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From: Ed Tomlinson <edt@aei.ca>
To: Takashi Iwai <tiwai@suse.de>
Subject: Re: [LOCKDEP] 33-rc8 Running aplay with pulse as the default
Date: Mon, 15 Feb 2010 17:24:54 -0500
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Cc: "Rafael J. Wysocki" <rjw@sisk.pl>, linux-kernel@vger.kernel.org,
       alsa-devel@alsa-project.org
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On Monday 15 February 2010 14:21:55 Takashi Iwai wrote:
> At Mon, 15 Feb 2010 20:20:22 +0100,
> I wrote:
> > 
> > At Sat, 13 Feb 2010 12:17:10 -0500,
> > Ed Tomlinson wrote:
> > > 
> > > Hi,
> > > 
> > > Inorder to get skype working with linux I have the following in .asoundrc for my normal userid.
> > > 
> > > ---
> > > pcm.pulse {
> > >     type pulse
> > > }
> > > 
> > > ctl.pulse {
> > >     type pulse
> > > }
> > > 
> > > pcm.!default {
> > >     type pulse
> > > }
> > > ctl.!default {
> > >     type pulse
> > > ---
> > > 
> > > Try #1
> > > Starting as root if I do:
> > > su - <id>
> > > aplay sound.wav
> > > <traceback inlined below>
> > > aplay sound.wav 
> > > (silence)
> > > killall pulseaudio
> > > aplay sound.wav
> > > (works as expected now going thru pulseaudio)
> > > 
> > > Try #2
> > > Starting as root if I do:
> > > aplay sound.wav
> > > (works as expected using alsa alone)
> > > su - <id>
> > > aplay sound.wav
> > > <another lockdep traceback>
> > > aplay sound.wav
> > > (works as expected now going thru pulseaudio)
> > > 
> > > With .32 there were no tracebacks (lockdep was enabled) and try #1 would work where I now get silence.
> > > 
> > > Ideas?
> > > Ed Tomlinson
> > > 
> > > aplay -l
> > > **** List of PLAYBACK Hardware Devices ****
> > > card 0: SB [HDA ATI SB], device 0: ALC1200 Analog [ALC1200 Analog]
> > >   Subdevices: 0/1
> > >   Subdevice #0: subdevice #0
> > > card 0: SB [HDA ATI SB], device 1: ALC1200 Digital [ALC1200 Digital]
> > >   Subdevices: 1/1
> > >   Subdevice #0: subdevice #0
> > > card 1: HDMI [HDA ATI HDMI], device 3: ATI HDMI [ATI HDMI]
> > >   Subdevices: 1/1
> > >   Subdevice #0: subdevice #0
> > > 
> > > "ALC1200 Analog" is what has speakers connected
> > > 
> > > The em28xx in the traceback is an input source from a usb hdtv dongle.
> > > 
> > > pavucontrol setup has been verified.
> > > 
> > > [   91.070620]                                                                                                                               
> > > [   91.070621] =======================================================                                                                       
> > > [   91.071378] [ INFO: possible circular locking dependency detected ]                                                                       
> > > [   91.071378] 2.6.33-rc8-crc #106                                                                                                           
> > > [   91.071378] -------------------------------------------------------                                                                       
> > > [   91.071378] pulseaudio/2717 is trying to acquire lock:                                                                                    
> > > [   91.071378]  (&dev->lock){+.+.+.}, at: [<ffffffffa02797f1>] snd_em28xx_capture_open+0x61/0x190 [em28xx_alsa]                              
> > > [   91.071378]                                                                                                                               
> > > [   91.071378] but task is already holding lock:                                                                                             
> > > [   91.071378]  (&pcm->open_mutex){+.+.+.}, at: [<ffffffffa010ecd2>] snd_pcm_open+0x182/0x450 [snd_pcm]                                      
> > > [   91.071378]                                                                                                                               
> > > [   91.071378] which lock already depends on the new lock.                                                                                   
> > > [   91.071378]                                                                                                                               
> > > [   91.071378]                                                                                                                               
