* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
+#include <urcu/assert.h>
#include <urcu/uatomic.h>
#include <urcu/wfstack.h>
#include "urcu-die.h"
void urcu_adaptative_wake_up(struct urcu_wait_node *wait)
{
cmm_smp_mb();
- assert(uatomic_read(&wait->state) == URCU_WAIT_WAITING);
+ urcu_posix_assert(uatomic_read(&wait->state) == URCU_WAIT_WAITING);
uatomic_set(&wait->state, URCU_WAIT_WAKEUP);
if (!(uatomic_read(&wait->state) & URCU_WAIT_RUNNING)) {
if (futex_noasync(&wait->state, FUTEX_WAKE, 1,
goto skip_futex_wait;
caa_cpu_relax();
}
- while (futex_noasync(&wait->state, FUTEX_WAIT, URCU_WAIT_WAITING,
- NULL, NULL, 0)) {
+ while (uatomic_read(&wait->state) == URCU_WAIT_WAITING) {
+ if (!futex_noasync(&wait->state, FUTEX_WAIT, URCU_WAIT_WAITING, 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
+ * URCU_WAIT_WAITING (spurious wakeups). Check
+ * the value again in user-space to validate
+ * whether it really differs from
+ * URCU_WAIT_WAITING.
+ */
+ continue;
+ }
switch (errno) {
- case EWOULDBLOCK:
+ case EAGAIN:
/* Value already changed. */
goto skip_futex_wait;
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);
}
while (!(uatomic_read(&wait->state) & URCU_WAIT_TEARDOWN))
poll(NULL, 0, 10);
- assert(uatomic_read(&wait->state) & URCU_WAIT_TEARDOWN);
+ urcu_posix_assert(uatomic_read(&wait->state) & URCU_WAIT_TEARDOWN);
}
static inline