Module Name: src
Committed By: riastradh
Date: Sun Dec 19 11:52:16 UTC 2021
Modified Files:
src/sys/external/bsd/drm2/dist/drm: drm_vblank.c
Log Message:
drm: Fix lock order reversal in merge botch.
Add a note reminding myself what the lock order is.
To generate a diff of this commit:
cvs rdiff -u -r1.8 -r1.9 src/sys/external/bsd/drm2/dist/drm/drm_vblank.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/external/bsd/drm2/dist/drm/drm_vblank.c
diff -u src/sys/external/bsd/drm2/dist/drm/drm_vblank.c:1.8 src/sys/external/bsd/drm2/dist/drm/drm_vblank.c:1.9
--- src/sys/external/bsd/drm2/dist/drm/drm_vblank.c:1.8 Sun Dec 19 11:48:42 2021
+++ src/sys/external/bsd/drm2/dist/drm/drm_vblank.c Sun Dec 19 11:52:16 2021
@@ -1,4 +1,4 @@
-/* $NetBSD: drm_vblank.c,v 1.8 2021/12/19 11:48:42 riastradh Exp $ */
+/* $NetBSD: drm_vblank.c,v 1.9 2021/12/19 11:52:16 riastradh Exp $ */
/*
* drm_irq.c IRQ and vblank support
@@ -27,7 +27,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: drm_vblank.c,v 1.8 2021/12/19 11:48:42 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: drm_vblank.c,v 1.9 2021/12/19 11:52:16 riastradh Exp $");
#include <linux/export.h>
#include <linux/moduleparam.h>
@@ -75,6 +75,8 @@ __KERNEL_RCSID(0, "$NetBSD: drm_vblank.c
* &drm_driver.max_vblank_count. In that case the vblank core only disables the
* vblanks after a timer has expired, which can be configured through the
* ``vblankoffdelay`` module parameter.
+ *
+ * Lock order: event_lock -> vbl_lock -> vblank_time_lock
*/
/* Retry timestamp calculation up to 3 times to satisfy
@@ -1875,14 +1877,14 @@ bool drm_handle_vblank(struct drm_device
spin_lock_irqsave(&dev->event_lock, irqflags);
+ spin_lock(&dev->vbl_lock);
+
/* Need timestamp lock to prevent concurrent execution with
* vblank enable/disable, as this would cause inconsistent
* or corrupted timestamps and vblank counts.
*/
spin_lock(&dev->vblank_time_lock);
- spin_lock(&dev->vbl_lock);
-
/* Vblank irq handling disabled. Nothing to do. */
if (!vblank->enabled) {
spin_unlock(&dev->vbl_lock);
