From c10a445944b716f0f28c3d63f064a12e7b62ba92 Mon Sep 17 00:00:00 2001
From: Andre Noll <maan@systemlinux.org>
Date: Thu, 30 Jan 2014 22:51:44 +0100
Subject: [PATCH] ao_write: Check return value of pthread functions.
Although pthread_cond_wait() and pthread_cond_signal() should never
fail on our setup, let's be conservative here and check the return
value anyway.
This patch also adds some comments and removes a few lines of code
which were commented out since day one of the ao writer.
---
ao_write.c | 25 ++++++++++++++++---------
1 file changed, 16 insertions(+), 9 deletions(-)
diff --git a/ao_write.c b/ao_write.c
index 12ab77fe..d1d62a6d 100644
--- a/ao_write.c
+++ b/ao_write.c
@@ -28,6 +28,7 @@ struct private_aow_data {
pthread_t thread;
pthread_attr_t attr;
+ /* The mutex and the condition variable serialize access to ->btrn */
pthread_mutex_t mutex;
pthread_cond_t data_available;
struct btr_node *thread_btrn;
@@ -224,10 +225,6 @@ __noreturn static void *aow_play(void *priv)
int ret;
for (;;) {
- /*
- * Lock mutex and wait for signal. pthread_cond_wait() will
- * automatically and atomically unlock mutex while it waits.
- */
pthread_mutex_lock(&pawd->mutex);
for (;;) {
ret = btr_node_status(btrn, wn->min_iqs, BTR_NT_LEAF);
@@ -243,10 +240,16 @@ __noreturn static void *aow_play(void *priv)
ret = -E_WRITE_COMMON_EOF;
goto unlock;
}
- //PARA_CRIT_LOG("waiting for data\n");
- //usleep(1000);
- //pthread_mutex_unlock(&pawd->mutex);
- pthread_cond_wait(&pawd->data_available, &pawd->mutex);
+ /*
+ * No data available, go to sleep and wait for the main
+ * thread to wake us up. pthread_cond_wait() unlocks
+ * the mutex while it waits and locks it again upon
+ * return.
+ */
+ ret = pthread_cond_wait(&pawd->data_available,
+ &pawd->mutex);
+ /* pthread_cond_wait() can never fail here */
+ assert(ret == 0);
}
pthread_mutex_unlock(&pawd->mutex);
assert(frames > 0);
@@ -358,7 +361,11 @@ static int aow_post_select(__a_unused struct sched *s,
ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF);
if (ret > 0) {
btr_pushdown(wn->btrn);
- pthread_cond_signal(&pawd->data_available);
+ if (pthread_cond_signal(&pawd->data_available) != 0) {
+ ret = -E_AO_PTHREAD;
+ PARA_ERROR_LOG("pthread_cond_signal() failed\n");
+ goto remove_thread_btrn;
+ }
}
pthread_mutex_unlock(&pawd->mutex);
if (ret >= 0)
--
2.39.5