lkml.org 
[lkml]   [2021]   [Jan]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] drm/syncobj: make lockdep complain on WAIT_FOR_SUBMIT v2
Date
DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT can't be used when we hold locks
since we are basically waiting for userspace to do something.

Holding a lock while doing so can trivial deadlock with page faults
etc...

So make lockdep complain when a driver tries to do this.

v2: Add lockdep_assert_none_held() macro.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
drivers/gpu/drm/drm_syncobj.c | 7 +++++++
include/linux/lockdep.h | 5 +++++
2 files changed, 12 insertions(+)

diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index 6e74e6745eca..f51458615158 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -387,6 +387,13 @@ int drm_syncobj_find_fence(struct drm_file *file_private,
if (!syncobj)
return -ENOENT;

+ /* Waiting for userspace with locks help is illegal cause that can
+ * trivial deadlock with page faults for example. Make lockdep complain
+ * about it early on.
+ */
+ if (flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT)
+ lockdep_assert_none_held_once();
+
*fence = drm_syncobj_fence_get(syncobj);
drm_syncobj_put(syncobj);

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index b9e9adec73e8..6eb117c0d0f3 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -310,6 +310,10 @@ extern void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie);
WARN_ON_ONCE(debug_locks && !lockdep_is_held(l)); \
} while (0)

+#define lockdep_assert_none_held_once() do { \
+ WARN_ON_ONCE(debug_locks && current->lockdep_depth); \
+ } while (0)
+
#define lockdep_recursing(tsk) ((tsk)->lockdep_recursion)

#define lockdep_pin_lock(l) lock_pin_lock(&(l)->dep_map)
@@ -387,6 +391,7 @@ extern int lockdep_is_held(const void *);
#define lockdep_assert_held_write(l) do { (void)(l); } while (0)
#define lockdep_assert_held_read(l) do { (void)(l); } while (0)
#define lockdep_assert_held_once(l) do { (void)(l); } while (0)
+#define lockdep_assert_none_held_once() do { } while (0)

#define lockdep_recursing(tsk) (0)

--
2.25.1
\
 
 \ /
  Last update: 2021-01-18 19:09    [W:0.072 / U:0.012 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site