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[email protected]
Backpatch: 9.5-

diff --git a/src/backend/storage/lmgr/spin.c b/src/backend/storage/lmgr/spin.c
index 1ca718bfd9c957d922d367e146b2cc2ac5b28a4e..dfa47a723fa8e56275052ddc58b81c7c8902d640 100644 (file)
--- a/src/backend/storage/lmgr/spin.c
+++ b/src/backend/storage/lmgr/spin.c
@@ -91,7 +91,7 @@ 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;
 }