* [PATCH v2 0/2] locking/lockdep, drm: apply new lockdep assert in drm_auth.c
@ 2021-07-31 8:24 Desmond Cheong Zhi Xi
2021-07-31 8:24 ` [PATCH v2 1/2] locking/lockdep: Provide lockdep_assert{,_once}() helpers Desmond Cheong Zhi Xi
` (2 more replies)
0 siblings, 3 replies; 7+ messages in thread
From: Desmond Cheong Zhi Xi @ 2021-07-31 8:24 UTC (permalink / raw)
To: maarten.lankhorst, mripard, tzimmermann, airlied, daniel, peterz,
mingo, will, longman, boqun.feng
Cc: Desmond Cheong Zhi Xi, dri-devel, linux-kernel, skhan, gregkh,
linux-kernel-mentees
Hi,
Following a discussion on the patch ("drm: use the lookup lock in
drm_is_current_master") [1], Peter Zijlstra proposed new lockdep_assert
helpers to make it convenient to compose lockdep checks together.
This series includes the patch that introduces the new lockdep helpers,
then utilizes these helpers in drm_is_current_master_locked in the
following patch.
v1 -> v2:
Patch 2:
- Updated the kerneldoc on the lock design of drm_file.master to explain
the use of lockdep_assert(). As suggested by Boqun Feng.
Link: https://lore.kernel.org/lkml/20210722092929.244629-2-desmondcheongzx@gmail.com/ [1]
Best wishes,
Desmond
Desmond Cheong Zhi Xi (1):
drm: add lockdep assert to drm_is_current_master_locked
Peter Zijlstra (1):
locking/lockdep: Provide lockdep_assert{,_once}() helpers
drivers/gpu/drm/drm_auth.c | 6 +++---
include/drm/drm_file.h | 4 ++++
include/linux/lockdep.h | 41 +++++++++++++++++++-------------------
3 files changed, 28 insertions(+), 23 deletions(-)
--
2.25.1
^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH v2 1/2] locking/lockdep: Provide lockdep_assert{,_once}() helpers
2021-07-31 8:24 [PATCH v2 0/2] locking/lockdep, drm: apply new lockdep assert in drm_auth.c Desmond Cheong Zhi Xi
@ 2021-07-31 8:24 ` Desmond Cheong Zhi Xi
2021-08-02 9:49 ` Maarten Lankhorst
2021-07-31 8:24 ` [PATCH v2 2/2] drm: add lockdep assert to drm_is_current_master_locked Desmond Cheong Zhi Xi
2021-08-02 8:26 ` [PATCH v2 0/2] locking/lockdep, drm: apply new lockdep assert in drm_auth.c Daniel Vetter
2 siblings, 1 reply; 7+ messages in thread
From: Desmond Cheong Zhi Xi @ 2021-07-31 8:24 UTC (permalink / raw)
To: maarten.lankhorst, mripard, tzimmermann, airlied, daniel, peterz,
mingo, will, longman, boqun.feng
Cc: Desmond Cheong Zhi Xi, dri-devel, linux-kernel, skhan, gregkh,
linux-kernel-mentees
From: Peter Zijlstra <peterz@infradead.org>
Extract lockdep_assert{,_once}() helpers to more easily write composite
assertions like, for example:
lockdep_assert(lockdep_is_held(&drm_device.master_mutex) ||
lockdep_is_held(&drm_file.master_lookup_lock));
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>
Acked-by: Boqun Feng <boqun.feng@gmail.com>
Acked-by: Waiman Long <longman@redhat.com>
---
include/linux/lockdep.h | 41 +++++++++++++++++++++--------------------
1 file changed, 21 insertions(+), 20 deletions(-)
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 5cf387813754..9fe165beb0f9 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -306,31 +306,29 @@ extern void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie);
#define lockdep_depth(tsk) (debug_locks ? (tsk)->lockdep_depth : 0)
-#define lockdep_assert_held(l) do { \
- WARN_ON(debug_locks && \
- lockdep_is_held(l) == LOCK_STATE_NOT_HELD); \
- } while (0)
+#define lockdep_assert(cond) \
+ do { WARN_ON(debug_locks && !(cond)); } while (0)
-#define lockdep_assert_not_held(l) do { \
