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| author | Takashi Iwai <tiwai@suse.de> | 2026-08-06 12:13:51 +0200 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2026-08-06 17:02:22 +0200 |
| commit | 9c04742e73b32fb3912e1d9fb9f804affb340dce (patch) | |
| tree | f95bf5a7c4f000cfe487e3b8c89d4aa516e9601e /include | |
| parent | 02442d5fe8ee365a084b055d4fa81a0c1abfc3fd (diff) | |
| download | linux-stable-9c04742e73b32fb3912e1d9fb9f804affb340dce.tar.gz linux-stable-9c04742e73b32fb3912e1d9fb9f804affb340dce.zip | |
ALSA: rawmidi: Work around false-positive mutex lockdep warning
When opening a legacy rawmidi device for a UMP, it may re-open an
existing rawmidi device for appending to a substream, leading to a
lockdep warning due to rmidi->open_mutex taken twice -- but the
rawmidi devices are completely individual, hence it's a
false-positive.
For avoiding the warning, modify the helper to open a rawmidi instance
with a proper locking subclass from the UMP legacy open.
Unfortunately, there is no good way to achieve it with guard(), so
reverted to the manual mutex calls again.
Reported-by: syzbot+d10d58fc99caa0489796@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/6a6a9634.57649fcc.360844.000b.GAE@google.com
Link: https://patch.msgid.link/20260806101352.1291581-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'include')
| -rw-r--r-- | include/sound/rawmidi.h | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/include/sound/rawmidi.h b/include/sound/rawmidi.h index 6916f7133597..88a6159364d0 100644 --- a/include/sound/rawmidi.h +++ b/include/sound/rawmidi.h @@ -176,8 +176,9 @@ int snd_rawmidi_proceed(struct snd_rawmidi_substream *substream); /* main midi functions */ int snd_rawmidi_info_select(struct snd_card *card, struct snd_rawmidi_info *info); -int snd_rawmidi_kernel_open(struct snd_rawmidi *rmidi, int subdevice, - int mode, struct snd_rawmidi_file *rfile); +int snd_rawmidi_kernel_open_nested(struct snd_rawmidi *rmidi, int subdevice, + int mode, struct snd_rawmidi_file *rfile, + int depth); int snd_rawmidi_kernel_release(struct snd_rawmidi_file *rfile); int snd_rawmidi_output_params(struct snd_rawmidi_substream *substream, struct snd_rawmidi_params *params); @@ -191,6 +192,15 @@ long snd_rawmidi_kernel_read(struct snd_rawmidi_substream *substream, long snd_rawmidi_kernel_write(struct snd_rawmidi_substream *substream, const unsigned char *buf, long count); +/* non-nested version */ +static inline int snd_rawmidi_kernel_open(struct snd_rawmidi *rmidi, + int subdevice, + int mode, + struct snd_rawmidi_file *rfile) +{ + return snd_rawmidi_kernel_open_nested(rmidi, subdevice, mode, rfile, 0); +} + /* set up the tied devices */ static inline void snd_rawmidi_tie_devices(struct snd_rawmidi *r1, struct snd_rawmidi *r2) |