From: Takashi Iwai tiwai@suse.de

[ Upstream commit 4974b7950929e4a28d4eaee48e4ad07f168ac132 ]

The PCM trigger callback is atomic, hence we must not call a function like usb_set_interface() there. Calling it from there would lead to a kernel Oops.

Fix it by moving the usb_set_interface() call to set_sync_endpoint().

Also, apply the snd_usb_set_interface_quirk() for consistency, too.

Tested-by: Keith Milner kamilner@superlative.org Tested-by: Dylan Robinson dylan_robinson@motu.com Link: https://lore.kernel.org/r/20201123085347.19667-3-tiwai@suse.de Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Sasha Levin sashal@kernel.org --- sound/usb/pcm.c | 28 +++++++++++++--------------- 1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c index 95d02e25a3133..77c704847e4ac 100644 --- a/sound/usb/pcm.c +++ b/sound/usb/pcm.c @@ -242,21 +242,6 @@ static int start_endpoints(struct snd_usb_substream *subs) !test_and_set_bit(SUBSTREAM_FLAG_SYNC_EP_STARTED, &subs->flags)) { struct snd_usb_endpoint *ep = subs->sync_endpoint;

- if (subs->data_endpoint->iface != subs->sync_endpoint->iface || - subs->data_endpoint->altsetting != subs->sync_endpoint->altsetting) { - err = usb_set_interface(subs->dev, - subs->sync_endpoint->iface, - subs->sync_endpoint->altsetting); - if (err < 0) { - clear_bit(SUBSTREAM_FLAG_SYNC_EP_STARTED, &subs->flags); - dev_err(&subs->dev->dev, - "%d:%d: cannot set interface (%d)\n", - subs->sync_endpoint->iface, - subs->sync_endpoint->altsetting, err); - return -EIO; - } - } - dev_dbg(&subs->dev->dev, "Starting sync EP @%p\n", ep);

ep->sync_slave = subs->data_endpoint; @@ -499,6 +484,19 @@ static int set_sync_endpoint(struct snd_usb_substream *subs,

subs->data_endpoint->sync_master = subs->sync_endpoint;

+ if (subs->data_endpoint->iface != subs->sync_endpoint->iface || + subs->data_endpoint->altsetting != subs->sync_endpoint->altsetting) { + err = usb_set_interface(subs->dev, + subs->sync_endpoint->iface, + subs->sync_endpoint->altsetting); + if (err < 0) + return err; + dev_dbg(&dev->dev, "setting usb interface %d:%d\n", + subs->sync_endpoint->iface, + subs->sync_endpoint->altsetting); + snd_usb_set_interface_quirk(dev); + } + return 0; }