linux-kernel - Re: [PATCH] f_midi_complete to call tasklet_hi

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Message-ID: <2025020708-manned-antidote-7d57@gregkh>
Date: Fri, 7 Feb 2025 10:35:16 +0100
From: Greg KH <gregkh@...uxfoundation.org>
To: Jillian Donahue <jilliandonahue58@...il.com>
Cc: linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org
Subject: Re: [PATCH] f_midi_complete to call tasklet_hi_schedule

On Thu, Feb 06, 2025 at 12:32:14PM -0700, Jillian Donahue wrote:
> >From 9cb2628740d9f55f6f3faa5cce2de5eb8590f434 Mon Sep 17 00:00:00 2001
> From: Jill Donahue <jilliandonahue58@...il.com>
> Date: Thu, 6 Feb 2025 10:18:05 -0700
> Subject: [PATCH] f_midi_complete to call tasklet_hi_schedule

This all shouldn't be in the body of the email, please do not use web
email clients.  The kernel documentation should show you how to use git
send-email or other tools.

> 
> When using USB MIDI, a lock is attempted to be acquired twice through a
> re-entrant call to f_midi_transmit, causing a deadlock.
> 
> Fix it by using tasklet_hi_schedule() to schedule the inner
> f_midi_transmit() via a tasklet from the completion handler.
> 
> Link: https://lore.kernel.org/all/CAArt=LjxU0fUZOj06X+5tkeGT+6RbXzpWg1h4t4Fwa_KGVAX6g@mail.gmail.com/
> 
> Fixes: d5daf49b58661 ("USB: gadget: midi: add midi function driver")

No Cc: stable?

No blank line between Link: and Fixes: please

> Signed-off-by: Jill Donahue <jilliandonahue58@...il.com>
> ---
>  drivers/usb/gadget/function/f_midi.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

And this is a v2 patch, right?

> 
> diff --git a/drivers/usb/gadget/function/f_midi.c
> b/drivers/usb/gadget/function/f_midi.c
> index 837fcdfa3..37d438e5d 100644
> --- a/drivers/usb/gadget/function/f_midi.c
> +++ b/drivers/usb/gadget/function/f_midi.c
> @@ -283,7 +283,7 @@ f_midi_complete(struct usb_ep *ep, struct usb_request *req)
>                         /* Our transmit completed. See if there's more to go.
>                          * f_midi_transmit eats req, don't queue it again. */
>                         req->length = 0;
> -                       f_midi_transmit(midi);
> +                       tasklet_hi_schedule(&midi->tasklet);
>                         return;
>                 }

Your whitespace is all damaged and this can't be applied :(

thanks,

greg k-h