We destroy mutex-es too early as they are still taken in
v4l2_fh_exit()->v4l2_event_unsubscribe()->v4l2_ctrl_find().

We should destroy mutex-es right before kfree().  Also
do not vdec_ctrl_deinit() before v4l2_fh_exit().

Fixes: 7472c1c69138 ("[media] media: venus: vdec: add video decoder files")
Suggested-by: Tomasz Figa <tfiga@google.com>
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
---
 drivers/media/platform/qcom/venus/vdec.c | 7 ++++---
 drivers/media/platform/qcom/venus/venc.c | 6 +++---
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/media/platform/qcom/venus/vdec.c b/drivers/media/platform/qcom/venus/vdec.c
index 6252a6b3d4ba..0013c4704f03 100644
--- a/drivers/media/platform/qcom/venus/vdec.c
+++ b/drivers/media/platform/qcom/venus/vdec.c
@@ -1752,13 +1752,14 @@ static int vdec_close(struct file *file)
 	cancel_work_sync(&inst->delayed_process_work);
 	v4l2_m2m_ctx_release(inst->m2m_ctx);
 	v4l2_m2m_release(inst->m2m_dev);
-	vdec_ctrl_deinit(inst);
 	ida_destroy(&inst->dpb_ids);
 	hfi_session_destroy(inst);
-	mutex_destroy(&inst->lock);
-	mutex_destroy(&inst->ctx_q_lock);
 	v4l2_fh_del(&inst->fh);
 	v4l2_fh_exit(&inst->fh);
+	vdec_ctrl_deinit(inst);
+
+	mutex_destroy(&inst->lock);
+	mutex_destroy(&inst->ctx_q_lock);
 
 	vdec_pm_put(inst, false);
 
diff --git a/drivers/media/platform/qcom/venus/venc.c b/drivers/media/platform/qcom/venus/venc.c
index 322a7737e2c7..6a26a6592424 100644
--- a/drivers/media/platform/qcom/venus/venc.c
+++ b/drivers/media/platform/qcom/venus/venc.c
@@ -1519,14 +1519,14 @@ static int venc_close(struct file *file)
 
 	v4l2_m2m_ctx_release(inst->m2m_ctx);
 	v4l2_m2m_release(inst->m2m_dev);
-	venc_ctrl_deinit(inst);
 	hfi_session_destroy(inst);
-	mutex_destroy(&inst->lock);
-	mutex_destroy(&inst->ctx_q_lock);
 	v4l2_fh_del(&inst->fh);
 	v4l2_fh_exit(&inst->fh);
+	venc_ctrl_deinit(inst);
 
 	inst->enc_state = VENUS_ENC_STATE_DEINIT;
+	mutex_destroy(&inst->lock);
+	mutex_destroy(&inst->ctx_q_lock);
 
 	venc_pm_put(inst, false);
 
-- 
2.47.0.163.g1226f6d8fa-goog

On 10/25/2024 9:16 AM, Sergey Senozhatsky wrote:
> We destroy mutex-es too early as they are still taken in
> v4l2_fh_exit()->v4l2_event_unsubscribe()->v4l2_ctrl_find().
> 
> We should destroy mutex-es right before kfree().  Also
> do not vdec_ctrl_deinit() before v4l2_fh_exit().
> 
> Fixes: 7472c1c69138 ("[media] media: venus: vdec: add video decoder files")
> Suggested-by: Tomasz Figa <tfiga@google.com>
> Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
> Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
> ---
>  drivers/media/platform/qcom/venus/vdec.c | 7 ++++---
>  drivers/media/platform/qcom/venus/venc.c | 6 +++---
>  2 files changed, 7 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/media/platform/qcom/venus/vdec.c b/drivers/media/platform/qcom/venus/vdec.c
> index 6252a6b3d4ba..0013c4704f03 100644
> --- a/drivers/media/platform/qcom/venus/vdec.c
> +++ b/drivers/media/platform/qcom/venus/vdec.c
> @@ -1752,13 +1752,14 @@ static int vdec_close(struct file *file)
>  	cancel_work_sync(&inst->delayed_process_work);
>  	v4l2_m2m_ctx_release(inst->m2m_ctx);
>  	v4l2_m2m_release(inst->m2m_dev);
> -	vdec_ctrl_deinit(inst);
>  	ida_destroy(&inst->dpb_ids);
>  	hfi_session_destroy(inst);
> -	mutex_destroy(&inst->lock);
> -	mutex_destroy(&inst->ctx_q_lock);
>  	v4l2_fh_del(&inst->fh);
>  	v4l2_fh_exit(&inst->fh);
> +	vdec_ctrl_deinit(inst);
Why vdec_ctrl_deinit ->v4l2_ctrl_handler_free(&inst->ctrl_handler) needs to
be called after v4l2_fh_exit?
Ideally it should be before v4l2_fh_exit.

