From: Stanimir Varbanov <stanimir.varbanov@linaro.org>
To: Mansur Alisha Shaik <mansur@codeaurora.org>, linux-media@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
vgarodia@codeaurora.org
Subject: Re: [PATCH v2 2/3] venus: core: cancel pending work items in workqueue
Date: Fri, 11 Sep 2020 13:22:10 +0300 [thread overview]
Message-ID: <a96d7cce-2781-e3d6-6238-8fec411511a1@linaro.org> (raw)
In-Reply-To: <1599741856-16239-3-git-send-email-mansur@codeaurora.org>
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
> 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);
>
--
regards,
Stan
next prev parent reply other threads:[~2020-09-11 10:22 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-10 12:44 [PATCH v2 0/3] Venus - Handle race conditions in concurrency Mansur Alisha Shaik
2020-09-10 12:44 ` [PATCH v2 1/3] venus: core: handle race condititon for core ops Mansur Alisha Shaik
2020-09-11 10:10 ` Stanimir Varbanov
2020-09-17 1:51 ` mansur
2020-09-10 12:44 ` [PATCH v2 2/3] venus: core: cancel pending work items in workqueue Mansur Alisha Shaik
2020-09-11 10:22 ` Stanimir Varbanov [this message]
2020-09-17 1:53 ` mansur
2020-09-10 12:44 ` [PATCH v2 3/3] venus: handle use after free for iommu_map/iommu_unmap Mansur Alisha Shaik
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