From: Andres Freund <andres@anarazel.de>
Date: Mon, 8 Jun 2020 22:25:49 +0000 (-0700)
Subject: spinlock emulation: Fix bug when more than INT_MAX spinlocks are initialized.
X-Git-Tag: REL9_6_19~47
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=660622053419fbb776c7218f2110500b3b034b35;p=thirdparty%2Fpostgresql.git

spinlock emulation: Fix bug when more than INT_MAX spinlocks are initialized.

Once the counter goes negative we ended up with spinlocks that errored
out on first use (due to check in tas_sema).

Author: Andres Freund
Reviewed-By: Robert Haas
Discussion: https://postgr.es/m/20200606023103.avzrctgv7476xj7i@alap3.anarazel.de
Backpatch: 9.5-
---

diff --git a/src/backend/storage/lmgr/spin.c b/src/backend/storage/lmgr/spin.c
index 50391414305..9b73e7e1851 100644
--- a/src/backend/storage/lmgr/spin.c
+++ b/src/backend/storage/lmgr/spin.c
@@ -97,7 +97,7 @@ SpinlockSemaInit(PGSemaphore spinsemas)
 void
 s_init_lock_sema(volatile slock_t *lock, bool nested)
 {
-	static int	counter = 0;
+	static uint32 counter = 0;
 
 	*lock = ((++counter) % NUM_SPINLOCK_SEMAPHORES) + 1;
 }