> > > [   91.071378] the existing dependency chain (in reverse order) is:                                                                          
> > > [   91.071378]                                                                                                                               
> > > [   91.071378] -> #3 (&pcm->open_mutex){+.+.+.}:                                                                                             
> > > [   91.071378]        [<ffffffff81083215>] __lock_acquire+0xfc5/0x1550                                                                       
> > > [   91.071378]        [<ffffffff8108383c>] lock_acquire+0x9c/0x140                                                                           
> > > [   91.071378]        [<ffffffff814b96c1>] __mutex_lock_common+0x61/0x610                                                                    
> > > [   91.071378]        [<ffffffff814b9d53>] mutex_lock_nested+0x43/0x50                                                                       
> > > [   91.071378]        [<ffffffffa010ad32>] snd_pcm_release+0x42/0xb0 [snd_pcm]                                                               
> > > [   91.071378]        [<ffffffff8112115d>] __fput+0x15d/0x290                                                                                
> > > [   91.071378]        [<ffffffff811212ad>] fput+0x1d/0x30                                                                                    
> > > [   91.071378]        [<ffffffff810fe001>] remove_vma+0x51/0x80                                                                              
> > > [   91.071378]        [<ffffffff810ffa1d>] do_munmap+0x2fd/0x390                                                                             
> > > [   91.071378]        [<ffffffff810ffb06>] sys_munmap+0x56/0x80                                                                              
> > > [   91.071378]        [<ffffffff81002adb>] system_call_fastpath+0x16/0x1b                                                                    
> > > [   91.071378]                                                                                                                               
> > > [   91.071378] -> #2 (&mm->mmap_sem){++++++}:                                                                                                
> > > [   91.071378]        [<ffffffff81083215>] __lock_acquire+0xfc5/0x1550                                                                       
> > > [   91.071378]        [<ffffffff8108383c>] lock_acquire+0x9c/0x140                                                                           
> > > [   91.071378]        [<ffffffff810f62c7>] might_fault+0xa7/0xd0                                                                             
> > > [   91.071378]        [<ffffffff8113102b>] filldir+0x7b/0xe0                                                                                 
> > > [   91.071378]        [<ffffffff8118aa21>] sysfs_readdir+0xf1/0x1b0                                                                          
> > > [   91.071378]        [<ffffffff81131268>] vfs_readdir+0xb8/0xe0                                                                             
> > > [   91.071378]        [<ffffffff8113144d>] sys_getdents+0xad/0x110                                                                           
> > > [   91.071378]        [<ffffffff81002adb>] system_call_fastpath+0x16/0x1b                                                                    
> > > [   91.071378]                                                                                                                               
> > > [   91.071378] -> #1 (sysfs_mutex){+.+.+.}:                                                                                                  
> > > [   91.071378]        [<ffffffff81083215>] __lock_acquire+0xfc5/0x1550                                                                       
> > > [   91.071378]        [<ffffffff8108383c>] lock_acquire+0x9c/0x140                                                                           
> > > [   91.071378]        [<ffffffff814b96c1>] __mutex_lock_common+0x61/0x610                                                                    
> > > [   91.071378]        [<ffffffff814b9d53>] mutex_lock_nested+0x43/0x50                                                                       
