Re: [PATCH v2] s5p-mfc: Don't try to put pm->clock if lookup failed

[Javier Martinez Canillas]

Hello Krzysztof,

On 05/03/2016 06:15 AM, Krzysztof Kozlowski wrote:
> On Mon, May 02, 2016 at 03:14:22PM -0400, Javier Martinez Canillas wrote:
>> Failing to get the struct s5p_mfc_pm .clock is a non-fatal error so the
>> clock field can have a errno pointer value. But s5p_mfc_final_pm() only
>> checks if .clock is not NULL before attempting to unprepare and put it.
>>
>> This leads to the following warning in clk_put() due s5p_mfc_final_pm():
>>
>> WARNING: CPU: 3 PID: 1023 at drivers/clk/clk.c:2814 s5p_mfc_final_pm+0x48/0x74 [s5p_mfc]
>> CPU: 3 PID: 1023 Comm: rmmod Tainted: G        W       4.6.0-rc6-next-20160502-00005-g5a15a49106bc #9
>> Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
>> [<c010e1bc>] (unwind_backtrace) from [<c010af28>] (show_stack+0x10/0x14)
>> [<c010af28>] (show_stack) from [<c032485c>] (dump_stack+0x88/0x9c)
>> [<c032485c>] (dump_stack) from [<c011b8e8>] (__warn+0xe8/0x100)
>> [<c011b8e8>] (__warn) from [<c011b9b0>] (warn_slowpath_null+0x20/0x28)
>> [<c011b9b0>] (warn_slowpath_null) from [<bf16004c>] (s5p_mfc_final_pm+0x48/0x74 [s5p_mfc])
>> [<bf16004c>] (s5p_mfc_final_pm [s5p_mfc]) from [<bf157414>] (s5p_mfc_remove+0x8c/0x94 [s5p_mfc])
>> [<bf157414>] (s5p_mfc_remove [s5p_mfc]) from [<c03fe1f8>] (platform_drv_remove+0x24/0x3c)
>> [<c03fe1f8>] (platform_drv_remove) from [<c03fcc70>] (__device_release_driver+0x84/0x110)
>> [<c03fcc70>] (__device_release_driver) from [<c03fcdd8>] (driver_detach+0xac/0xb0)
>> [<c03fcdd8>] (driver_detach) from [<c03fbff8>] (bus_remove_driver+0x4c/0xa0)
>> [<c03fbff8>] (bus_remove_driver) from [<c01886a8>] (SyS_delete_module+0x174/0x1b8)
>> [<c01886a8>] (SyS_delete_module) from [<c01078c0>] (ret_fast_syscall+0x0/0x3c)
>>
>> Assign the pointer to NULL in case of a lookup failure to fix the issue.
>>
>> Signed-off-by: Javier Martinez Canillas <javier@xxxxxxxxxxxxxxx>
>>
>> ---
>>
>> Changes in v2:
>> - Set the clock pointer to NULL instead of checking for !IS_ERR_OR_NULL().
>>   Suggested by Arnd Bergmann.
>>
>>  drivers/media/platform/s5p-mfc/s5p_mfc_pm.c | 1 +
>>  1 file changed, 1 insertion(+)
> 
> This is a fix for bug, so for statistics:
> Fixes: d19f405a5a8d ("[media] s5p-mfc: Fix selective sclk_mfc init")
> 
> ... and although not fatal, but annoying so I think this deserves:
> Cc: <stable@xxxxxxxxxxxxxxx>
>

Indeed, sorry for missing those.
 
> Anyway:
> Reviewed-by: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx>
>

Thanks a lot for your feedback.
 
> Best regards,
> Krzysztof
> 

Best regards,
-- 
Javier Martinez Canillas
Open Source Group
Samsung Research America