[alsa-devel] [PATCH] ALSA: hda: Fix cpu lockup when stopping the cmd dmas

[jeeja.kp at intel.com]

From: Jeeja KP <jeeja.kp at intel.com>

Using jiffies in hdac_wait_for_cmd_dmas() to determine when to time out
when interrupts are off (snd_hdac_bus_stop_cmd_io()/spin_lock_irq())
causes hard lockup so unlock while waiting using jiffies.

---<-snip->---
<0>[ 1211.603046] NMI watchdog: Watchdog detected hard LOCKUP on cpu 3
<4>[ 1211.603047] Modules linked in: snd_hda_intel i915 vgem
<4>[ 1211.603053] irq event stamp: 13366
<4>[ 1211.603053] hardirqs last  enabled at (13365):
...
<4>[ 1211.603059] Call Trace:
<4>[ 1211.603059]  ? delay_tsc+0x3d/0xc0
<4>[ 1211.603059]  __delay+0xa/0x10
<4>[ 1211.603060]  __const_udelay+0x31/0x40
<4>[ 1211.603060]  snd_hdac_bus_stop_cmd_io+0x96/0xe0 [snd_hda_core]
<4>[ 1211.603060]  ? azx_dev_disconnect+0x20/0x20 [snd_hda_intel]
<4>[ 1211.603061]  snd_hdac_bus_stop_chip+0xb1/0x100 [snd_hda_core]
<4>[ 1211.603061]  azx_stop_chip+0x9/0x10 [snd_hda_codec]
<4>[ 1211.603061]  azx_suspend+0x72/0x220 [snd_hda_intel]
<4>[ 1211.603061]  pci_pm_suspend+0x71/0x140
<4>[ 1211.603062]  dpm_run_callback+0x6f/0x330
<4>[ 1211.603062]  ? pci_pm_freeze+0xe0/0xe0
<4>[ 1211.603062]  __device_suspend+0xf9/0x370
<4>[ 1211.603062]  ? dpm_watchdog_set+0x60/0x60
<4>[ 1211.603063]  async_suspend+0x1a/0x90
<4>[ 1211.603063]  async_run_entry_fn+0x34/0x160
<4>[ 1211.603063]  process_one_work+0x1f4/0x6d0
<4>[ 1211.603063]  ? process_one_work+0x16e/0x6d0
<4>[ 1211.603064]  worker_thread+0x49/0x4a0
<4>[ 1211.603064]  kthread+0x107/0x140
<4>[ 1211.603064]  ? process_one_work+0x6d0/0x6d0
<4>[ 1211.603065]  ? kthread_create_on_node+0x40/0x40
<4>[ 1211.603065]  ret_from_fork+0x2e/0x40

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=100419
Reported-by: Marta Lofstedt <marta.lofstedt at intel.com>
Suggested-by: Takashi Iwai <tiwai at suse.de>
Signed-off-by: Jeeja KP <jeeja.kp at intel.com>
---
 sound/hda/hdac_controller.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/sound/hda/hdac_controller.c b/sound/hda/hdac_controller.c
index 6f1e99c..0f703372 100644
--- a/sound/hda/hdac_controller.c
+++ b/sound/hda/hdac_controller.c
@@ -106,7 +106,11 @@ void snd_hdac_bus_stop_cmd_io(struct hdac_bus *bus)
 	/* disable ringbuffer DMAs */
 	snd_hdac_chip_writeb(bus, RIRBCTL, 0);
 	snd_hdac_chip_writeb(bus, CORBCTL, 0);
+	spin_unlock_irq(&bus->reg_lock);
+
 	hdac_wait_for_cmd_dmas(bus);
+
+	spin_lock_irq(&bus->reg_lock);
 	/* disable unsolicited responses */
 	snd_hdac_chip_updatel(bus, GCTL, AZX_GCTL_UNSOL, 0);
 	spin_unlock_irq(&bus->reg_lock);
-- 
2.5.0