From 2216cd8a1513120b7814a736b344f689dc75b37b Mon Sep 17 00:00:00 2001 From: Thomas Munro Date: Sat, 21 Oct 2023 17:40:26 +1300 Subject: [PATCH] Fix min_dynamic_shared_memory on Windows. When min_dynamic_shared_memory is set above 0, we try to find space in a region of the main shared memory area instead of calling out to dsm_impl_XXX() routines. The dsm_pin_segment() and dsm_unpin_segment() routines had a bug: they called dsm_impl_XXX() routines even for main region segments. Nobody noticed before now because those routines do nothing on Unix, but on Windows they'd fail while attempting to duplicate an invalid Windows HANDLE. Add the missing gating. Back-patch to 14, where commit 84b1c63a added this feature. Fixes pgsql-bugs bug #18165. Reported-by: Maxime Boyer Discussion: https://postgr.es/m/18165-bf4f525cea6e51de%40postgresql.org --- src/backend/storage/ipc/dsm.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/src/backend/storage/ipc/dsm.c b/src/backend/storage/ipc/dsm.c index 10b029bb16..cef547bb6c 100644 --- a/src/backend/storage/ipc/dsm.c +++ b/src/backend/storage/ipc/dsm.c @@ -938,7 +938,8 @@ dsm_pin_segment(dsm_segment *seg) LWLockAcquire(DynamicSharedMemoryControlLock, LW_EXCLUSIVE); if (dsm_control->item[seg->control_slot].pinned) elog(ERROR, "cannot pin a segment that is already pinned"); - dsm_impl_pin_segment(seg->handle, seg->impl_private, &handle); + if (!is_main_region_dsm_handle(seg->handle)) + dsm_impl_pin_segment(seg->handle, seg->impl_private, &handle); dsm_control->item[seg->control_slot].pinned = true; dsm_control->item[seg->control_slot].refcnt++; dsm_control->item[seg->control_slot].impl_private_pm_handle = handle; @@ -995,8 +996,9 @@ dsm_unpin_segment(dsm_handle handle) * releasing the lock, because impl_private_pm_handle may get modified by * dsm_impl_unpin_segment. */ - dsm_impl_unpin_segment(handle, - &dsm_control->item[control_slot].impl_private_pm_handle); + if (!is_main_region_dsm_handle(handle)) + dsm_impl_unpin_segment(handle, + &dsm_control->item[control_slot].impl_private_pm_handle); /* Note that 1 means no references (0 means unused slot). */ if (--dsm_control->item[control_slot].refcnt == 1) -- 2.42.0