[PATCH v3] f_midi_complete to call tasklet_hi_schedule

Jill Donahue
2025-02-07T20:35:24Z

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")
Cc: stable@vger.kernel.org
Signed-off-by: Jill Donahue <jilliandonahue58@gmail.com>
---
drivers/usb/gadget/function/f_midi.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
index 837fcdfa3840..37d438e5d451 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;
}
break;
--
2.25.1