> > > [   91.071378]        [<ffffffff8118b082>] sysfs_addrm_start+0x22/0x30                                                                       
> > > [   91.071378]        [<ffffffff8118bc58>] create_dir+0x58/0xb0                                                                              
> > > [   91.514885]        [<ffffffff8118bd0a>] sysfs_create_dir+0x5a/0x70                                                                        
> > > [   91.514885]        [<ffffffff8123ebbd>] kobject_add_internal+0xbd/0x1f0                                                                   
> > > [   91.514885]        [<ffffffff8123ee08>] kobject_add_varg+0x38/0x60                                                                        
> > > [   91.514885]        [<ffffffff8123eee4>] kobject_add+0x44/0x70                                                                             
> > > [   91.514885]        [<ffffffff81392510>] device_add+0xb0/0x5e0                                                                             
> > > [   91.514885]        [<ffffffff81392a5e>] device_register+0x1e/0x30                                                                         
> > > [   91.514885]        [<ffffffff8140a50d>] i2c_register_adapter+0x12d/0x250                                                                  
> > > [   91.514885]        [<ffffffff8140a7f1>] i2c_add_adapter+0xb1/0xd0                                                                         
> > > [   91.514885]        [<ffffffffa0231ba4>] em28xx_i2c_register+0x104/0x520 [em28xx]                                                          
> > > [   91.514885]        [<ffffffffa0233daa>] em28xx_usb_probe+0x68a/0xb90 [em28xx]                                                             
> > > [   91.514885]        [<ffffffff813eb4ab>] usb_probe_interface+0xeb/0x1b0                                                                    
> > > [   91.514885]        [<ffffffff81395546>] driver_probe_device+0xc6/0x1d0                                                                    
> > > [   91.514885]        [<ffffffff813956eb>] __driver_attach+0x9b/0xa0                                                                         
> > > [   91.514885]        [<ffffffff8139492c>] bus_for_each_dev+0x6c/0xa0                                                                        
> > > [   91.514885]        [<ffffffff8139535e>] driver_attach+0x1e/0x20                                                                           
> > > [   91.514885]        [<ffffffff81394c11>] bus_add_driver+0xe1/0x280                                                                         
> > > [   91.514885]        [<ffffffff81395a58>] driver_register+0x98/0x140                                                                        
> > > [   91.514885]        [<ffffffff813ea06c>] usb_register_driver+0xdc/0x1a0                                                                    
> > > [   91.514885]        [<ffffffffa0248023>] 0xffffffffa0248023                                                                                
> > > [   91.514885]        [<ffffffff810001dc>] do_one_initcall+0x3c/0x1d0                                                                        
> > > [   91.514885]        [<ffffffff81092d75>] sys_init_module+0xe5/0x250                                                                        
> > > [   91.514885]        [<ffffffff81002adb>] system_call_fastpath+0x16/0x1b                                                                    
> > > [   91.514885]                                                                                                                               
> > > [   91.514885] -> #0 (&dev->lock){+.+.+.}:                                                                                                   
> > > [   91.514885]        [<ffffffff81083668>] __lock_acquire+0x1418/0x1550                                                                      
> > > [   91.514885]        [<ffffffff8108383c>] lock_acquire+0x9c/0x140                                                                           
> > > [   91.514885]        [<ffffffff814b96c1>] __mutex_lock_common+0x61/0x610                                                                    
> > > [   91.514885]        [<ffffffff814b9d53>] mutex_lock_nested+0x43/0x50
