bluez-alsa: Added a patch to fix the crash at PCM close

This fixes the random crash at PCM close

Change-Id: I373e4b7e55d6d7d4c3be4a4a7a9f460c00758215
Signed-off-by: Thierry Bultel <thierry.bultel@iot.bzh>

2 files changed, 181 insertions, 2 deletions

diff --git a/meta-audio-4a-framework/recipes-connectivity/bluez-alsa/bluez-alsa/0004-Fixed-the-SIGSEGV-at-PCM-close.patch b/meta-audio-4a-framework/recipes-connectivity/bluez-alsa/bluez-alsa/0004-Fixed-the-SIGSEGV-at-PCM-close.patch
new file mode 100644
index 00000000..52dbf773
--- /dev/null
+++ b/meta-audio-4a-framework/recipes-connectivity/bluez-alsa/bluez-alsa/0004-Fixed-the-SIGSEGV-at-PCM-close.patch
@@ -0,0 +1,180 @@
+From 23a1f554565c0cb9fade1a8f86ab9a09bf3d04e7 Mon Sep 17 00:00:00 2001
+From: Thierry Bultel <thierry.bultel@iot.bzh>
+Date: Wed, 26 Dec 2018 10:06:38 +0100
+Subject: [PATCH] Fixed the SIGSEGV at PCM close
+
+There is a (still not identified) race condition at PCM
+close, producing a SIGSEGV when pthread_cancel is called.
+Instead of proposing a trick with pthread_setcancelstate,
+this fix introduces a cancellation pipe, on which the io_thread
+polls. This guaranties a better, safer, exit path.
+
+Signed-off-by: Thierry Bultel <thierry.bultel@iot.bzh>
+---
+ src/asound/bluealsa-pcm.c | 82 +++++++++++++++++++++++++++++++++++++++++------
+ 1 file changed, 72 insertions(+), 10 deletions(-)
+
+diff --git a/src/asound/bluealsa-pcm.c b/src/asound/bluealsa-pcm.c
+index 2136964..013aebb 100644
+--- a/src/asound/bluealsa-pcm.c
++++ b/src/asound/bluealsa-pcm.c
+@@ -67,6 +67,8 @@ struct bluealsa_pcm {
+ 	snd_pcm_uframes_t io_hw_boundary;
+ 	snd_pcm_uframes_t io_hw_ptr;
+ 
++	int cancelPipe[2];
++
+ };
+ 
+ 
+@@ -107,7 +109,9 @@ static void *io_thread(void *arg) {
+ 	struct asrsync asrs;
+ 	asrsync_init(&asrs, io->rate);
+ 
+-	debug("Starting IO loop");
++	const char * type = io->stream== SND_PCM_STREAM_CAPTURE?"CAPTURE":"PLAYBACK";
++
++	debug("------------ Starting IO loop (%s)-----------------------", type);
+ 	for (;;) {
+ 
+ 		int tmp;
+@@ -124,6 +128,11 @@ static void *io_thread(void *arg) {
+ 			debug("IO thread resumed: %d", io->state);
+ 		}
+ 
++		if (pcm->io_started == false) {
++			debug("io_thread not started -> exit");
++			goto final;
++		}
++
+ 		snd_pcm_uframes_t io_ptr = pcm->io_ptr;
+ 		snd_pcm_uframes_t io_buffer_size = io->buffer_size;
+ 		snd_pcm_uframes_t io_hw_ptr = pcm->io_hw_ptr;
+@@ -152,21 +161,44 @@ static void *io_thread(void *arg) {
+ 		if (io_hw_ptr >= io_hw_boundary)
+ 			io_hw_ptr -= io_hw_boundary;
+ 
++		struct pollfd fds[2];
++
++		fds[0].fd = pcm->pcm_fd;
++		fds[1].fd = pcm->cancelPipe[0];
++
++		if (io->stream == SND_PCM_STREAM_CAPTURE)
++			fds[0].events |= POLLIN;
++		else
++			fds[0].events |= POLLOUT;
++
++		fds[1].events = POLLIN | POLLHUP;
++
+ 		if (io->stream == SND_PCM_STREAM_CAPTURE) {
+ 
+ 			/* Read the whole period "atomically". This will assure, that frames
+ 			 * are not fragmented, so the pointer can be correctly updated. */
+-			while (len != 0 && (ret = read(pcm->pcm_fd, head, len)) != 0) {
++			while (len != 0 &&
++					pcm->io_started) {
++
++				int pollres = poll(fds, 2, -1);
++