- WARN_ON(debug_locks && \
- lockdep_is_held(l) == LOCK_STATE_HELD); \
- } while (0)
+#define lockdep_assert_once(cond) \
+ do { WARN_ON_ONCE(debug_locks && !(cond)); } while (0)
-#define lockdep_assert_held_write(l) do { \
- WARN_ON(debug_locks && !lockdep_is_held_type(l, 0)); \
- } while (0)
+#define lockdep_assert_held(l) \
+ lockdep_assert(lockdep_is_held(l) != LOCK_STATE_NOT_HELD)
-#define lockdep_assert_held_read(l) do { \
- WARN_ON(debug_locks && !lockdep_is_held_type(l, 1)); \
- } while (0)
+#define lockdep_assert_not_held(l) \
+ lockdep_assert(lockdep_is_held(l) != LOCK_STATE_HELD)
-#define lockdep_assert_held_once(l) do { \
- WARN_ON_ONCE(debug_locks && !lockdep_is_held(l)); \
- } while (0)
+#define lockdep_assert_held_write(l) \
+ lockdep_assert(lockdep_is_held_type(l, 0))
-#define lockdep_assert_none_held_once() do { \
- WARN_ON_ONCE(debug_locks && current->lockdep_depth); \
- } while (0)
+#define lockdep_assert_held_read(l) \
+ lockdep_assert(lockdep_is_held_type(l, 1))
+
+#define lockdep_assert_held_once(l) \
+ lockdep_assert_once(lockdep_is_held(l) != LOCK_STATE_NOT_HELD)
+
+#define lockdep_assert_none_held_once() \
+ lockdep_assert_once(!current->lockdep_depth)
#define lockdep_recursing(tsk) ((tsk)->lockdep_recursion)
@@ -407,6 +405,9 @@ extern int lock_is_held(const void *);
extern int lockdep_is_held(const void *);
#define lockdep_is_held_type(l, r) (1)
+#define lockdep_assert(c) do { } while (0)
+#define lockdep_assert_once(c) do { } while (0)
+
#define lockdep_assert_held(l) do { (void)(l); } while (0)
#define lockdep_assert_not_held(l) do { (void)(l); } while (0)
#define lockdep_assert_held_write(l) do { (void)(l); } while (0)
--
2.25.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH v2 2/2] drm: add lockdep assert to drm_is_current_master_locked
2021-07-31 8:24 [PATCH v2 0/2] locking/lockdep, drm: apply new lockdep assert in drm_auth.c Desmond Cheong Zhi Xi
2021-07-31 8:24 ` [PATCH v2 1/2] locking/lockdep: Provide lockdep_assert{,_once}() helpers Desmond Cheong Zhi Xi
@ 2021-07-31 8:24 ` Desmond Cheong Zhi Xi
2021-08-02 8:26 ` [PATCH v2 0/2] locking/lockdep, drm: apply new lockdep assert in drm_auth.c Daniel Vetter
2 siblings, 0 replies; 7+ messages in thread
From: Desmond Cheong Zhi Xi @ 2021-07-31 8:24 UTC (permalink / raw)
To: maarten.lankhorst, mripard, tzimmermann, airlied, daniel, peterz,
mingo, will, longman, boqun.feng
Cc: Desmond Cheong Zhi Xi, dri-devel, linux-kernel, skhan, gregkh,
linux-kernel-mentees
In drm_is_current_master_locked, accessing drm_file.master should be
protected by either drm_file.master_lookup_lock or
drm_device.master_mutex. This was previously awkward to assert with
lockdep.
Following patch ("locking/lockdep: Provide lockdep_assert{,_once}()
helpers"), this assertion is now convenient. So we add in the
assertion and explain this lock design in the kerneldoc.
Signed-off-by: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>
Acked-by: Boqun Feng <boqun.feng@gmail.com>
Acked-by: Waiman Long <longman@redhat.com>
---
drivers/gpu/drm/drm_auth.c | 6 +++---
include/drm/drm_file.h | 4 ++++
2 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c
index 9c24b8cc8e36..6f4d7ff23c80 100644
--- a/drivers/gpu/drm/drm_auth.c
+++ b/drivers/gpu/drm/drm_auth.c
@@ -63,9 +63,9 @@
static bool drm_is_current_master_locked(struct drm_file *fpriv)
{
- /* Either drm_device.master_mutex or drm_file.master_lookup_lock
- * should be held here.