> > > [   91.514885]        [<ffffffffa02797f1>] snd_em28xx_capture_open+0x61/0x190 [em28xx_alsa]
> > > [   91.514885]        [<ffffffffa010adee>] snd_pcm_open_substream+0x4e/0x90 [snd_pcm]
> > > [   91.514885]        [<ffffffffa010ece9>] snd_pcm_open+0x199/0x450 [snd_pcm]
> > > [   91.514885]        [<ffffffffa010efd4>] snd_pcm_capture_open+0x34/0x40 [snd_pcm]
> > > [   91.514885]        [<ffffffffa00c5778>] snd_open+0x198/0x4e0 [snd]
> > > [   91.514885]        [<ffffffff8112384d>] chrdev_open+0x17d/0x320
> > > [   91.514885]        [<ffffffff8111d358>] __dentry_open+0x1a8/0x400
> > > [   91.514885]        [<ffffffff8111d6b4>] nameidata_to_filp+0x54/0x70
> > > [   91.514885]        [<ffffffff8112e7f1>] do_filp_open+0x841/0xc00
> > > [   91.514885]        [<ffffffff8111e954>] do_sys_open+0xa4/0x180
> > > [   91.514885]        [<ffffffff8111ea70>] sys_open+0x20/0x30
> > > [   91.514885]        [<ffffffff81002adb>] system_call_fastpath+0x16/0x1b
> > > [   91.514885]
> > > [   91.514885] other info that might help us debug this:
> > > [   91.514885]
> > > [   91.514885] 1 lock held by pulseaudio/2717:
> > > [   91.514885]  #0:  (&pcm->open_mutex){+.+.+.}, at: [<ffffffffa010ecd2>] snd_pcm_open+0x182/0x450 [snd_pcm]
> > > [   91.514885]
> > > [   91.514885] stack backtrace:
> > > [   91.514885] Pid: 2717, comm: pulseaudio Not tainted 2.6.33-rc8-crc #106
> > > [   91.514885] Call Trace:
> > > [   91.514885]  [<ffffffff81080fd9>] print_circular_bug+0xe9/0xf0
> > > [   91.514885]  [<ffffffff81083668>] __lock_acquire+0x1418/0x1550
> > > [   91.514885]  [<ffffffff81081dc8>] ? debug_check_no_locks_freed+0xc8/0x150
> > > [   91.514885]  [<ffffffff8108383c>] lock_acquire+0x9c/0x140
> > > [   91.514885]  [<ffffffffa02797f1>] ? snd_em28xx_capture_open+0x61/0x190 [em28xx_alsa]
> > > [   91.514885]  [<ffffffff814b96c1>] __mutex_lock_common+0x61/0x610
> > > [   91.514885]  [<ffffffffa02797f1>] ? snd_em28xx_capture_open+0x61/0x190 [em28xx_alsa]
> > > [   91.514885]  [<ffffffffa02797f1>] ? snd_em28xx_capture_open+0x61/0x190 [em28xx_alsa]
> > > [   91.514885]  [<ffffffffa0109c70>] ? snd_pcm_hw_rule_muldivk+0x0/0xa0 [snd_pcm]
> > > [   91.514885]  [<ffffffff8107fd54>] ? lockdep_init_map+0x44/0x130
> > > [   91.514885]  [<ffffffff814b9d53>] mutex_lock_nested+0x43/0x50
> > > [   91.514885]  [<ffffffffa02797f1>] snd_em28xx_capture_open+0x61/0x190 [em28xx_alsa]
> > > [   91.514885]  [<ffffffffa010adee>] snd_pcm_open_substream+0x4e/0x90 [snd_pcm]
> > > [   91.514885]  [<ffffffffa010ece9>] snd_pcm_open+0x199/0x450 [snd_pcm]
> > > [   91.514885]  [<ffffffff81081cfd>] ? trace_hardirqs_on+0xd/0x10
> > > [   91.514885]  [<ffffffff810434f0>] ? default_wake_function+0x0/0x20
> > > [   91.514885]  [<ffffffff814b965e>] ? mutex_unlock+0xe/0x10
> > > [   91.514885]  [<ffffffffa010efd4>] snd_pcm_capture_open+0x34/0x40 [snd_pcm]
> > > [   91.514885]  [<ffffffffa00c5778>] snd_open+0x198/0x4e0 [snd]
> > > [   91.514885]  [<ffffffff8112384d>] chrdev_open+0x17d/0x320
> > > [   91.514885]  [<ffffffff8111d358>] __dentry_open+0x1a8/0x400
> > > [   91.514885]  [<ffffffff811236d0>] ? chrdev_open+0x0/0x320
> > > [   91.514885]  [<ffffffff8111d6b4>] nameidata_to_filp+0x54/0x70
> > > [   91.514885]  [<ffffffff8112e7f1>] do_filp_open+0x841/0xc00
> > > [   91.514885]  [<ffffffff814bf981>] ? sub_preempt_count+0x51/0x60
> > > [   91.514885]  [<ffffffff814bbb7c>] ? _raw_spin_unlock+0x5c/0x70
> > > [   91.514885]  [<ffffffff8111e954>] do_sys_open+0xa4/0x180
> > > [   91.514885]  [<ffffffff8111ea70>] sys_open+0x20/0x30
> > > [   91.514885]  [<ffffffff81002adb>] system_call_fastpath+0x16/0x1b
> > > [   92.643423] hda-intel: IRQ timing workaround is activated for card #0. Suggest a bigger bdl_pos_adj.
> > 
> > It looks rather a bug of em28xx driver.  Changing dev->lock with an
> > individual one that is only for audio instance should fix the
> > problem.
> 
> And, I believe this is no regression but a long-standing problem.
> It hits just occasionally by an app like pulseauiod which loves
> tight races.

I guess it depends on how you define a regression.  From my POV it worked
in all three cases on .32, its failing in .33-rc and in one case is oppsing.  In
my books thats a regression.  There may have been races in .32 but they
did not trigger lockdep and never oppsed.

In any case, the real question is how do we fix the problem?

Ed
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