5.4-stable review patch. If anyone has any objections, please let me know.
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From: Davidlohr Bueso dave@stgolabs.net
[ Upstream commit 8653d71ce3763aedcf3d2331f59beda3fecd79e4 ]
Currently a tasklet is used to transmit input substream buffer data. However, tasklets have long been deprecated as being too heavy on the system by running in irq context - and this is not a performance critical path. If a higher priority process wants to run, it must wait for the tasklet to finish before doing so.
Deferring work to a workqueue and executing in process context should be fine considering the callback already does f_midi_do_transmit() under the transmit_lock and thus changes in semantics are ok regarding concurrency - tasklets being serialized against itself.
Cc: Takashi Iwai tiwai@suse.de Reviewed-by: Takashi Iwai tiwai@suse.de Acked-by: Felipe Balbi balbi@kernel.org Signed-off-by: Davidlohr Bueso dbueso@suse.de Link: https://lore.kernel.org/r/20210111042855.73289-1-dave@stgolabs.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Stable-dep-of: 4ab37fcb4283 ("USB: gadget: f_midi: f_midi_complete to call queue_work") Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/usb/gadget/function/f_midi.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c index 71aeaa2302edd..01c5736d381ef 100644 --- a/drivers/usb/gadget/function/f_midi.c +++ b/drivers/usb/gadget/function/f_midi.c @@ -87,7 +87,7 @@ struct f_midi { struct snd_rawmidi_substream *out_substream[MAX_PORTS];
unsigned long out_triggered; - struct tasklet_struct tasklet; + struct work_struct work; unsigned int in_ports; unsigned int out_ports; int index; @@ -698,9 +698,11 @@ static void f_midi_transmit(struct f_midi *midi) f_midi_drop_out_substreams(midi); }
-static void f_midi_in_tasklet(struct tasklet_struct *t) +static void f_midi_in_work(struct work_struct *work) { - struct f_midi *midi = from_tasklet(midi, t, tasklet); + struct f_midi *midi; + + midi = container_of(work, struct f_midi, work); f_midi_transmit(midi); }
@@ -737,7 +739,7 @@ static void f_midi_in_trigger(struct snd_rawmidi_substream *substream, int up) VDBG(midi, "%s() %d\n", __func__, up); midi->in_ports_array[substream->number].active = up; if (up) - tasklet_hi_schedule(&midi->tasklet); + queue_work(system_highpri_wq, &midi->work); }
static int f_midi_out_open(struct snd_rawmidi_substream *substream) @@ -875,7 +877,7 @@ static int f_midi_bind(struct usb_configuration *c, struct usb_function *f) int status, n, jack = 1, i = 0, endpoint_descriptor_index = 0;
midi->gadget = cdev->gadget; - tasklet_setup(&midi->tasklet, f_midi_in_tasklet); + INIT_WORK(&midi->work, f_midi_in_work); status = f_midi_register_card(midi); if (status < 0) goto fail_register;