From: Keir Fraser Date: Mon, 7 Apr 2014 13:28:52 +0000 (+0100) Subject: call_rcu threads should clear their PAUSED flag when they unpause X-Git-Tag: v0.9.0~94 X-Git-Url: https://git.liburcu.org/?p=urcu.git;a=commitdiff_plain;h=fc236e5edb83c2273e251be4cd659f47491cc90c;hp=d6aefcd1538d2369be506b7a042109945c9b6dab call_rcu threads should clear their PAUSED flag when they unpause And call_rcu_after_fork_parent should spin-wait on this. Otherwise a second fork in the parent will see the PAUSED flags already set and call_rcu_before_fork will not correctly wait for the call_rcu threads to quiesce on this second occasion. Fixes #786 Signed-off-by: Keir Fraser Signed-off-by: Mathieu Desnoyers --- diff --git a/urcu-call-rcu-impl.h b/urcu-call-rcu-impl.h index 10c4f3e..c2e175b 100644 --- a/urcu-call-rcu-impl.h +++ b/urcu-call-rcu-impl.h @@ -308,6 +308,8 @@ static void *call_rcu_thread(void *arg) uatomic_or(&crdp->flags, URCU_CALL_RCU_PAUSED); while ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_PAUSE) != 0) poll(NULL, 0, 1); + uatomic_and(&crdp->flags, ~URCU_CALL_RCU_PAUSED); + cmm_smp_mb__after_uatomic_and(); rcu_register_thread(); } @@ -872,6 +874,10 @@ void call_rcu_after_fork_parent(void) cds_list_for_each_entry(crdp, &call_rcu_data_list, list) uatomic_and(&crdp->flags, ~URCU_CALL_RCU_PAUSE); + cds_list_for_each_entry(crdp, &call_rcu_data_list, list) { + while ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_PAUSED) != 0) + poll(NULL, 0, 1); + } call_rcu_unlock(&call_rcu_mutex); }