Paul Gofman : ntdll: Pre-check entry->addr before taking a spin lock in RtlWaitOnAddress().

[Alexandre Julliard]

Module: wine
Branch: master
Commit: e00cbef06d8df1c5aeed3bcabc3dfe660a21fa1d
URL:    https://gitlab.winehq.org/wine/wine/-/commit/e00cbef06d8df1c5aeed3bcabc3dfe6...

Author: Paul Gofman 
Date:   Thu Sep 21 16:29:14 2023 -0600

ntdll: Pre-check entry->addr before taking a spin lock in RtlWaitOnAddress().

---

dlls/ntdll/sync.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/dlls/ntdll/sync.c b/dlls/ntdll/sync.c
index 495514a1298..efc820624bb 100644
--- a/dlls/ntdll/sync.c
+++ b/dlls/ntdll/sync.c
@@ -898,11 +898,14 @@ NTSTATUS WINAPI RtlWaitOnAddress( const void *addr, const void *cmp, SIZE_T size

ret = NtWaitForAlertByThreadId( NULL, timeout );

-    spin_lock( &queue->lock );
-    /* We may have already been removed by a call to RtlWakeAddressSingle(). */
+    /* We may have already been removed by a call to RtlWakeAddressSingle() or RtlWakeAddressAll(). */
     if (entry.addr)
-        list_remove( &entry.entry );
-    spin_unlock( &queue->lock );
+    {
+        spin_lock( &queue->lock );
+        if (entry.addr)
+            list_remove( &entry.entry );
+        spin_unlock( &queue->lock );
+    }

TRACE("returning %#lx\n", ret);