Re: [PATCH] PM / devfreq: try_then_request_governor should not return NULL

From: Chanwoo Choi
Date: Fri May 24 2019 - 03:16:35 EST


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. ìì 6:58, Rob Clark wrote:
> From: Rob Clark <robdclark@xxxxxxxxxxxx>
>
> 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@xxxxxxxxxxxx>
> ---
> 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