On 26. 04. 23 7:24, Takashi Iwai wrote:
On Tue, 25 Apr 2023 20:19:24 +0200,
Jakub Kicinski wrote:
Hi!
For a few weeks now I can't use any USB devices if I suspend my laptop
with my USB sound card active and resuming it without it connected.
USB worker threads seems to be sitting in:
[<0>] snd_pcm_dev_disconnect+0x1e8/0x280 [snd_pcm]
[<0>] snd_device_disconnect_all+0x42/0x80 [snd]
[<0>] snd_card_disconnect+0x128/0x290 [snd]
[<0>] usb_audio_disconnect+0x11a/0x2c0 [snd_usb_audio]
[<0>] usb_unbind_interface+0x8c/0x270
[<0>] device_release_driver_internal+0x1b2/0x230
[<0>] bus_remove_device+0xd8/0x150
[<0>] device_del+0x18b/0x410
[<0>] usb_disable_device+0xc6/0x1e0
[<0>] usb_disconnect+0xda/0x2c0
[<0>] usb_disconnect+0xbf/0x2c0
[<0>] usb_disconnect+0xbf/0x2c0
[<0>] usb_disconnect+0xbf/0x2c0
[<0>] hub_event+0xf01/0x1cd0
[<0>] process_one_work+0x1c4/0x3d0
[<0>] worker_thread+0x4d/0x380
[<0>] kthread+0xe6/0x110
[<0>] ret_from_fork+0x29/0x50
Which is:
snd_pcm_dev_disconnect (/usr/src/debug/kernel-6.2.12/linux-6.2.12-300.fc38.x86_64/sound/core/pcm.c:818 /usr/src/debug/kernel-6.2.12/linux-6.2.12-300.fc38.x86_64/sound/core/pcm.c:812 /usr/src/debug/kernel-6.2.12/linux-6.2.12-300.fc38.x86_64/sound/core/pcm.c:1129) snd_pcm
It happens on Fedora 37 and Fedora 38, it seems to have coincided with
the 6.2 kernel but I'm not 100% sure.
The USB devices come back after half an hour or so, silently.
There's nothing of note in dmesg.
AFAIK, there has been no similar report, so far.
Is it a regression? If yes, could you figure out which kernel version
starts showing the problem (or at best bisection)?
It seems that it may be related to free_chmap():
(gdb) l *(snd_pcm_dev_disconnect+0x1e8)
0xef0 is in snd_pcm_dev_disconnect (sound/core/pcm.c:817).
812 static void free_chmap(struct snd_pcm_str *pstr)
813 {
814 if (pstr->chmap_kctl) {
815 struct snd_card *card = pstr->pcm->card;
816
817 down_write(&card->controls_rwsem);
818 snd_ctl_remove(card, pstr->chmap_kctl);
819 up_write(&card->controls_rwsem);
820 pstr->chmap_kctl = NULL;
821 }
I think that the chmap should be freed only in snd_pcm_free_stream() to avoid
possible nested mutex locks. This operation does not belong to disconnect.
But I cannot reproduce this lock here.
Jaroslav
--
Jaroslav Kysela <perex@xxxxxxxx>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.
