Revert "CRAS: use mutex lock to guard |sr| and |sr_buf|"

This reverts commit 9f329061a9b759b103c4a6103427d9f98c7723e6.

Reason for revert: proper fix in CL:5461198

Original change's description:
> CRAS: use mutex lock to guard |sr| and |sr_buf|
>
> There is a potential data race on the two variables where the audio
> thread can be using them while the main thread destructs them.
>
> BUG=b:333619168
> TEST=test scenario 2 in bug and verify no crash
>
> Change-Id: Ic1b3e453c39452b17224a7374fb0323e6a7775d1
> Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/adhd/+/5449295
> Commit-Queue: Jeremy Wu <jrwu@google.com>
> Tested-by: chromeos-cop-builder@chromeos-cop.iam.gserviceaccount.com <chromeos-cop-builder@chromeos-cop.iam.gserviceaccount.com>
> Reviewed-by: Cranel W <cranelw@chromium.org>

BUG=b:333619168

Change-Id: I4d97e84eb34162788865d98a773007d8f54d7a8a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/adhd/+/5465179
Reviewed-by: Hsinyu Chao <hychao@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Tested-by: chromeos-cop-builder@chromeos-cop.iam.gserviceaccount.com <chromeos-cop-builder@chromeos-cop.iam.gserviceaccount.com>
Reviewed-by: Cranel W <cranelw@chromium.org>
Commit-Queue: Jeremy Wu <jrwu@google.com>

1 files changed, 3 insertions, 18 deletions

diff --git a/cras/src/server/cras_fl_pcm_iodev.c b/cras/src/server/cras_fl_pcm_iodev.c
index f80d55bd..ccb92da6 100644
--- a/cras/src/server/cras_fl_pcm_iodev.c
+++ b/cras/src/server/cras_fl_pcm_iodev.c
@@ -6,7 +6,6 @@
 #include "cras/src/server/cras_fl_pcm_iodev.h"
 
 #include <errno.h>
-#include <pthread.h>
 #include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
@@ -110,9 +109,6 @@ struct fl_pcm_io {
   struct cras_sr* sr;
   // Buffer to hold the sr input pcm samples.
   struct byte_buffer* sr_buf;
-  // The mutex to protect |sr| and |sr_buf| from being destructed
-  // by the main thread during its processing in the audio thread.
-  pthread_mutex_t sr_mutex;
 };
 
 static int flush(const struct cras_iodev* iodev);
@@ -468,8 +464,6 @@ static int hfp_socket_read_write_cb(void* arg, int revents) {
 
   // Allow last read before handling error or hang-up events.
   if (revents & POLLIN) {
-    pthread_mutex_lock(&idev->sr_mutex);
-
     if (idev->sr) {
       swap_pcm_buf_and_sr_buf(idev);
       rc = hfp_read(idev);
@@ -483,10 +477,7 @@ static int hfp_socket_read_write_cb(void* arg, int revents) {
     if (idev->sr) {
       cras_sr_process(idev->sr, idev->sr_buf, idev->pcm_buf);
     }
-
-    pthread_mutex_unlock(&idev->sr_mutex);
   }
-
   if (revents & (POLLERR | POLLHUP)) {
     syslog(LOG_WARNING, "Error polling SCO socket, revents %d", revents);
     if (revents & POLLHUP) {
@@ -515,13 +506,9 @@ static int hfp_socket_read_write_cb(void* arg, int revents) {
 }
 
 static void fl_pcm_io_disable_cras_sr_bt(struct fl_pcm_io* fl_pcm_io) {
-  pthread_mutex_lock(&fl_pcm_io->sr_mutex);
-
   byte_buffer_destroy(&fl_pcm_io->sr_buf);
   cras_sr_destroy(fl_pcm_io->sr);
   fl_pcm_io->sr = NULL;
-
-  pthread_mutex_unlock(&fl_pcm_io->sr_mutex);
 }
 
 static int fl_pcm_io_get_sr_bt_model(struct fl_pcm_io* fl_pcm_io,
@@ -1242,12 +1229,10 @@ struct cras_iodev* hfp_pcm_iodev_create(struct cras_hfp* hfp,
     goto error;
   }
 
+  // At this point, we know which codec is preferred. This will usually
+  // be the negotiated codec, but the spec allows to fallback to CVSD,
+  // in which case this will be updated in |hfp_open_dev|.
   if (iodev->direction == CRAS_STREAM_INPUT) {
-    pthread_mutex_init(&hfpio->sr_mutex, NULL);
-
-    // At this point, we know which codec is preferred. This will usually
-    // be the negotiated codec, but the spec allows to fallback to CVSD,
-    // in which case this will be updated in |hfp_open_dev|.
     if (cras_floss_hfp_is_codec_format_supported(
             hfpio->hfp, HFP_CODEC_FORMAT_LC3_TRANSPARENT)) {
       iodev->active_node->btflags |= CRAS_BT_FLAG_SWB;