Fix: handle sys_futex() FUTEX_WAIT interrupted by signal

[userspace-rcu.git] / urcu-call-rcu-impl.h

diff --git a/urcu-call-rcu-impl.h b/urcu-call-rcu-impl.h
index e70789a5906d6dec6f707025ec3db5895ea34b0f..6495f465e1fade0477179be441694751cbc8c473 100644 (file)
--- a/urcu-call-rcu-impl.h
+++ b/urcu-call-rcu-impl.h
@@ -235,9 +235,22 @@ static void call_rcu_wait(struct call_rcu_data *crdp)
 {
        /* Read call_rcu list before read futex */
        cmm_smp_mb();
-       if (uatomic_read(&crdp->futex) == -1)
-               futex_async(&crdp->futex, FUTEX_WAIT, -1,
-                     NULL, NULL, 0);
+       if (uatomic_read(&crdp->futex) != -1)
+               return;
+       while (futex_async(&crdp->futex, FUTEX_WAIT, -1,
+                       NULL, NULL, 0)) {
+               switch (errno) {
+               case EWOULDBLOCK:
+                       /* Value already changed. */
+                       return;
+               case EINTR:
+                       /* Retry if interrupted by signal. */
+                       break;  /* Get out of switch. */
+               default:
+                       /* Unexpected error. */
+                       urcu_die(errno);
+               }
+       }
 }
 
 static void call_rcu_wake_up(struct call_rcu_data *crdp)
@@ -246,8 +259,9 @@ static void call_rcu_wake_up(struct call_rcu_data *crdp)
        cmm_smp_mb();
        if (caa_unlikely(uatomic_read(&crdp->futex) == -1)) {
                uatomic_set(&crdp->futex, 0);
-               futex_async(&crdp->futex, FUTEX_WAKE, 1,
-                     NULL, NULL, 0);
+               if (futex_async(&crdp->futex, FUTEX_WAKE, 1,
+                               NULL, NULL, 0) < 0)
+                       urcu_die(errno);
        }
 }