[PATCH v5] workqueue: Remove unnecessary kfree() call in rcu_free_wq()

[PATCH v5] workqueue: Remove unnecessary kfree() call in rcu_free_wq()

[qiang.zhang]

From: Zhang Qiang <qiang.zhang@windriver.com>

The data structure member "wq->rescuer" was reset to a null pointer
in one if branch. It was passed to a call of the function "kfree"
in the callback function "rcu_free_wq" (which was eventually executed).
The function "kfree" does not perform more meaningful data processing
for a passed null pointer (besides immediately returning from such a call).
Thus delete this function call which became unnecessary with the referenced
software update.

Fixes: def98c84b6cd ("workqueue: Fix spurious sanity check failures in destroy_workqueue()")

Co-developed-by: Markus Elfring <Markus.Elfring@web.de> 
Signed-off-by: Zhang Qiang <qiang.zhang@windriver.com>
---
 v1->v2->v3->v4->v5:
 Modify weakly submitted information.

 kernel/workqueue.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 891ccad5f271..a2451cdcd503 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -3491,7 +3491,6 @@ static void rcu_free_wq(struct rcu_head *rcu)
 	else
 		free_workqueue_attrs(wq->unbound_attrs);
 
-	kfree(wq->rescuer);
 	kfree(wq);
 }
 
-- 
2.24.1

Re: [PATCH v5] workqueue: Remove unnecessary kfree() call in rcu_free_wq()

[Tejun Heo]

On Wed, May 27, 2020 at 03:57:15PM +0800, qiang.zhang@windriver.com wrote:
> From: Zhang Qiang <qiang.zhang@windriver.com>
> 
> The data structure member "wq->rescuer" was reset to a null pointer
> in one if branch. It was passed to a call of the function "kfree"
> in the callback function "rcu_free_wq" (which was eventually executed).
> The function "kfree" does not perform more meaningful data processing
> for a passed null pointer (besides immediately returning from such a call).
> Thus delete this function call which became unnecessary with the referenced
> software update.
> 
> Fixes: def98c84b6cd ("workqueue: Fix spurious sanity check failures in destroy_workqueue()")
> 
> Suggested-by: Markus Elfring <Markus.Elfring@web.de> 
> Signed-off-by: Zhang Qiang <qiang.zhang@windriver.com>

Applied to wq/for-5.8.

Thanks.

-- 
tejun

Re: [PATCH v5] workqueue: Remove unnecessary kfree() call in rcu_free_wq()

[Markus Elfring]

> Thus delete this function call which became unnecessary with the referenced
> software update.
…
> Suggested-by: Markus Elfring <Markus.Elfring@web.de>

Would the tag “Co-developed-by” be more appropriate according to the patch review
to achieve a more pleasing commit message?


>  v1->v2->v3->v4->v5:
>  Modify weakly submitted information.

Now I wonder about your wording choice “weakly”.

Regards,
Markus

Re: [PATCH v5] workqueue: Remove unnecessary kfree() call in rcu_free_wq()

[Markus Elfring]

> Thus delete this function call which became unnecessary with the referenced
> software update.
…
> Suggested-by: Markus Elfring <Markus.Elfring@web.de>

Would the tag “Co-developed-by” be more appropriate according to the patch review
to achieve a more pleasing commit message?


>  v1->v2->v3->v4->v5:
>  Modify weakly submitted information.

Now I wonder about your wording choice “weakly”.

Regards,
Markus

[PATCH v5] workqueue: Remove unnecessary kfree() call in rcu_free_wq()

[qiang.zhang]

From: Zhang Qiang <qiang.zhang@windriver.com>

The data structure member "wq->rescuer" was reset to a null pointer
in one if branch. It was passed to a call of the function "kfree"
in the callback function "rcu_free_wq" (which was eventually executed).
The function "kfree" does not perform more meaningful data processing
for a passed null pointer (besides immediately returning from such a call).
Thus delete this function call which became unnecessary with the referenced
software update.

Fixes: def98c84b6cd ("workqueue: Fix spurious sanity check failures in destroy_workqueue()")

Suggested-by: Markus Elfring <Markus.Elfring@web.de> 
Signed-off-by: Zhang Qiang <qiang.zhang@windriver.com>
---
 v1->v2->v3->v4->v5:
 Modify weakly submitted information.

 kernel/workqueue.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 891ccad5f271..a2451cdcd503 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -3491,7 +3491,6 @@ static void rcu_free_wq(struct rcu_head *rcu)
 	else
 		free_workqueue_attrs(wq->unbound_attrs);
 
-	kfree(wq->rescuer);
 	kfree(wq);
 }
 
-- 
2.24.1