* Losing affinity can be caused by CPU hotunplug/hotplug, or by
* cpuset(7).
*/
-#if HAVE_SCHED_SETAFFINITY
+#ifdef HAVE_SCHED_SETAFFINITY
static
int set_thread_cpu_affinity(struct call_rcu_data *crdp)
{
}
#else
static
-int set_thread_cpu_affinity(struct call_rcu_data *crdp)
+int set_thread_cpu_affinity(struct call_rcu_data *crdp __attribute__((unused)))
{
return 0;
}
{
/* Read call_rcu list before read futex */
cmm_smp_mb();
- if (uatomic_read(&crdp->futex) != -1)
- return;
- while (futex_async(&crdp->futex, FUTEX_WAIT, -1,
- NULL, NULL, 0)) {
+ while (uatomic_read(&crdp->futex) == -1) {
+ if (!futex_async(&crdp->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);
{
/* Read completion barrier count before read futex */
cmm_smp_mb();
- if (uatomic_read(&completion->futex) != -1)
- return;
- while (futex_async(&completion->futex, FUTEX_WAIT, -1,
- NULL, NULL, 0)) {
+ while (uatomic_read(&completion->futex) == -1) {
+ if (!futex_async(&completion->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);