Re: [PATCH v2 2/3] venus: core: cancel pending work items in workqueue

[mansur]

On 2020-09-11 15:52, Stanimir Varbanov wrote:
> Hi,
>
> On 9/10/20 3:44 PM, Mansur Alisha Shaik wrote:
> > In concurrency usecase and reboot scenario we are
> > observing race condition and seeing NULL pointer
> > dereference crash. In shutdown path and system
> > recovery path we are destroying the same mutex
> > hence seeing crash.
> >
> > This case is handled by mutex protection and
> > cancel delayed work items in work queue.
> >
> > Below is the call trace for the crash
> > Call trace:
> >  venus_remove+0xdc/0xec [venus_core]
> >  venus_core_shutdown+0x1c/0x34 [venus_core]
> >  platform_drv_shutdown+0x28/0x34
> >  device_shutdown+0x154/0x1fc
> >  kernel_restart_prepare+0x40/0x4c
> >  kernel_restart+0x1c/0x64
> >
> > Call trace:
> >  mutex_lock+0x34/0x60
> >  venus_hfi_destroy+0x28/0x98 [venus_core]
> >  hfi_destroy+0x1c/0x28 [venus_core]
>
> I queued up [1] and after it this cannot happen anymore because
> hfi_destroy() is not called by venus_sys_error_handler().
>
> So I guess this patch is not needed anymore.
>
> [1] https://www.spinics.net/lists/linux-arm-msm/msg70092.html
Yes, this patch is not needed any more. rebased and posted new version
https://lore.kernel.org/patchwork/project/lkml/list/?series=463091

> >  venus_sys_error_handler+0x60/0x14c [venus_core]
> >  process_one_work+0x210/0x3d0
> >  worker_thread+0x248/0x3f4
> >  kthread+0x11c/0x12c
> >  ret_from_fork+0x10/0x18
> >
> > Signed-off-by: Mansur Alisha Shaik <mansur@xxxxxxxxxxxxxx>
> > ---
> >  drivers/media/platform/qcom/venus/core.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/drivers/media/platform/qcom/venus/core.c 
> > b/drivers/media/platform/qcom/venus/core.c
> > index c5af428..69aa199 100644
> > --- a/drivers/media/platform/qcom/venus/core.c
> > +++ b/drivers/media/platform/qcom/venus/core.c
> > @@ -323,6 +323,8 @@ static int venus_remove(struct platform_device 
> > *pdev)
> >  	struct device *dev = core->dev;
> >  	int ret;
> >
> > +	cancel_delayed_work_sync(&core->work);
> > +
> >  	ret = pm_runtime_get_sync(dev);
> >  	WARN_ON(ret < 0);
> >
> > @@ -340,7 +342,9 @@ static int venus_remove(struct platform_device 
> > *pdev)
> >  	if (pm_ops->core_put)
> >  		pm_ops->core_put(dev);
> >
> > +	mutex_lock(&core->lock);
> >  	hfi_destroy(core);
> > +	mutex_unlock(&core->lock);
> >
> >  	icc_put(core->video_path);
> >  	icc_put(core->cpucfg_path);