Fix: workqueue: remove unused variable "ret"

[urcu.git] / src / workqueue.c

diff --git a/src/workqueue.c b/src/workqueue.c
index 72170012eafc2fb925f885b9a666be610901ec3f..b6361adafb5b97f2116ac9b864111c8cc2a55d92 100644 (file)
--- a/src/workqueue.c
+++ b/src/workqueue.c
@@ -25,7 +25,6 @@
 #include <stdio.h>
 #include <pthread.h>
 #include <signal.h>
-#include <assert.h>
 #include <stdlib.h>
 #include <stdint.h>
 #include <string.h>
@@ -36,6 +35,7 @@
 #include <sched.h>
 
 #include "compat-getcpu.h"
+#include <urcu/assert.h>
 #include <urcu/wfcqueue.h>
 #include <urcu/pointer.h>
 #include <urcu/list.h>
@@ -121,7 +121,7 @@ static int set_thread_cpu_affinity(struct urcu_workqueue *workqueue)
        return ret;
 }
 #else
-static int set_thread_cpu_affinity(struct urcu_workqueue *workqueue)
+static int set_thread_cpu_affinity(struct urcu_workqueue *workqueue __attribute__((unused)))
 {
        return 0;
 }
@@ -131,16 +131,25 @@ static void futex_wait(int32_t *futex)
 {
        /* Read condition before read futex */
        cmm_smp_mb();
-       if (uatomic_read(futex) != -1)
-               return;
-       while (futex_async(futex, FUTEX_WAIT, -1, NULL, NULL, 0)) {
+       while (uatomic_read(futex) == -1) {
+               if (!futex_async(futex, FUTEX_WAIT, -1, NULL, NULL, 0)) {
+                       /*
+                        * Prior queued wakeups queued by unrelated code
+                        * using the same address can cause futex wait to
+                        * return 0 even through the futex value is still
+                        * -1 (spurious wakeups). Check the value again
+                        * in user-space to validate whether it really
+                        * differs from -1.
+                        */
+                       continue;
+               }
                switch (errno) {
-               case EWOULDBLOCK:
+               case EAGAIN:
                        /* Value already changed. */
                        return;
                case EINTR:
                        /* Retry if interrupted by signal. */
-                       break;  /* Get out of switch. */
+                       break;  /* Get out of switch. Check again. */
                default:
                        /* Unexpected error. */
                        urcu_die(errno);
@@ -210,8 +219,8 @@ static void *workqueue_thread(void *arg)
                cds_wfcq_init(&cbs_tmp_head, &cbs_tmp_tail);
                splice_ret = __cds_wfcq_splice_blocking(&cbs_tmp_head,
                        &cbs_tmp_tail, &workqueue->cbs_head, &workqueue->cbs_tail);
-               assert(splice_ret != CDS_WFCQ_RET_WOULDBLOCK);
-               assert(splice_ret != CDS_WFCQ_RET_DEST_NON_EMPTY);
+               urcu_posix_assert(splice_ret != CDS_WFCQ_RET_WOULDBLOCK);
+               urcu_posix_assert(splice_ret != CDS_WFCQ_RET_DEST_NON_EMPTY);
                if (splice_ret != CDS_WFCQ_RET_SRC_EMPTY) {
                        if (workqueue->grace_period_fct)
                                workqueue->grace_period_fct(workqueue, workqueue->priv);
@@ -336,7 +345,7 @@ void urcu_workqueue_destroy(struct urcu_workqueue *workqueue)
        if (urcu_workqueue_destroy_worker(workqueue)) {
                urcu_die(errno);
        }
-       assert(cds_wfcq_empty(&workqueue->cbs_head, &workqueue->cbs_tail));
+       urcu_posix_assert(cds_wfcq_empty(&workqueue->cbs_head, &workqueue->cbs_tail));
        free(workqueue);
 }