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SubjectRe: [PATCH v2 2/3] venus: core: cancel pending work items in workqueue
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@codeaurora.org>
>> ---
>> 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);
>>

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