2020-09-16 08:52:51

by Mansur Alisha Shaik

[permalink] [raw]
Subject: [PATCH v4 0/3] venus: core: add shutdown callback for venus

Add shutdown callback for venus driver.
Handle race conditions in concurrency usecases like
multiple browser YouTube browser tabs(approx 50 tabs)
graphics_Stress, WiFi ON/OFF, Bluetooth ON/OF,
and reboot in parallel.

Mansur Alisha Shaik (3):
venus: core: handle race condititon for core ops
venus: handle use after free for iommu_map/iommu_unmap
venus: core: add shutdown callback for venus

drivers/media/platform/qcom/venus/core.c | 9 +++++++++
drivers/media/platform/qcom/venus/firmware.c | 17 +++++++++++++----
drivers/media/platform/qcom/venus/hfi.c | 17 ++++++++++++++++-
3 files changed, 38 insertions(+), 5 deletions(-)

--
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation


2020-09-16 08:54:06

by Mansur Alisha Shaik

[permalink] [raw]
Subject: [PATCH v4 1/3] venus: core: handle race condititon for core ops

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 <[email protected]>
Acked-by: Stanimir Varbanov <[email protected]>
---
Changes in V4:
- Addressed review comments by Stan in patch series
https://lore.kernel.org/patchwork/patch/1303678/
and combining this change along with shutdown callback
as we are facing race conditions with shutdown callback

drivers/media/platform/qcom/venus/hfi.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/media/platform/qcom/venus/hfi.c b/drivers/media/platform/qcom/venus/hfi.c
index a59022a..58d4c06 100644
--- a/drivers/media/platform/qcom/venus/hfi.c
+++ b/drivers/media/platform/qcom/venus/hfi.c
@@ -195,19 +195,34 @@ 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 core shutdown is in progress or if we are in system
+ * recovery, return an error as during system error recovery
+ * session_init() can't pass successfully
+ */
+ mutex_lock(&core->lock);
+ if (!core->ops || core->sys_error) {
+ mutex_unlock(&core->lock);
+ return -EIO;
+ }
+ mutex_unlock(&core->lock);
+
if (inst->state != INST_UNINIT)
return -EINVAL;

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;
--
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation

2020-09-20 21:18:37

by Stanimir Varbanov

[permalink] [raw]
Subject: Re: [PATCH v4 1/3] venus: core: handle race condititon for core ops



On 9/16/20 11:49 AM, 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 <[email protected]>
> Acked-by: Stanimir Varbanov <[email protected]>
> ---
> Changes in V4:
> - Addressed review comments by Stan in patch series
> https://lore.kernel.org/patchwork/patch/1303678/
> and combining this change along with shutdown callback
> as we are facing race conditions with shutdown callback
>
> drivers/media/platform/qcom/venus/hfi.c | 17 ++++++++++++++++-
> 1 file changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/platform/qcom/venus/hfi.c b/drivers/media/platform/qcom/venus/hfi.c
> index a59022a..58d4c06 100644
> --- a/drivers/media/platform/qcom/venus/hfi.c
> +++ b/drivers/media/platform/qcom/venus/hfi.c
> @@ -195,19 +195,34 @@ 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 core shutdown is in progress or if we are in system
> + * recovery, return an error as during system error recovery
> + * session_init() can't pass successfully
> + */
> + mutex_lock(&core->lock);
> + if (!core->ops || core->sys_error) {
> + mutex_unlock(&core->lock);
> + return -EIO;
> + }
> + mutex_unlock(&core->lock);
> +
> if (inst->state != INST_UNINIT)
> return -EINVAL;
>
> inst->hfi_codec = to_codec_type(pixfmt);
> reinit_completion(&inst->done);
>
> + mutex_lock(&core->lock);
> + ops = core->ops;

This is not needed because we check core->ops for NULL under mutex held
at the beginning of the function. Just keep ops initialization as it is
in the original code.

> 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