| Message ID | 20220322170720.3529-4-tiwai@suse.de |
|---|---|
| State | Accepted |
| Commit | 3c3201f8c7bb77eb53b08a3ca8d9a4ddc500b4c0 |
| Headers | show |
| Series | ALSA: pcm: Fix ioctl races | expand |
On 3/22/2022 6:07 PM, Takashi Iwai wrote: > Like the previous fixes to hw_params and hw_free ioctl races, we need > to paper over the concurrent prepare ioctl calls against hw_params and > hw_free, too. > > This patch implements the locking with the existing > runtime->buffer_mutex for prepare ioctls. Unlike the previous case > for snd_pcm_hw_hw_params() and snd_pcm_hw_free(), snd_pcm_prepare() is > performed to the linked streams, hence the lock can't be applied > simply on the top. For tracking the lock in each linked substream, we > modify snd_pcm_action_group() slightly and apply the buffer_mutex for > the case stream_lock=false (formerly there was no lock applied) > there. > > Cc: <stable@vger.kernel.org> > Signed-off-by: Takashi Iwai <tiwai@suse.de> > --- > sound/core/pcm_native.c | 32 ++++++++++++++++++-------------- > 1 file changed, 18 insertions(+), 14 deletions(-) > > diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c > index 266895374b83..0e4fbf5fd87b 100644 > --- a/sound/core/pcm_native.c > +++ b/sound/core/pcm_native.c > @@ -1190,15 +1190,17 @@ struct action_ops { > static int snd_pcm_action_group(const struct action_ops *ops, > struct snd_pcm_substream *substream, > snd_pcm_state_t state, > - bool do_lock) > + bool stream_lock) > { > struct snd_pcm_substream *s = NULL; > struct snd_pcm_substream *s1; > int res = 0, depth = 1; > > snd_pcm_group_for_each_entry(s, substream) { > - if (do_lock && s != substream) { > - if (s->pcm->nonatomic) > + if (s != substream) { > + if (!stream_lock) > + mutex_lock_nested(&s->runtime->buffer_mutex, depth); > + else if (s->pcm->nonatomic) > mutex_lock_nested(&s->self_group.mutex, depth); > else > spin_lock_nested(&s->self_group.lock, depth); Maybe if (!stream_lock) mutex_lock_nested(&s->runtime->buffer_mutex, depth); else snd_pcm_group_lock(&s->self_group, s->pcm->nonatomic); ? > @@ -1226,18 +1228,18 @@ static int snd_pcm_action_group(const struct action_ops *ops, > ops->post_action(s, state); > } > _unlock: > - if (do_lock) { > - /* unlock streams */ > - snd_pcm_group_for_each_entry(s1, substream) { > - if (s1 != substream) { > - if (s1->pcm->nonatomic) > - mutex_unlock(&s1->self_group.mutex); > - else > - spin_unlock(&s1->self_group.lock); > - } > - if (s1 == s) /* end */ > - break; > + /* unlock streams */ > + snd_pcm_group_for_each_entry(s1, substream) { > + if (s1 != substream) { > + if (!stream_lock) > + mutex_unlock(&s1->runtime->buffer_mutex); > + else if (s1->pcm->nonatomic) > + mutex_unlock(&s1->self_group.mutex); > + else > + spin_unlock(&s1->self_group.lock); And similarly to above, use snd_pcm_group_unlock() here? > } > + if (s1 == s) /* end */ > + break; > } > return res; > } > @@ -1367,10 +1369,12 @@ static int snd_pcm_action_nonatomic(const struct action_ops *ops, > > /* Guarantee the group members won't change during non-atomic action */ > down_read(&snd_pcm_link_rwsem); > + mutex_lock(&substream->runtime->buffer_mutex); > if (snd_pcm_stream_linked(substream)) > res = snd_pcm_action_group(ops, substream, state, false); > else > res = snd_pcm_action_single(ops, substream, state); > + mutex_unlock(&substream->runtime->buffer_mutex); > up_read(&snd_pcm_link_rwsem); > return res; > }
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index 266895374b83..0e4fbf5fd87b 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -1190,15 +1190,17 @@ struct action_ops { static int snd_pcm_action_group(const struct action_ops *ops, struct snd_pcm_substream *substream, snd_pcm_state_t state, - bool do_lock) + bool stream_lock) { struct snd_pcm_substream *s = NULL; struct snd_pcm_substream *s1; int res = 0, depth = 1; snd_pcm_group_for_each_entry(s, substream) { - if (do_lock && s != substream) { - if (s->pcm->nonatomic) + if (s != substream) { + if (!stream_lock) + mutex_lock_nested(&s->runtime->buffer_mutex, depth); + else if (s->pcm->nonatomic) mutex_lock_nested(&s->self_group.mutex, depth); else spin_lock_nested(&s->self_group.lock, depth); @@ -1226,18 +1228,18 @@ static int snd_pcm_action_group(const struct action_ops *ops, ops->post_action(s, state); } _unlock: - if (do_lock) { - /* unlock streams */ - snd_pcm_group_for_each_entry(s1, substream) { - if (s1 != substream) { - if (s1->pcm->nonatomic) - mutex_unlock(&s1->self_group.mutex); - else - spin_unlock(&s1->self_group.lock); - } - if (s1 == s) /* end */ - break; + /* unlock streams */ + snd_pcm_group_for_each_entry(s1, substream) { + if (s1 != substream) { + if (!stream_lock) + mutex_unlock(&s1->runtime->buffer_mutex); + else if (s1->pcm->nonatomic) + mutex_unlock(&s1->self_group.mutex); + else + spin_unlock(&s1->self_group.lock); } + if (s1 == s) /* end */ + break; } return res; } @@ -1367,10 +1369,12 @@ static int snd_pcm_action_nonatomic(const struct action_ops *ops, /* Guarantee the group members won't change during non-atomic action */ down_read(&snd_pcm_link_rwsem); + mutex_lock(&substream->runtime->buffer_mutex); if (snd_pcm_stream_linked(substream)) res = snd_pcm_action_group(ops, substream, state, false); else res = snd_pcm_action_single(ops, substream, state); + mutex_unlock(&substream->runtime->buffer_mutex); up_read(&snd_pcm_link_rwsem); return res; }
Like the previous fixes to hw_params and hw_free ioctl races, we need to paper over the concurrent prepare ioctl calls against hw_params and hw_free, too. This patch implements the locking with the existing runtime->buffer_mutex for prepare ioctls. Unlike the previous case for snd_pcm_hw_hw_params() and snd_pcm_hw_free(), snd_pcm_prepare() is performed to the linked streams, hence the lock can't be applied simply on the top. For tracking the lock in each linked substream, we modify snd_pcm_action_group() slightly and apply the buffer_mutex for the case stream_lock=false (formerly there was no lock applied) there. Cc: <stable@vger.kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de> --- sound/core/pcm_native.c | 32 ++++++++++++++++++-------------- 1 file changed, 18 insertions(+), 14 deletions(-)