++				if ((fds[1].revents & POLLIN) != 0) {
++					debug("io_thread: CANCELLED");
++					goto final;
++				}
++
++				ret = read(pcm->pcm_fd, head, len);
+ 				if (ret == -1) {
+-					if (errno == EINTR)
+-						continue;
++					if (errno == EINTR) {
++						break;
++					}
+ 					SNDERR("PCM FIFO read error: %s", strerror(errno));
+ 					goto final;
+ 				}
+ 				head += ret;
+ 				len -= ret;
+-			}
+ 
++			}
+ 			if (ret == 0)
+ 				goto final;
+ 
+@@ -182,9 +214,18 @@ static void *io_thread(void *arg) {
+ 
+ 			/* Perform atomic write - see the explanation above. */
+ 			do {
++
++				int pollres = poll(fds, 2, -1);
++
++				if ((fds[1].revents & POLLIN) != 0) {
++					debug("io_thread: CANCELLED");
++					goto final;
++				}
++
+ 				if ((ret = write(pcm->pcm_fd, head, len)) == -1) {
+-					if (errno == EINTR)
+-						continue;
++					if (errno == EINTR) {
++						break;
++					}
+ 					SNDERR("PCM FIFO write error: %s", strerror(errno));
+ 					goto final;
+ 				}
+@@ -251,12 +292,24 @@ static int bluealsa_start(snd_pcm_ioplug_t *io) {
+ 
+ static int bluealsa_stop(snd_pcm_ioplug_t *io) {
+ 	struct bluealsa_pcm *pcm = io->private_data;
+-	debug("Stopping");
++	debug("Stopping %p", pcm);
++	if (!pcm) {
++		debug("PCM ALREADY CLOSED !");
++		return 0;
++	}
+ 	if (pcm->io_started) {
+ 		pcm->io_started = false;
+-		pthread_cancel(pcm->io_thread);
++
++		char dummy = 0;
++
++		if (write(pcm->cancelPipe[1], &dummy, sizeof(dummy)) < 0)
++			debug("Failed to write to the cancellation pipe");
++
+ 		pthread_join(pcm->io_thread, NULL);
+ 	}
++done:
++	debug("Stop done");
++
+ 	return 0;
+ }
+ 
+@@ -269,10 +322,14 @@ static snd_pcm_sframes_t bluealsa_pointer(snd_pcm_ioplug_t *io) {
+ 
+ static int bluealsa_close(snd_pcm_ioplug_t *io) {
+ 	struct bluealsa_pcm *pcm = io->private_data;
+-	debug("Closing plugin");
++	debug("Closing plugin %p", pcm);
+ 	close(pcm->fd);
+ 	close(pcm->event_fd);
++	close(pcm->cancelPipe[0]);
++	close(pcm->cancelPipe[1]);
+ 	free(pcm);
++	io->private_data = NULL;
++	debug("PCM closed");
+ 	return 0;
+ }
+ 
+@@ -649,6 +706,11 @@ SND_PCM_PLUGIN_DEFINE_FUNC(bluealsa) {
+ 	pcm->pcm_fd = -1;
+ 	pcm->delay_ex = delay;
+ 
++	if (pipe(pcm->cancelPipe) == -1) {
++		SNDERR("BlueALSA failed to create cancellation pipe: %s", strerror(errno));
++		ret = -errno;
++	}
++
+ 	if ((pcm->fd = bluealsa_open(interface)) == -1) {
+ 		SNDERR("BlueALSA connection failed: %s", strerror(errno));
+ 		ret = -errno;
+-- 
+2.16.4
+
diff --git a/meta-audio-4a-framework/recipes-connectivity/bluez-alsa/bluez-alsa_git.bbappend b/meta-audio-4a-framework/recipes-connectivity/bluez-alsa/bluez-alsa_git.bbappend
index 43e4632f..8c67037f 100644
--- a/meta-audio-4a-framework/recipes-connectivity/bluez-alsa/bluez-alsa_git.bbappend
+++ b/meta-audio-4a-framework/recipes-connectivity/bluez-alsa/bluez-alsa_git.bbappend
@@ -7,5 +7,4 @@ FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
 SRC_URI += "file://0001-build-and-link-with-a-shared-library.patch"
 SRC_URI += "file://0002-log-add-calling-function-name.patch"
 SRC_URI += "file://0003-increased-the-number-of-connexions-to-16.patch"
-
-
+SRC_URI += "file://0004-Fixed-the-SIGSEGV-at-PCM-close.patch"