On 2020-09-11 15:40, Stanimir Varbanov wrote:
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@xxxxxxxxxxxxxx>
Acked-by: Stanimir Varbanov <stanimir.varbanov@xxxxxxxxxx>
---
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);
Tried above suggestion and ran the failed scenario, I didn't see any
issue.
Posted new version
https://lore.kernel.org/patchwork/project/lkml/list/?series=463091
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;
