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 4d2a4c6641aa3b7a250e0dcab291ff1ce5fcee43..753943e46d6269fd605083456fa6f100bb1fb865 100644 (file)
--- a/src/backend/storage/lmgr/spin.c
+++ b/src/backend/storage/lmgr/spin.c
@@ -106,7 +106,7 @@ SpinlockSemaInit(void)
 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;
 }