- */
+ lockdep_assert_once(lockdep_is_held(&fpriv->master_lookup_lock) ||
+ lockdep_is_held(&fpriv->minor->dev->master_mutex));
+
return fpriv->is_master && drm_lease_owner(fpriv->master) == fpriv->minor->dev->master;
}
diff --git a/include/drm/drm_file.h b/include/drm/drm_file.h
index 726cfe0ff5f5..a3acb7ac3550 100644
--- a/include/drm/drm_file.h
+++ b/include/drm/drm_file.h
@@ -233,6 +233,10 @@ struct drm_file {
* this only matches &drm_device.master if the master is the currently
* active one.
*
+ * To update @master, both &drm_device.master_mutex and
+ * @master_lookup_lock need to be held, therefore holding either of
+ * them is safe and enough for the read side.
+ *
* When dereferencing this pointer, either hold struct
* &drm_device.master_mutex for the duration of the pointer's use, or
* use drm_file_get_master() if struct &drm_device.master_mutex is not
--
2.25.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH v2 0/2] locking/lockdep, drm: apply new lockdep assert in drm_auth.c
2021-07-31 8:24 [PATCH v2 0/2] locking/lockdep, drm: apply new lockdep assert in drm_auth.c Desmond Cheong Zhi Xi
2021-07-31 8:24 ` [PATCH v2 1/2] locking/lockdep: Provide lockdep_assert{,_once}() helpers Desmond Cheong Zhi Xi
2021-07-31 8:24 ` [PATCH v2 2/2] drm: add lockdep assert to drm_is_current_master_locked Desmond Cheong Zhi Xi
@ 2021-08-02 8:26 ` Daniel Vetter
2021-08-02 9:42 ` Peter Zijlstra
2021-08-02 10:44 ` Desmond Cheong Zhi Xi
2 siblings, 2 replies; 7+ messages in thread
From: Daniel Vetter @ 2021-08-02 8:26 UTC (permalink / raw)
To: Desmond Cheong Zhi Xi
Cc: maarten.lankhorst, mripard, tzimmermann, airlied, daniel, peterz,
mingo, will, longman, boqun.feng, dri-devel, linux-kernel, skhan,
gregkh, linux-kernel-mentees
On Sat, Jul 31, 2021 at 04:24:56PM +0800, Desmond Cheong Zhi Xi wrote:
> Hi,
>
> Following a discussion on the patch ("drm: use the lookup lock in
> drm_is_current_master") [1], Peter Zijlstra proposed new lockdep_assert
> helpers to make it convenient to compose lockdep checks together.
>
> This series includes the patch that introduces the new lockdep helpers,
> then utilizes these helpers in drm_is_current_master_locked in the
> following patch.
>
> v1 -> v2:
> Patch 2:
> - Updated the kerneldoc on the lock design of drm_file.master to explain
> the use of lockdep_assert(). As suggested by Boqun Feng.
>
> Link: https://lore.kernel.org/lkml/20210722092929.244629-2-desmondcheongzx@gmail.com/ [1]
Can you pls also cc: this to intel-gfx so the local CI there can pick it
up and verify? Just to check we got it all.
-Daniel
>
> Best wishes,
> Desmond
>
> Desmond Cheong Zhi Xi (1):
> drm: add lockdep assert to drm_is_current_master_locked
>
> Peter Zijlstra (1):
> locking/lockdep: Provide lockdep_assert{,_once}() helpers
>
> drivers/gpu/drm/drm_auth.c | 6 +++---
> include/drm/drm_file.h | 4 ++++
> include/linux/lockdep.h | 41 +++++++++++++++++++-------------------
> 3 files changed, 28 insertions(+), 23 deletions(-)
>
> --
> 2.25.1
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2 0/2] locking/lockdep, drm: apply new lockdep assert in drm_auth.c
2021-08-02 8:26 ` [PATCH v2 0/2] locking/lockdep, drm: apply new lockdep assert in drm_auth.c Daniel Vetter
@ 2021-08-02 9:42 ` Peter Zijlstra
2021-08-02 10:44 ` Desmond Cheong Zhi Xi
1 sibling, 0 replies; 7+ messages in thread
From: Peter Zijlstra @ 2021-08-02 9:42 UTC (permalink / raw)
To: Desmond Cheong Zhi Xi, maarten.lankhorst, mripard, tzimmermann,
airlied, mingo, will, longman, boqun.feng, dri-devel,
linux-kernel, skhan, gregkh, linux-kernel-mentees
On Mon, Aug 02, 2021 at 10:26:16AM +0200, Daniel Vetter wrote:
> On Sat, Jul 31, 2021 at 04:24:56PM +0800, Desmond Cheong Zhi Xi wrote:
> > Hi,
> >
> > Following a discussion on the patch ("drm: use the lookup lock in
> > drm_is_current_master") [1], Peter Zijlstra proposed new lockdep_assert
> > helpers to make it convenient to compose lockdep checks together.
