[alsa-devel] [PATCH] ALSA: hda: Use loop counter for hdac_wait_for_cmd_dmas() timeout

[Vinod Koul]

On Thu, May 04, 2017 at 12:25:26PM +0200, Takashi Iwai wrote:
> On Thu, 04 May 2017 12:18:29 +0200,
> Chris Wilson wrote:
> > 
> > hdac_wait_for_cmd_dmas() uses a jiffie timeout to ensure that we do not
> > wait forever for stuck hardware. However, it is called from an
> > irq-disabled context which prevents jiffie from advancing and so the
> > loop doesn't terminate if the hardware fails. This can then cause NMI
> > watchdog warnings, such as:
> > 
> >     NMI watchdog: Watchdog detected hard LOCKUP on cpu 3
> >     Modules linked in: snd_hda_intel i915 vgem snd_hda_codec_hdmi x86_pkg_temp_thermal intel_powerclamp coretemp crct10dif_pclmul crc32_pclmul snd_hda_codec_realtek snd_hda_codec_generic ghash_clmulni_intel e1000e snd_hda_codec snd_hwdep snd_hda_core snd_pcm ptp mei_me prime_numbers pps_core mei lpc_ich i2c_hid i2c_designware_platform i2c_designware_core [last unloaded: i915]
> >     irq event stamp: 13366
> >     hardirqs last  enabled at (13365): [<ffffffff81891a87>] _raw_spin_unlock_irq+0x27/0x50
> >     hardirqs last disabled at (13366): [<ffffffff818918d2>] _raw_spin_lock_irq+0x12/0x50
> >     softirqs last  enabled at (12744): [<ffffffff81085c79>] __do_softirq+0x1d9/0x4c0
> >     softirqs last disabled at (12721): [<ffffffff810860d9>] irq_exit+0xa9/0xc0
> >     CPU: 3 PID: 10443 Comm: kworker/u8:11 Tainted: G     U          4.11.0-rc4-CI-CI_DRM_319+ #1
> >     Hardware name:                  /NUC5i5RYB, BIOS RYBDWi35.86A.0362.2017.0118.0940 01/18/2017
> >     Workqueue: events_unbound async_run_entry_fn
> >     task: ffff88024cd32740 task.stack: ffffc9000162c000
> >     RIP: 0010:preempt_count_add+0xe/0xc0
> >     RSP: 0018:ffffc9000162fbd8 EFLAGS: 00000082
> >     RAX: 0000000080000001 RBX: 0000000704b96558 RCX: 0000000000000002
> >     RDX: 0000000000000000 RSI: ffffffff81c74f2d RDI: 0000000000000001
> >     RBP: ffffc9000162fc08 R08: 00000000bbcc90cc R09: 23c7b07100000000
> >     R10: ffffffff827901a8 R11: ffff88024cd32740 R12: 0000000704b92baa
> >     R13: 0000000000003ea0 R14: 0000000000000003 R15: ffffffffa00061f0
> >     FS:  0000000000000000(0000) GS:ffff880256d80000(0000) knlGS:0000000000000000
> >     CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> >     CR2: 00007f90f84a5144 CR3: 0000000003e0f000 CR4: 00000000003406e0
> >     Call Trace:
> >      ? delay_tsc+0x3d/0xc0
> >      __delay+0xa/0x10
> >      __const_udelay+0x31/0x40
> >      snd_hdac_bus_stop_cmd_io+0x96/0xe0 [snd_hda_core]
> >      ? azx_dev_disconnect+0x20/0x20 [snd_hda_intel]
> >      snd_hdac_bus_stop_chip+0xb1/0x100 [snd_hda_core]
> >      azx_stop_chip+0x9/0x10 [snd_hda_codec]
> >      azx_suspend+0x72/0x220 [snd_hda_intel]
> >      pci_pm_suspend+0x71/0x140
> >      dpm_run_callback+0x6f/0x330
> >      ? pci_pm_freeze+0xe0/0xe0
> >      __device_suspend+0xf9/0x370
> >      ? dpm_watchdog_set+0x60/0x60
> >      async_suspend+0x1a/0x90
> >      async_run_entry_fn+0x34/0x160
> >      process_one_work+0x1f4/0x6d0
> >      ? process_one_work+0x16e/0x6d0
> >      worker_thread+0x49/0x4a0
> >      kthread+0x107/0x140
> >      ? process_one_work+0x6d0/0x6d0
> >      ? kthread_create_on_node+0x40/0x40
> >      ret_from_fork+0x2e/0x40
> > 
> > Fixes: 38b19ed7f81e ("ALSA: hda: fix to wait for RIRB & CORB DMA to set")
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=100419
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Jeeja KP <jeeja.kp at intel.com>
> > Cc: Vinod Koul <vinod.koul at intel.com>
> > Cc: Takashi Iwai <tiwai at suse.de>
> > Cc: <stable at vger.kernel.org> # v4.7+
> 
> Any reason to submit a different fix from what's attached in the
> bugzilla you mentioned?

probably a race between then :)

Jeeja talked to me earlier today and uploaded the patch where we drop the
locks and still use jiffies.

Takashi,
Do you prefer dropping locks or using loop?

> > ---
> >  sound/hda/hdac_controller.c | 8 ++++----
> >  1 file changed, 4 insertions(+), 4 deletions(-)
> > 
> > diff --git a/sound/hda/hdac_controller.c b/sound/hda/hdac_controller.c
> > index ee08c389b4d6..7f8806b03982 100644
> > --- a/sound/hda/hdac_controller.c
> > +++ b/sound/hda/hdac_controller.c
> > @@ -85,14 +85,14 @@ static void hdac_wait_for_cmd_dmas(struct hdac_bus *bus)
> >  {
> >  	unsigned long timeout;
> >  
> > -	timeout = jiffies + msecs_to_jiffies(100);
> > +	timeout = 100 * 100; /* 100ms */
> >  	while ((snd_hdac_chip_readb(bus, RIRBCTL) & AZX_RBCTL_DMA_EN)
> > -		&& time_before(jiffies, timeout))
> > +	       && timeout--)
> >  		udelay(10);
> >  
> > -	timeout = jiffies + msecs_to_jiffies(100);
> > +	timeout = 100 * 100; /* 100ms */
> >  	while ((snd_hdac_chip_readb(bus, CORBCTL) & AZX_CORBCTL_RUN)
> > -		&& time_before(jiffies, timeout))
> > +	       && timeout--)
> >  		udelay(10);
> >  }
> >  
> > -- 
> > 2.11.0
> > 

-- 
~Vinod