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 1/3] venus: core: handle race condititon for core ops
Date: Fri, 11 Sep 2020 13:10:57 +0300 [thread overview]
Message-ID: <313cf565-f69f-df84-6bff-8c9a77b9f642@linaro.org> (raw)
In-Reply-To: <1599741856-16239-2-git-send-email-mansur@codeaurora.org>
On 9/10/20 3:44 PM, Mansur Alisha Shaik wrote:
> For core ops we are having only write protect but there
> is no read protect, because of this in multthreading
> and concurrency, one CPU core is reading without wait
> which is causing the NULL pointer dereferece crash.
>
> one such scenario is as show below, where in one CPU
> core, core->ops becoming NULL and in another CPU core
> calling core->ops->session_init().
>
> CPU: core-7:
> Call trace:
> hfi_session_init+0x180/0x1dc [venus_core]
> vdec_queue_setup+0x9c/0x364 [venus_dec]
> vb2_core_reqbufs+0x1e4/0x368 [videobuf2_common]
> vb2_reqbufs+0x4c/0x64 [videobuf2_v4l2]
> v4l2_m2m_reqbufs+0x50/0x84 [v4l2_mem2mem]
> v4l2_m2m_ioctl_reqbufs+0x2c/0x38 [v4l2_mem2mem]
> v4l_reqbufs+0x4c/0x5c
> __video_do_ioctl+0x2b0/0x39c
>
> CPU: core-0:
> Call trace:
> venus_shutdown+0x98/0xfc [venus_core]
> venus_sys_error_handler+0x64/0x148 [venus_core]
> process_one_work+0x210/0x3d0
> worker_thread+0x248/0x3f4
> kthread+0x11c/0x12c
>
> Signed-off-by: Mansur Alisha Shaik <mansur@codeaurora.org>
> Acked-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
> ---
> Changes in V2:
> - Addressed review comments by stan by validating on top
> - of https://lore.kernel.org/patchwork/project/lkml/list/?series=455962
>
> drivers/media/platform/qcom/venus/hfi.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/platform/qcom/venus/hfi.c b/drivers/media/platform/qcom/venus/hfi.c
> index a59022a..3137071 100644
> --- a/drivers/media/platform/qcom/venus/hfi.c
> +++ b/drivers/media/platform/qcom/venus/hfi.c
> @@ -195,7 +195,7 @@ EXPORT_SYMBOL_GPL(hfi_session_create);
> int hfi_session_init(struct venus_inst *inst, u32 pixfmt)
> {
> struct venus_core *core = inst->core;
> - const struct hfi_ops *ops = core->ops;
> + const struct hfi_ops *ops;
> int ret;
>
If we are in system error recovery the session_init cannot pass
successfully, so we exit early in the function.
I'd suggest to make it:
/* If core shutdown is in progress or we are in system error recovery,
return an error */
mutex_lock(&core->lock);
if (!core->ops || core->sys_error) {
mutex_unclock(&core->lock);
return -EIO;
}
mutex_unclock(&core->lock);
> if (inst->state != INST_UNINIT)
> @@ -204,10 +204,13 @@ int hfi_session_init(struct venus_inst *inst, u32 pixfmt)
> inst->hfi_codec = to_codec_type(pixfmt);
> reinit_completion(&inst->done);
>
> + mutex_lock(&core->lock);
> + ops = core->ops;
> ret = ops->session_init(inst, inst->session_type, inst->hfi_codec);
> if (ret)
> return ret;
>
> + mutex_unlock(&core->lock);
> ret = wait_session_msg(inst);
> if (ret)
> return ret;
>
--
regards,
Stan
next prev parent reply other threads:[~2020-09-11 10:11 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 [this message]
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
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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