From 9fbb46cd8909d8058d32421e0e41c223d710d7d4 Mon Sep 17 00:00:00 2001 From: Thomas Munro Date: Sat, 27 Feb 2021 15:36:22 +1300 Subject: [PATCH v4 2/3] Allow condition variables to be used in interrupt code. Adjust the condition variable sleep loop to work correctly when code reached by its internal CHECK_FOR_INTERRUPTS() call interacts with another condition variable. There are no such cases currently, but a proposed patch would do this. Discussion: https://postgr.es/m/CA+hUKGLdemy2gBm80kz20GTe6hNVwoErE8KwcJk6-U56oStjtg@mail.gmail.com --- src/backend/storage/lmgr/condition_variable.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/src/backend/storage/lmgr/condition_variable.c b/src/backend/storage/lmgr/condition_variable.c index 0a61ff0031..80d70c154c 100644 --- a/src/backend/storage/lmgr/condition_variable.c +++ b/src/backend/storage/lmgr/condition_variable.c @@ -165,8 +165,6 @@ ConditionVariableTimedSleep(ConditionVariable *cv, long timeout, /* Reset latch before examining the state of the wait list. */ ResetLatch(MyLatch); - CHECK_FOR_INTERRUPTS(); - /* * If this process has been taken out of the wait list, then we know * that it has been signaled by ConditionVariableSignal (or @@ -190,6 +188,15 @@ ConditionVariableTimedSleep(ConditionVariable *cv, long timeout, } SpinLockRelease(&cv->mutex); + /* + * Check for interrupts, and return spuriously if that caused the + * current sleep target to change (meaning that interrupt handler code + * waited for a different condition variable). + */ + CHECK_FOR_INTERRUPTS(); + if (cv != cv_sleep_target) + done = true; + /* We were signaled, so return */ if (done) return false; -- 2.30.0