Re: [PATCHv3 1/3] media: venus: fix enc/dec destruction order

[Sergey Senozhatsky <senozhatsky@chromium.org>]

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