Re: [PATCH 1/2] firmware, fix request_firmware_nowait() freeze with no uevent

[Ming Lei <ming.lei@canonical.com>]

On Mon, Oct 21, 2013 at 5:35 AM, Prarit Bhargava <prarit@redhat.com> wrote:
> If request_firmware_nowait() is called with uevent == NULL, the firmware
> completion is never marked complete resulting in a hang in the process.
>
> If uevent is undefined, that means we're not waiting on anything and the
> process should just clean up and complete.  While we're at it, add a
> debug dev_dbg() to indicate that the FW has not been found.
>
> Signed-off-by: Prarit Bhargava <prarit@redhat.com>
> Cc: x86@kernel.org
> Cc: herrmann.der.user@googlemail.com
> Cc: ming.lei@canonical.com
> Cc: tigran@aivazian.fsnet.co.uk
> ---
>  drivers/base/firmware_class.c |    6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
> index 10a4467..95778dc 100644
> --- a/drivers/base/firmware_class.c
> +++ b/drivers/base/firmware_class.c
> @@ -335,7 +335,8 @@ static bool fw_get_filesystem_firmware(struct device *device,
>                 set_bit(FW_STATUS_DONE, &buf->status);
>                 complete_all(&buf->completion);
>                 mutex_unlock(&fw_lock);
> -       }
> +       } else
> +               dev_dbg(device, "firmware: %s not found\n", buf->fw_id);
>
>         return success;
>  }
> @@ -886,6 +887,9 @@ static int _request_firmware_load(struct firmware_priv *fw_priv, bool uevent,
>                         schedule_delayed_work(&fw_priv->timeout_work, timeout);
>
>                 kobject_uevent(&fw_priv->dev.kobj, KOBJ_ADD);
> +       } else {
> +               /* if there is no uevent then just cleanup */
> +               schedule_delayed_work(&fw_priv->timeout_work, 0);
>         }

This may not a good idea and might break current NOHOTPLUG
users, and how can you make sure the user space application can
complete the request during the timeout time?

Thanks,
--
Ming Lei