> >
> > This series includes the patch that introduces the new lockdep helpers,
> > then utilizes these helpers in drm_is_current_master_locked in the
> > following patch.
> >
> > v1 -> v2:
> > Patch 2:
> > - Updated the kerneldoc on the lock design of drm_file.master to explain
> > the use of lockdep_assert(). As suggested by Boqun Feng.
> >
> > Link: https://lore.kernel.org/lkml/20210722092929.244629-2-desmondcheongzx@gmail.com/ [1]
>
> Can you pls also cc: this to intel-gfx so the local CI there can pick it
> up and verify? Just to check we got it all.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Feel free to take it through the drm tree.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2 1/2] locking/lockdep: Provide lockdep_assert{,_once}() helpers
2021-07-31 8:24 ` [PATCH v2 1/2] locking/lockdep: Provide lockdep_assert{,_once}() helpers Desmond Cheong Zhi Xi
@ 2021-08-02 9:49 ` Maarten Lankhorst
0 siblings, 0 replies; 7+ messages in thread
From: Maarten Lankhorst @ 2021-08-02 9:49 UTC (permalink / raw)
To: Desmond Cheong Zhi Xi, mripard, tzimmermann, airlied, daniel,
peterz, mingo, will, longman, boqun.feng
Cc: dri-devel, linux-kernel, skhan, gregkh, linux-kernel-mentees
Op 31-07-2021 om 10:24 schreef Desmond Cheong Zhi Xi:
> From: Peter Zijlstra <peterz@infradead.org>
>
> Extract lockdep_assert{,_once}() helpers to more easily write composite
> assertions like, for example:
>
> lockdep_assert(lockdep_is_held(&drm_device.master_mutex) ||
> lockdep_is_held(&drm_file.master_lookup_lock));
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> Signed-off-by: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>
> Acked-by: Boqun Feng <boqun.feng@gmail.com>
> Acked-by: Waiman Long <longman@redhat.com>
> ---
> include/linux/lockdep.h | 41 +++++++++++++++++++++--------------------
> 1 file changed, 21 insertions(+), 20 deletions(-)
>
> diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
> index 5cf387813754..9fe165beb0f9 100644
> --- a/include/linux/lockdep.h
> +++ b/include/linux/lockdep.h
> @@ -306,31 +306,29 @@ extern void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie);
>
> #define lockdep_depth(tsk) (debug_locks ? (tsk)->lockdep_depth : 0)
>
> -#define lockdep_assert_held(l) do { \
> - WARN_ON(debug_locks && \
> - lockdep_is_held(l) == LOCK_STATE_NOT_HELD); \
> - } while (0)
> +#define lockdep_assert(cond) \
> + do { WARN_ON(debug_locks && !(cond)); } while (0)
>
> -#define lockdep_assert_not_held(l) do { \
> - WARN_ON(debug_locks && \
> - lockdep_is_held(l) == LOCK_STATE_HELD); \
> - } while (0)
> +#define lockdep_assert_once(cond) \
> + do { WARN_ON_ONCE(debug_locks && !(cond)); } while (0)
>
> -#define lockdep_assert_held_write(l) do { \
> - WARN_ON(debug_locks && !lockdep_is_held_type(l, 0)); \
> - } while (0)
> +#define lockdep_assert_held(l) \
> + lockdep_assert(lockdep_is_held(l) != LOCK_STATE_NOT_HELD)
>
> -#define lockdep_assert_held_read(l) do { \
> - WARN_ON(debug_locks && !lockdep_is_held_type(l, 1)); \
> - } while (0)
> +#define lockdep_assert_not_held(l) \
> + lockdep_assert(lockdep_is_held(l) != LOCK_STATE_HELD)
>
> -#define lockdep_assert_held_once(l) do { \
> - WARN_ON_ONCE(debug_locks && !lockdep_is_held(l)); \
> - } while (0)
> +#define lockdep_assert_held_write(l) \
> + lockdep_assert(lockdep_is_held_type(l, 0))
>
> -#define lockdep_assert_none_held_once() do { \
> - WARN_ON_ONCE(debug_locks && current->lockdep_depth); \
> - } while (0)
> +#define lockdep_assert_held_read(l) \
> + lockdep_assert(lockdep_is_held_type(l, 1))
> +
> +#define lockdep_assert_held_once(l) \
> + lockdep_assert_once(lockdep_is_held(l) != LOCK_STATE_NOT_HELD)
> +
> +#define lockdep_assert_none_held_once() \
> + lockdep_assert_once(!current->lockdep_depth)
>
> #define lockdep_recursing(tsk) ((tsk)->lockdep_recursion)
>
> @@ -407,6 +405,9 @@ extern int lock_is_held(const void *);
> extern int lockdep_is_held(const void *);
> #define lockdep_is_held_type(l, r) (1)
>
> +#define lockdep_assert(c) do { } while (0)
> +#define lockdep_assert_once(c) do { } while (0)
> +
> #define lockdep_assert_held(l) do { (void)(l); } while (0)
> #define lockdep_assert_not_held(l) do { (void)(l); } while (0)
> #define lockdep_assert_held_write(l) do { (void)(l); } while (0)
All other macros seem to do (void)(c); in this case?
