Re: [PATCH 1/2] remoteproc: core: Attach rproc asynchronously in rproc_add() path

[Stephan Gerhold <stephan.gerhold@linaro.org>]

+Cc Bartosz, Dmitry

On Thu, Apr 09, 2026 at 01:46:21AM -0700, Jingyi Wang wrote:
> For rproc with state RPROC_DETACHED and auto_boot enabled, the attach
> callback will be called in the rproc_add()->rproc_trigger_auto_boot()->
> rproc_boot() path, the failure in this path will cause the rproc_add()
> fail and the resource release, which will cause issue like rproc recovery
> or falling back to firmware load fail. Add attach_work for rproc and call
> it asynchronously in rproc_add() path like what rproc_start() do.
> 
> Signed-off-by: Jingyi Wang <jingyi.wang@oss.qualcomm.com>
> ---
>  drivers/remoteproc/remoteproc_core.c | 20 ++++++++++++--------
>  include/linux/remoteproc.h           |  1 +
>  2 files changed, 13 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index b087ed21858a..f02db1113fae 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -1673,18 +1673,21 @@ static void rproc_auto_boot_callback(const struct firmware *fw, void *context)
>  	release_firmware(fw);
>  }
>  
> +static void rproc_attach_work(struct work_struct *work)
> +{
> +	struct rproc *rproc = container_of(work, struct rproc, attach_work);
> +
> +	rproc_boot(rproc);
> +}
> +
>  static int rproc_trigger_auto_boot(struct rproc *rproc)
>  {
>  	int ret;
>  
> -	/*
> -	 * Since the remote processor is in a detached state, it has already
> -	 * been booted by another entity.  As such there is no point in waiting
> -	 * for a firmware image to be loaded, we can simply initiate the process
> -	 * of attaching to it immediately.
> -	 */
> -	if (rproc->state == RPROC_DETACHED)
> -		return rproc_boot(rproc);
> +	if (rproc->state == RPROC_DETACHED) {
> +		schedule_work(&rproc->attach_work);
> +		return 0;
> +	}

I think the change itself is reasonable to make "auto-attach" behavior
consistent with "auto-boot". The commit message is a bit misleading
though:

 - You're really doing two separate functional changes here:

   (1) Ignore the return value of rproc_boot() during auto-boot attach,
       to keep the remoteproc registered and available in sysfs even if
       attaching fails.
   (2) Run the rproc_boot() in the background using schedule_work().
       [To improve boot performance? To work around some locking issues?]

 - The actual issue you are seeing sounds like a use-after-free in the
   remoteproc core error cleanup path. I think this one is still
   present, we should really have a call to
   cancel_work_sync(&rproc->crash_handler) as Dmitry wrote in the
   previous discussion [1].

Thanks,
Stephan

[1]: https://lore.kernel.org/all/ce24a2sgg4b6wymoxwgl2ve6np2nxn2wuxfqxfpmvqqrpvgouf@xihd6ziqwu4m/