Thanks,
Dikshita
> +
> +	mutex_destroy(&inst->lock);
> +	mutex_destroy(&inst->ctx_q_lock);
>  
>  	vdec_pm_put(inst, false);
>  
> diff --git a/drivers/media/platform/qcom/venus/venc.c b/drivers/media/platform/qcom/venus/venc.c
> index 322a7737e2c7..6a26a6592424 100644
> --- a/drivers/media/platform/qcom/venus/venc.c
> +++ b/drivers/media/platform/qcom/venus/venc.c
> @@ -1519,14 +1519,14 @@ static int venc_close(struct file *file)
>  
>  	v4l2_m2m_ctx_release(inst->m2m_ctx);
>  	v4l2_m2m_release(inst->m2m_dev);
> -	venc_ctrl_deinit(inst);
>  	hfi_session_destroy(inst);
> -	mutex_destroy(&inst->lock);
> -	mutex_destroy(&inst->ctx_q_lock);
>  	v4l2_fh_del(&inst->fh);
>  	v4l2_fh_exit(&inst->fh);
> +	venc_ctrl_deinit(inst);
>  
>  	inst->enc_state = VENUS_ENC_STATE_DEINIT;
> +	mutex_destroy(&inst->lock);
> +	mutex_destroy(&inst->ctx_q_lock);
>  
>  	venc_pm_put(inst, false);
>

On (24/10/25 12:50), Dikshita Agarwal wrote:
> > diff --git a/drivers/media/platform/qcom/venus/vdec.c b/drivers/media/platform/qcom/venus/vdec.c
> > index 6252a6b3d4ba..0013c4704f03 100644
> > --- a/drivers/media/platform/qcom/venus/vdec.c
> > +++ b/drivers/media/platform/qcom/venus/vdec.c
> > @@ -1752,13 +1752,14 @@ static int vdec_close(struct file *file)
> >  	cancel_work_sync(&inst->delayed_process_work);
> >  	v4l2_m2m_ctx_release(inst->m2m_ctx);
> >  	v4l2_m2m_release(inst->m2m_dev);
> > -	vdec_ctrl_deinit(inst);
> >  	ida_destroy(&inst->dpb_ids);
> >  	hfi_session_destroy(inst);
> > -	mutex_destroy(&inst->lock);
> > -	mutex_destroy(&inst->ctx_q_lock);
> >  	v4l2_fh_del(&inst->fh);
> >  	v4l2_fh_exit(&inst->fh);
> > +	vdec_ctrl_deinit(inst);
> Why vdec_ctrl_deinit ->v4l2_ctrl_handler_free(&inst->ctrl_handler) needs to
> be called after v4l2_fh_exit?
> Ideally it should be before v4l2_fh_exit.

Because ->fh holds a pointer to ->ctrl_handler

	inst->fh.ctrl_handler = &inst->ctrl_handler

so after vdec_ctrl_deinit() fh holds stale (released) data.
In general destruction in reverse order of initialization is
safer.

init:
	init ctrl
	init fh     // using ctrl

de-init:
	release fh
	release ctrl