Messages in this thread Patch in this message | | | Date | Thu, 08 Jan 2009 17:53:31 +0100 | From | Takashi Iwai <> | Subject | Re: [bug] sound: INFO: possible recursive locking detected |
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At Thu, 08 Jan 2009 17:17:06 +0100, I wrote: > > At Thu, 08 Jan 2009 17:12:54 +0100, > Peter Zijlstra wrote: > > > > On Thu, 2009-01-08 at 17:10 +0100, Takashi Iwai wrote: > > > At Thu, 08 Jan 2009 16:39:31 +0100, > > > I wrote: > > > > > > > > At Thu, 8 Jan 2009 16:20:37 +0100, > > > > Ingo Molnar wrote: > > > > > > > > > > FYI, -tip testing found this new lockdep workqueue locking assert > > > > > triggered by the Intel HDA sound driver: > > > (snip) > > > > > [ 30.718689] ============================================= > > > > > [ 30.718689] [ INFO: possible recursive locking detected ] > > > > > [ 30.718689] 2.6.28-tip #2 > > > > > [ 30.718689] --------------------------------------------- > > > > > [ 30.718689] events/0/7 is trying to acquire lock: > > > > > [ 30.718689] (events){--..}, at: [<ffffffff80281050>] flush_workqueue+0x0/0x90 > > > > > [ 30.718689] > > > > > [ 30.718689] but task is already holding lock: > > > > > [ 30.718689] (events){--..}, at: [<ffffffff8028076a>] run_workqueue+0x14a/0x240 > > > > > [ 30.718689] > > > > > [ 30.718689] other info that might help us debug this: > > > > > [ 30.718689] 2 locks held by events/0/7: > > > > > [ 30.718689] #0: (events){--..}, at: [<ffffffff8028076a>] run_workqueue+0x14a/0x240 > > > > > [ 30.718689] #1: (&wfc.work){--..}, at: [<ffffffff8028076a>] run_workqueue+0x14a/0x240 > > > > > [ 30.718689] > > > > > [ 30.718689] stack backtrace: > > > > > [ 30.718689] Pid: 7, comm: events/0 Not tainted 2.6.28-tip #2 > > > > > [ 30.718689] Call Trace: > > > > > [ 30.718689] [<ffffffff80295836>] validate_chain+0xc56/0x1340 > > > > > [ 30.718689] [<ffffffff802974e6>] __lock_acquire+0x376/0x610 > > > > > [ 30.718689] [<ffffffff80297819>] lock_acquire+0x99/0xd0 > > > > > [ 30.718689] [<ffffffff80281050>] ? flush_workqueue+0x0/0x90 > > > > > [ 30.718689] [<ffffffff80281091>] flush_workqueue+0x41/0x90 > > > > > [ 30.718689] [<ffffffff80281050>] ? flush_workqueue+0x0/0x90 > > > > > [ 30.718689] [<ffffffff802810f5>] flush_scheduled_work+0x15/0x20 > > > > > [ 30.718689] [<ffffffff80c59794>] azx_clear_irq_pending+0x54/0x60 > > > > > [ 30.718689] [<ffffffff80c599ec>] azx_free+0x10c/0x160 > > > > > [ 30.718689] [<ffffffff80bae9ad>] ? snd_device_free+0x8d/0x100 > > > > > [ 30.718689] [<ffffffff80c59a52>] azx_dev_free+0x12/0x20 > > > > > [ 30.718689] [<ffffffff80bae9a1>] snd_device_free+0x81/0x100 > > > > > [ 30.718689] [<ffffffff80baea89>] snd_device_free_all+0x69/0xa0 > > > > > [ 30.718689] [<ffffffff80ba8a70>] snd_card_do_free+0x50/0xd0 > > > > > [ 30.718689] [<ffffffff80ba9602>] snd_card_free+0xa2/0xc0 > > > > > [ 30.718689] [<ffffffff8061115f>] ? __delay+0xf/0x20 > > > > > [ 30.718689] [<ffffffff80edbb6a>] azx_probe+0x38a/0x9f0 > > > > > [ 30.718689] [<ffffffff80c5a240>] ? azx_send_cmd+0x0/0x130 > > > > > [ 30.718689] [<ffffffff80c5a370>] ? azx_get_response+0x0/0x210 > > > > > [ 30.718689] [<ffffffff80c59b70>] ? azx_attach_pcm_stream+0x0/0x1b0 > > > > > [ 30.718689] [<ffffffff802804d0>] ? do_work_for_cpu+0x0/0x30 > > > > > [ 30.718689] [<ffffffff80634807>] local_pci_probe+0x17/0x20 > > > > > [ 30.718689] [<ffffffff802804e8>] do_work_for_cpu+0x18/0x30 > > > > > [ 30.718689] [<ffffffff802804d0>] ? do_work_for_cpu+0x0/0x30 > > > > > [ 