linux-kernel - Re: [PATCH] PM / devfreq: try_then_request

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Message-ID: <e1232f97-c80d-2bf2-639a-7f7b9195d1f0@samsung.com>
Date:   Tue, 28 May 2019 10:18:06 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Rob Clark <robdclark@...omium.org>
Cc:     Rob Clark <robdclark@...il.com>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        linux-pm@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] PM / devfreq: try_then_request_governor should not
 return NULL

Hi Rob,

You're right. It have to be posted to stable@...r.kernel.org.
As you recommended, I send it[1] to stable@...r.kernel.org for fixup.
[1]https://lkml.org/lkml/2019/5/27/547

Best Regards,
Chanwoo Choi

On 19. 5. 24. 오후 10:15, Rob Clark wrote:
> Ahh, thanks, I've not moved to the latest -rc yet..
> 
> That commit would be a good candidate for 5.1.y stable branch
> 
> BR,
> -R
> 
> On Fri, May 24, 2019 at 12:13 AM Chanwoo Choi <cw00.choi@...sung.com> wrote:
>>
>> Hi,
>>
>> This issue[1] is already fixed on latest linux.git
>> You can check it. Thanks.
>>
>> [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b53b0128052ffd687797d5f4deeb76327e7b5711
>>
>> Regards,
>> Chanwoo Choi
>>
>>
>> On 19. 5. 24. 오전 6:58, Rob Clark wrote:
>>> From: Rob Clark <robdclark@...omium.org>
>>>
>>> The two spots it is called expect either an IS_ERR() or a valid pointer,
>>> but not NULL.
>>>
>>> Fixes this crash that I came across:
>>>
>>>    Unable to handle kernel NULL pointer dereference at virtual address 0000000000000030
>>>    Mem abort info:
>>>      ESR = 0x96000005
>>>      Exception class = DABT (current EL), IL = 32 bits
>>>      SET = 0, FnV = 0
>>>      EA = 0, S1PTW = 0
>>>    Data abort info:
>>>      ISV = 0, ISS = 0x00000005
>>>      CM = 0, WnR = 0
>>>    [0000000000000030] user address but active_mm is swapper
>>>    Internal error: Oops: 96000005 [#1] PREEMPT SMP
>>>    Modules linked in:
>>>    Process kworker/2:1 (pid: 212, stack limit = 0x(____ptrval____))
>>>    CPU: 2 PID: 212 Comm: kworker/2:1 Not tainted 5.1.0-43338-g460e6984675c-dirty #54
>>>    Hardware name: Google Cheza (rev3+) (DT)
>>>    Workqueue: events deferred_probe_work_func
>>>    pstate: 00c00009 (nzcv daif +PAN +UAO)
>>>    pc : devfreq_add_device+0x2e4/0x410
>>>    lr : devfreq_add_device+0x2d4/0x410
>>>    sp : ffffff8013d93740
>>>    x29: ffffff8013d93790 x28: ffffffc0f54f8670
>>>    x27: 0000000000000001 x26: 0000000000000007
>>>    x25: ffffff80124abfd8 x24: 0000000000000000
>>>    x23: ffffffc0fabc4048 x22: ffffffc0fabc4388
>>>    x21: ffffffc0fabc4010 x20: ffffffc0fa243010
>>>    x19: ffffffc0fabc4000 x18: 0000000091c3d373
>>>    x17: 0000000000000400 x16: 000000000000001a
>>>    x15: 000000019e06d400 x14: 0000000000000001
>>>    x13: 0000000000000000 x12: 00000000000006b6
>>>    x11: 0000000000000000 x10: 0000000000000000
>>>    x9 : ffffffc0fa18ba00 x8 : 0000000000000000
>>>    x7 : 0000000000000000 x6 : ffffff80127a3d9a
>>>    x5 : ffffff8013d93550 x4 : 0000000000000000
>>>    x3 : 0000000000000000 x2 : 0000000000000000
>>>    x1 : 00000000000000fe x0 : 0000000000000000
>>>    Call trace:
>>>     devfreq_add_device+0x2e4/0x410
>>>     devm_devfreq_add_device+0x64/0xac
>>>     msm_gpu_init+0x320/0x5c0
>>>     adreno_gpu_init+0x21c/0x274
>>>     a6xx_gpu_init+0x68/0xf4
>>>     adreno_bind+0x158/0x284
>>>     component_bind_all+0x110/0x204
>>>     msm_drm_bind+0x118/0x5b8
>>>     try_to_bring_up_master+0x15c/0x19c
>>>     component_master_add_with_match+0xb4/0xec
>>>     msm_pdev_probe+0x1f0/0x27c
>>>     platform_drv_probe+0x90/0xb0
>>>     really_probe+0x120/0x298
>>>     driver_probe_device+0x64/0xfc
>>>     __device_attach_driver+0x8c/0xa4
>>>     bus_for_each_drv+0x88/0xd0
>>>     __device_attach+0xac/0x134
>>>     device_initial_probe+0x20/0x2c
>>>     bus_probe_device+0x34/0x90
>>>     deferred_probe_work_func+0x74/0xac
>>>     process_one_work+0x210/0x428
>>>     worker_thread+0x278/0x3e4
>>>     kthread+0x120/0x130
>>>     ret_from_fork+0x10/0x18
>>>    Code: aa0003f8 b13ffc1f 54000762 f901c278 (f9401b08)
>>>    ---[ end trace a6ecc18ce5894375 ]---
>>>    Kernel panic - not syncing: Fatal exception
>>>
>>> Signed-off-by: Rob Clark <robdclark@...omium.org>
>>> ---
>>>  drivers/devfreq/devfreq.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>>> index 0ae3de76833b..d29f66f0e52a 100644
>>> --- a/drivers/devfreq/devfreq.c
>>> +++ b/drivers/devfreq/devfreq.c
>>> @@ -254,7 +254,7 @@ static struct devfreq_governor *try_then_request_governor(const char *name)
>>>               /* Restore previous state before return */
>>>               mutex_lock(&devfreq_list_lock);
>>>               if (err)
>>> -                     return NULL;
>>> +                     return ERR_PTR(err);
>>>
>>>               governor = find_devfreq_governor(name);
>>>       }
>>>
>>
>>
>> --
>> Best Regards,
>> Chanwoo Choi
>> Samsung Electronics
> 
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics