On 31-03-20, 10:54, 이경택 wrote: > Hi, > > On 30-03-20, 17:17, Vinod Koul wrote: > >Hello, > > > >On 30-03-20, 20:01, ̰ wrote: > >> snd_soc_runtime_activate() and snd_soc_runtime_deactivate() require > >> locked pcm_mutex. > >> > >> Signed-off-by: Gyeongtaek Lee <gt82.lee@xxxxxxxxxxx> > >> --- > >> sound/soc/soc-compress.c | 4 ++++ > >> 1 file changed, 4 insertions(+) > >> > >> diff --git a/sound/soc/soc-compress.c b/sound/soc/soc-compress.c index > >> 392a1c5b15d3..42d416ac7e9b 100644 > >> --- a/sound/soc/soc-compress.c > >> +++ b/sound/soc/soc-compress.c > >> @@ -207,7 +207,9 @@ static int soc_compr_open_fe(struct > >> snd_compr_stream > >> *cstream) > >> fe->dpcm[stream].state = SND_SOC_DPCM_STATE_OPEN; > >> fe->dpcm[stream].runtime_update = SND_SOC_DPCM_UPDATE_NO; > >> > >> + mutex_lock_nested(&fe->pcm_mutex, fe->pcm_subclass); > >> snd_soc_runtime_activate(fe, stream); > >> + mutex_unlock(&fe->pcm_mutex); > > > >Can you please explain why you need the lock here, as > >> > >> mutex_unlock(&fe->card->mutex); > > > >we already have a lock here.. > > > >> @@ -285,7 +287,9 @@ static int soc_compr_free_fe(struct > >> snd_compr_stream > >> *cstream) > >> else > >> stream = SNDRV_PCM_STREAM_CAPTURE; > >> > >> + mutex_lock_nested(&fe->pcm_mutex, fe->pcm_subclass); > >> snd_soc_runtime_deactivate(fe, stream); > >> + mutex_unlock(&fe->pcm_mutex); > > > >And this instance is also using fe->card->mutex.. so I think double lock may not serve any purpose here.. > > > >Can you explain why we need the extra lock? > You are right. > The mutex_lock with fe->pcm_mutex has no purpose. Okay > It just removes lockdep warning like the below > <4>[ 1437.857354] [5: cplay:11547] ------------[ cut here ]------------ > <4>[ 1437.857463] [5: cplay:11547] WARNING: CPU: 5 PID: 11547 at sound/soc/soc-pcm.c:99 snd_soc_runtime_deactivate+0x88/0x140 > <4>[ 1437.857498] [5: cplay:11547] Modules linked in: > <4>[ 1437.857557] [5: cplay:11547] CPU: 5 PID: 11547 Comm: cplay Tainted: G S W 4.19.65-00198-ge6c3a8b64f3d-dirty #146 > <4>[ 1437.857590] [5: cplay:11547] Hardware name: Samsung xxx board based on xxx (DT) > <4>[ 1437.857620] [5: cplay:11547] Call trace: > <4>[ 1437.857662] [5: cplay:11547] [<ffffff800808d598>] dump_backtrace+0x0/0x404 > <4>[ 1437.857704] [5: cplay:11547] [<ffffff800808d9b0>] show_stack+0x14/0x1c > <4>[ 1437.857745] [5: cplay:11547] [<ffffff8008c5dc24>] dump_stack+0xa0/0xd8 > <4>[ 1437.857784] [5: cplay:11547] [<ffffff80080a4b28>] __warn+0xcc/0x12c > <4>[ 1437.857821] [5: cplay:11547] [<ffffff8008c5cd78>] report_bug+0x78/0xcc > <4>[ 1437.857857] [5: cplay:11547] [<ffffff800808e5c0>] bug_handler+0x2c/0x88 > <4>[ 1437.857895] [5: cplay:11547] [<ffffff8008085510>] brk_handler+0x88/0xc8 > <4>[ 1437.857930] [5: cplay:11547] [<ffffff8008080f0c>] do_debug_exception+0x108/0x194 > <4>[ 1437.857968] [5: cplay:11547] Exception stack(0xffffff8028b0b960 to 0xffffff8028b0baa0) > <4>[ 1437.858002] [5: cplay:11547] b960: 0000000000000024 ffffff8008e28a97 ffffffc975bb40a0 ffffff8028b0b748 > <4>[ 1437.858035] [5: cplay:11547] b980: 0000000000000080 0000000000000000 ffffff8008129638 0000000000000000 > <4>[ 1437.858066] [5: cplay:11547] b9a0: e0b1dc92eba18f00 e0b1dc92eba18f00 0000000000000003 0000000000000000 > <4>[ 1437.858098] [5: cplay:11547] b9c0: 0000000000240022 0000000000000004 ffffff8009b2f420 00000000fffffff5 > <4>[ 1437.858130] [5: cplay:11547] b9e0: ffffff8008c6baac 000000000000002c 00000000000000b0 ffffffc9673c1e80 > <4>[ 1437.858161] [5: cplay:11547] ba00: 0000000000000000 ffffffc8190e6100 0000000000000000 ffffffc95c262e88 > <4>[ 1437.858193] [5: cplay:11547] ba20: 0000000000000008 ffffffc8ec3050d0 ffffffc8fb81a4d0 0000000000000004 > <4>[ 1437.858224] [5: cplay:11547] ba40: 0000000000000009 ffffff8028b0bac0 ffffff8008a895c8 ffffff8028b0baa0 > <4>[ 1437.858256] [5: cplay:11547] ba60: ffffff8008a895c8 0000000060400005 ffffff8028b0ba48 ffffff800811d7b4 > <4>[ 1437.858287] [5: cplay:11547] ba80: 0000007fffffffff e0b1dc92eba18f00 ffffff8028b0bac0 ffffff8008a895c8 > <4>[ 1437.858318] [5: cplay:11547] [<ffffff8008082b18>] el1_dbg+0x18/0x78 > <4>[ 1437.858355] [5: cplay:11547] [<ffffff8008a895c8>] snd_soc_runtime_deactivate+0x88/0x140 So if the lockdep is complaining, then we should add lockdep assert in the open_fe as well.. -- ~Vinod
