* [PATCH] Input: Fix a ref counting issue
@ 2020-11-29 8:45 Christophe JAILLET
2020-11-29 19:49 ` Dmitry Torokhov
0 siblings, 1 reply; 3+ messages in thread
From: Christophe JAILLET @ 2020-11-29 8:45 UTC (permalink / raw)
To: dmitry.torokhov, rydberg, tj
Cc: linux-input, linux-kernel, kernel-janitors, Christophe JAILLET
In case of a managed resource, 'devm_input_device_release()' already has a
'input_put_device(dev)' call.
Avoid a double reference decrement by explicitly calling
'input_put_device()' only on non-managed input device.
Fixes: 2be975c6d920 ("Input: introduce managed input devices (add devres support)")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
This patch is completely speculative and compile tested only.
---
drivers/input/input.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/input/input.c b/drivers/input/input.c
index 3cfd2c18eebd..c09c9f020667 100644
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -1920,7 +1920,8 @@ void input_free_device(struct input_dev *dev)
devm_input_device_release,
devm_input_device_match,
dev));
- input_put_device(dev);
+ else
+ input_put_device(dev);
}
}
EXPORT_SYMBOL(input_free_device);
--
2.27.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] Input: Fix a ref counting issue
2020-11-29 8:45 [PATCH] Input: Fix a ref counting issue Christophe JAILLET
@ 2020-11-29 19:49 ` Dmitry Torokhov
2020-11-29 20:14 ` Christophe JAILLET
0 siblings, 1 reply; 3+ messages in thread
From: Dmitry Torokhov @ 2020-11-29 19:49 UTC (permalink / raw)
To: Christophe JAILLET
Cc: rydberg, tj, linux-input, linux-kernel, kernel-janitors
Hi Christophe,
On Sun, Nov 29, 2020 at 09:45:16AM +0100, Christophe JAILLET wrote:
> In case of a managed resource, 'devm_input_device_release()' already has a
> 'input_put_device(dev)' call.
>
> Avoid a double reference decrement by explicitly calling
> 'input_put_device()' only on non-managed input device.
This patch is incorrect, as devres_destroy() that is used in
input_free_device(), unlike devres_releasde(), does not actually call
the "release" function. It simply destroys the devres object, but does
not clear associated resources.
>
> Fixes: 2be975c6d920 ("Input: introduce managed input devices (add devres support)")
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> ---
> This patch is completely speculative and compile tested only.
> ---
> drivers/input/input.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/input/input.c b/drivers/input/input.c
> index 3cfd2c18eebd..c09c9f020667 100644
> --- a/drivers/input/input.c
> +++ b/drivers/input/input.c
> @@ -1920,7 +1920,8 @@ void input_free_device(struct input_dev *dev)
> devm_input_device_release,
> devm_input_device_match,
> dev));
> - input_put_device(dev);
> + else
> + input_put_device(dev);
> }
> }
> EXPORT_SYMBOL(input_free_device);
> --
> 2.27.0
>
Thanks.
--
Dmitry
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] Input: Fix a ref counting issue
2020-11-29 19:49 ` Dmitry Torokhov
@ 2020-11-29 20:14 ` Christophe JAILLET
0 siblings, 0 replies; 3+ messages in thread
From: Christophe JAILLET @ 2020-11-29 20:14 UTC (permalink / raw)
To: Dmitry Torokhov; +Cc: rydberg, tj, linux-input, linux-kernel, kernel-janitors
Le 29/11/2020 à 20:49, Dmitry Torokhov a écrit :
> Hi Christophe,
>
> On Sun, Nov 29, 2020 at 09:45:16AM +0100, Christophe JAILLET wrote:
>> In case of a managed resource, 'devm_input_device_release()' already has a
>> 'input_put_device(dev)' call.
>>
>> Avoid a double reference decrement by explicitly calling
>> 'input_put_device()' only on non-managed input device.
> This patch is incorrect, as devres_destroy() that is used in
> input_free_device(), unlike devres_releasde(), does not actually call
> the "release" function. It simply destroys the devres object, but does
> not clear associated resources.
Crystal clear.
Thanks for the explanation and sorry for the noise.
CJ
>> Fixes: 2be975c6d920 ("Input: introduce managed input devices (add devres support)")
>> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
>> ---
>> This patch is completely speculative and compile tested only.
>> ---
>> drivers/input/input.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/input/input.c b/drivers/input/input.c
>> index 3cfd2c18eebd..c09c9f020667 100644
>> --- a/drivers/input/input.c
>> +++ b/drivers/input/input.c
>> @@ -1920,7 +1920,8 @@ void input_free_device(struct input_dev *dev)
>> devm_input_device_release,
>> devm_input_device_match,
>> dev));
>> - input_put_device(dev);
>> + else
>> + input_put_device(dev);
>> }
>> }
>> EXPORT_SYMBOL(input_free_device);
>> --
>> 2.27.0
>>
> Thanks.
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2020-11-29 8:45 [PATCH] Input: Fix a ref counting issue Christophe JAILLET
2020-11-29 19:49 ` Dmitry Torokhov
2020-11-29 20:14 ` Christophe JAILLET
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