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ALSA: rawmidi: Another workaround for false-positive mutex lockdep warning

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While we attempted to work around the false-positive lockdep warning
due to the nested mutex lock in rawmidi at the open path for a UMP
legacy rawmidi, it didn't cover the similar locking at its close path,
and this still caused another false-positive reports by syzkaller.

Add a similar workaround to snd_rawmidi_kernel_release() as done in
the former commit 9c04742e73 ("ALSA: rawmidi: Work around
false-positive mutex lockdep warning") to cover completely.

Reported-by: syzbot+7d1edf0ff6a05961020c@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/6a8c7e4d.4d75e56a.c9a88.0052.GAE@google.com
Link: https://patch.msgid.link/20260825134942.1289272-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai
2026-08-25 15:49:31 +02:00
parent adb176c140
commit 58c1c30074
3 changed files with 16 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
include/sound/rawmidi.h
View File

@@ -179,7 +179,8 @@ int snd_rawmidi_info_select(struct snd_card *card, struct snd_rawmidi_info *info
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_kernel_release_nested(struct snd_rawmidi_file *rfile,
int depth);
int snd_rawmidi_output_params(struct snd_rawmidi_substream *substream,
struct snd_rawmidi_params *params);
int snd_rawmidi_input_params(struct snd_rawmidi_substream *substream,
@@ -201,6 +202,11 @@ static inline int snd_rawmidi_kernel_open(struct snd_rawmidi *rmidi,
return snd_rawmidi_kernel_open_nested(rmidi, subdevice, mode, rfile, 0);
}
static inline int snd_rawmidi_kernel_release(struct snd_rawmidi_file *rfile)
{
return snd_rawmidi_kernel_release_nested(rfile, 0);
}
/* set up the tied devices */
static inline void snd_rawmidi_tie_devices(struct snd_rawmidi *r1,
struct snd_rawmidi *r2)

11
sound/core/rawmidi.c
View File

@@ -571,7 +571,6 @@ static void rawmidi_release_priv(struct snd_rawmidi_file *rfile)
struct snd_rawmidi *rmidi;
rmidi = rfile->rmidi;
guard(mutex)(&rmidi->open_mutex);
if (rfile->input) {
close_substream(rmidi, rfile->input, 1);
rfile->input = NULL;
@@ -585,7 +584,8 @@ static void rawmidi_release_priv(struct snd_rawmidi_file *rfile)
}
/* called from sound/core/seq/seq_midi.c */
int snd_rawmidi_kernel_release(struct snd_rawmidi_file *rfile)
int snd_rawmidi_kernel_release_nested(struct snd_rawmidi_file *rfile,
int depth)
{
struct snd_rawmidi *rmidi;
@@ -593,11 +593,13 @@ int snd_rawmidi_kernel_release(struct snd_rawmidi_file *rfile)
return -ENXIO;
rmidi = rfile->rmidi;
mutex_lock_nested(&rmidi->open_mutex, depth);
rawmidi_release_priv(rfile);
mutex_unlock(&rmidi->open_mutex);
module_put(rmidi->card->module);
return 0;
}
EXPORT_SYMBOL(snd_rawmidi_kernel_release);
EXPORT_SYMBOL(snd_rawmidi_kernel_release_nested);
static int snd_rawmidi_release(struct inode *inode, struct file *file)
{
@@ -607,7 +609,8 @@ static int snd_rawmidi_release(struct inode *inode, struct file *file)
rfile = file->private_data;
rmidi = rfile->rmidi;
rawmidi_release_priv(rfile);
scoped_guard(mutex, &rmidi->open_mutex)
rawmidi_release_priv(rfile);
kfree(rfile);
module = rmidi->card->module;
snd_card_file_remove(rmidi->card, file);

3
sound/core/ump.c
View File

@@ -1184,7 +1184,8 @@ static int snd_ump_legacy_close(struct snd_rawmidi_substream *substream)
ump->legacy_substreams[dir][group] = NULL;
if (dir == SNDRV_RAWMIDI_STREAM_OUTPUT) {
if (!--ump->legacy_out_opens)
snd_rawmidi_kernel_release(&ump->legacy_out_rfile);
snd_rawmidi_kernel_release_nested(&ump->legacy_out_rfile,
SINGLE_DEPTH_NESTING);
}
return 0;
}