Otherwise looks good.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2 0/2] locking/lockdep, drm: apply new lockdep assert in drm_auth.c
2021-08-02 8:26 ` [PATCH v2 0/2] locking/lockdep, drm: apply new lockdep assert in drm_auth.c Daniel Vetter
2021-08-02 9:42 ` Peter Zijlstra
@ 2021-08-02 10:44 ` Desmond Cheong Zhi Xi
1 sibling, 0 replies; 7+ messages in thread
From: Desmond Cheong Zhi Xi @ 2021-08-02 10:44 UTC (permalink / raw)
To: maarten.lankhorst, mripard, tzimmermann, airlied, peterz, mingo,
will, longman, boqun.feng, dri-devel, linux-kernel, skhan,
gregkh, linux-kernel-mentees
On 2/8/21 4:26 pm, Daniel Vetter wrote:
> On Sat, Jul 31, 2021 at 04:24:56PM +0800, Desmond Cheong Zhi Xi wrote:
>> Hi,
>>
>> Following a discussion on the patch ("drm: use the lookup lock in
>> drm_is_current_master") [1], Peter Zijlstra proposed new lockdep_assert
>> helpers to make it convenient to compose lockdep checks together.
>>
>> This series includes the patch that introduces the new lockdep helpers,
>> then utilizes these helpers in drm_is_current_master_locked in the
>> following patch.
>>
>> v1 -> v2:
>> Patch 2:
>> - Updated the kerneldoc on the lock design of drm_file.master to explain
>> the use of lockdep_assert(). As suggested by Boqun Feng.
>>
>> Link: https://lore.kernel.org/lkml/20210722092929.244629-2-desmondcheongzx@gmail.com/ [1]
>
> Can you pls also cc: this to intel-gfx so the local CI there can pick it
> up and verify? Just to check we got it all.
> -Daniel
>
Oops my bad, I missed out the CI for this series. Will resend with the
proper cc.
Best wishes,
Desmond
>
>>
>> Best wishes,
>> Desmond
>>
>> Desmond Cheong Zhi Xi (1):
>> drm: add lockdep assert to drm_is_current_master_locked
>>
>> Peter Zijlstra (1):
>> locking/lockdep: Provide lockdep_assert{,_once}() helpers
>>
>> drivers/gpu/drm/drm_auth.c | 6 +++---
>> include/drm/drm_file.h | 4 ++++
>> include/linux/lockdep.h | 41 +++++++++++++++++++-------------------
>> 3 files changed, 28 insertions(+), 23 deletions(-)
>>
>> --
>> 2.25.1
>>
>
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2021-08-02 10:44 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
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2021-07-31 8:24 [PATCH v2 0/2] locking/lockdep, drm: apply new lockdep assert in drm_auth.c Desmond Cheong Zhi Xi
2021-07-31 8:24 ` [PATCH v2 1/2] locking/lockdep: Provide lockdep_assert{,_once}() helpers Desmond Cheong Zhi Xi
2021-08-02 9:49 ` Maarten Lankhorst
2021-07-31 8:24 ` [PATCH v2 2/2] drm: add lockdep assert to drm_is_current_master_locked Desmond Cheong Zhi Xi
2021-08-02 8:26 ` [PATCH v2 0/2] locking/lockdep, drm: apply new lockdep assert in drm_auth.c Daniel Vetter
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