From c10a445944b716f0f28c3d63f064a12e7b62ba92 Mon Sep 17 00:00:00 2001 From: Andre Noll 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) -- 2.39.2