30.718689] [<ffffffff802807bb>] run_workqueue+0x19b/0x240 > > > > > [ 30.718689] [<ffffffff8028076a>] ? run_workqueue+0x14a/0x240 > > > > > [ 30.718689] [<ffffffff802809cf>] worker_thread+0xaf/0x110 > > > > > [ 30.718689] [<ffffffff80284e20>] ? autoremove_wake_function+0x0/0x40 > > > > > [ 30.718689] [<ffffffff80280920>] ? worker_thread+0x0/0x110 > > > > > [ 30.718689] [<ffffffff802848e3>] kthread+0x53/0x80 > > > > > [ 30.718689] [<ffffffff8022c3aa>] child_rip+0xa/0x20 > > > > > [ 30.718689] [<ffffffff8022bcbe>] ? restore_args+0x0/0x30 > > > > > [ 30.718689] [<ffffffff80284890>] ? kthread+0x0/0x80 > > > > > [ 30.718689] [<ffffffff8022c3a0>] ? child_rip+0x0/0x20 > > > > > > The backtrace implies that the probe callback is called in a > > > workqueue. Is it right? > > > > Yes, it appears a worklet tries to flush the queue he's on. > > It calls flush_schedule_work(). > So, now this should be avoided during the probe callback? > > If so, a simple workaround would be to create its own workqueue, or > add a flag to avoid this call at destructor...
The below is a quick fix to convert to use the own workq in hda_intel.c. This should fix this particular lockdep problem, at least. (And it's better, anyway.)
Please give it a try.
thanks,
Takashi
--- diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c index f04de11..7e09f98 100644 --- a/sound/pci/hda/hda_intel.c +++ b/sound/pci/hda/hda_intel.c @@ -406,6 +406,7 @@ struct azx { unsigned int last_cmd; /* last issued command (to sync) */ /* for pending irqs */ + struct workqueue_struct *workq; struct work_struct irq_pending_work; /* reboot notifier (for mysterious hangup problem at power-down) */ @@ -999,7 +1000,8 @@ static irqreturn_t azx_interrupt(int irq, void *dev_id) } else { /* bogus IRQ, process it later */ azx_dev->irq_pending = 1; - schedule_work(&chip->irq_pending_work); + queue_work(chip->workq, + &chip->irq_pending_work); } } } @@ -1741,7 +1743,7 @@ static void azx_clear_irq_pending(struct azx *chip) for (i = 0; i < chip->num_streams; i++) chip->azx_dev[i].irq_pending = 0; spin_unlock_irq(&chip->reg_lock); - flush_scheduled_work(); + flush_workqueue(chip->workq); } static struct snd_pcm_ops azx_pcm_ops = { @@ -2019,6 +2021,8 @@ static int azx_free(struct azx *chip) azx_stop_chip(chip); } + if (chip->workq) + destroy_workqueue(chip->workq); if (chip->irq >= 0) free_irq(chip->irq, (void*)chip); if (chip->msi) @@ -2131,6 +2135,7 @@ static int __devinit azx_create(struct snd_card *card, struct pci_dev *pci, static struct snd_device_ops ops = { .dev_free = azx_dev_free, }; + char qname[8]; *rchip = NULL; @@ -2153,7 +2158,6 @@ static int __devinit azx_create(struct snd_card *card, struct pci_dev *pci, chip->driver_type = driver_type; chip->msi = enable_msi; chip->dev_index = dev; - INIT_WORK(&chip->irq_pending_work, azx_irq_pending_work); chip->position_fix = check_position_fix(chip, position_fix[dev]); check_probe_mask(chip, dev); @@ -2200,6 +2204,15 @@ static int __devinit azx_create(struct snd_card *card, struct pci_dev *pci, if (pci_enable_msi(pci) < 0) chip->msi = 0; + snprintf(qname, sizeof(qname), "hda%d", chip->card->number); + chip->workq = create_workqueue(qname); + if (!chip->workq) { + snd_printk(KERN_ERR SFX "cannot create workqueue %s\n", qname); + err = -ENOMEM; + goto errout; + } + INIT_WORK(&chip->irq_pending_work, azx_irq_pending_work); + if (azx_acquire_irq(chip, 0) < 0) { err = -EBUSY; goto errout;
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