21126,7 @@ static ma_result ma_context_init__alsa(ma_context* pContext, const ma_context_co
pContext->alsa.snd_pcm_start = (ma_proc)_snd_pcm_start;
pContext->alsa.snd_pcm_drop = (ma_proc)_snd_pcm_drop;
pContext->alsa.snd_pcm_drain = (ma_proc)_snd_pcm_drain;
pContext->alsa.snd_pcm_reset = (ma_proc)_snd_pcm_reset;
pContext->alsa.snd_device_name_hint = (ma_proc)_snd_device_name_hint;
pContext->alsa.snd_device_name_get_hint = (ma_proc)_snd_device_name_get_hint;
pContext->alsa.snd_card_get_index = (ma_proc)_snd_card_get_index;
@@ -20962,9 +21139,13 @@ static ma_result ma_context_init__alsa(ma_context* pContext, const ma_context_co
pContext->alsa.snd_pcm_avail = (ma_proc)_snd_pcm_avail;
pContext->alsa.snd_pcm_avail_update = (ma_proc)_snd_pcm_avail_update;
pContext->alsa.snd_pcm_wait = (ma_proc)_snd_pcm_wait;
pContext->alsa.snd_pcm_nonblock = (ma_proc)_snd_pcm_nonblock;
pContext->alsa.snd_pcm_info = (ma_proc)_snd_pcm_info;
pContext->alsa.snd_pcm_info_sizeof = (ma_proc)_snd_pcm_info_sizeof;
pContext->alsa.snd_pcm_info_get_name = (ma_proc)_snd_pcm_info_get_name;
pContext->alsa.snd_pcm_poll_descriptors = (ma_proc)_snd_pcm_poll_descriptors;
pContext->alsa.snd_pcm_poll_descriptors_count = (ma_proc)_snd_pcm_poll_descriptors_count;
pContext->alsa.snd_pcm_poll_descriptors_revents = (ma_proc)_snd_pcm_poll_descriptors_revents;
pContext->alsa.snd_config_update_free_global = (ma_proc)_snd_config_update_free_global;
#endif
@@ -20985,6 +21166,7 @@ static ma_result ma_context_init__alsa(ma_context* pContext, const ma_context_co
pCallbacks->onDeviceRead = ma_device_read__alsa;
pCallbacks->onDeviceWrite = ma_device_write__alsa;
pCallbacks->onDeviceDataLoop = NULL;
pCallbacks->onDeviceDataLoopWakeup = ma_device_data_loop_wakeup__alsa;
return MA_SUCCESS;
}
@@ -64587,6 +64769,7 @@ REVISION HISTORY
v0.10.34 - TBD
- WASAPI: Fix a bug where a result code is not getting checked at initialization time.
- WASAPI: Bug fixes for loopback mode.
- ALSA: Fix a possible deadlock when stopping devices.
- Mark devices as default on the null backend.
v0.10.33 - 2021-04-04