Re: [PATCH v3 2/2] firmware: qcom: scm: Allow the SMC request to freeze

[Pavan Kondeti]

On Thu, Oct 01, 2026 at 06:16:49PM +0200, Albert Esteve wrote:
> From: Yuvaraj Ranganathan <yrangana@xxxxxxxxxxxxxxxx>
> 
> qcom_scm_wait_for_wq_completion() waits in TASK_IDLE. That is
> uninterruptible, so a thread parked on a firmware waitq cannot be
> frozen or killed. A long wait then blocks suspend, and shutdown
> cannot tear the task down.
> 
> Wait with TASK_IDLE | TASK_FREEZABLE so the freezer can freeze the
> waiter during suspend; after resume it is still waiting
> for the same waitq completion.
> 
> TASK_KILLABLE is not added. If a fatal signal aborts the wait, the
> driver returns early without issuing QCOM_SCM_WAITQ_RESUME, leaking
> the TrustZone execution context.
> 
> Fixes: 366f05e348b2 ("firmware: qcom_scm: Use TASK_IDLE state in wait_for_wq_completion()")
> Signed-off-by: Yuvaraj Ranganathan <yrangana@xxxxxxxxxxxxxxxx>
> Signed-off-by: Albert Esteve <aesteve@xxxxxxxxxx>
> ---
>  drivers/firmware/qcom/qcom_scm.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
> index ea4481385412..92cee2263ed4 100644
> --- a/drivers/firmware/qcom/qcom_scm.c
> +++ b/drivers/firmware/qcom/qcom_scm.c
> @@ -2664,9 +2664,7 @@ int qcom_scm_wait_for_wq_completion(struct device *dev, u32 wq_ctx)
>  	if (IS_ERR(wq))
>  		return PTR_ERR(wq);
>  
> -	wait_for_completion_state(wq, TASK_IDLE);
> -
> -	return 0;
> +	return wait_for_completion_state(wq, TASK_IDLE | TASK_FREEZABLE);
>  }
>  
If the wakeup happens while the task is frozen, the task will come out
of completion only when the task is thawed. I don't know if there are
any cases where that is not acceptable now that we are making all
non-atomic calls to enter w/o mutex.

Thanks,
Pavan