[PATCH v8 3/3] ASoC: SOF: Fix deadlock when shutdown a frozen userspace

[Ricardo Ribalda]

If we are shutting down due to kexec and the userspace is frozen, the
system will stall forever waiting for userspace to complete.

Do not wait for the clients to complete in that case.

This fixes:

[   84.943749] Freezing user space processes ... (elapsed 0.111 seconds) done.
[  246.784446] INFO: task kexec-lite:5123 blocked for more than 122 seconds.
[  246.819035] Call Trace:
[  246.821782]  <TASK>
[  246.824186]  __schedule+0x5f9/0x1263
[  246.828231]  schedule+0x87/0xc5
[  246.831779]  snd_card_disconnect_sync+0xb5/0x127
...
[  246.889249]  snd_sof_device_shutdown+0xb4/0x150
[  246.899317]  pci_device_shutdown+0x37/0x61
[  246.903990]  device_shutdown+0x14c/0x1d6
[  246.908391]  kernel_kexec+0x45/0xb9

And:

[  246.893222] INFO: task kexec-lite:4891 blocked for more than 122 seconds.
[  246.927709] Call Trace:
[  246.930461]  <TASK>
[  246.932819]  __schedule+0x5f9/0x1263
[  246.936855]  ? fsnotify_grab_connector+0x5c/0x70
[  246.942045]  schedule+0x87/0xc5
[  246.945567]  schedule_timeout+0x49/0xf3
[  246.949877]  wait_for_completion+0x86/0xe8
[  246.954463]  snd_card_free+0x68/0x89
...
[  247.001080]  platform_device_unregister+0x12/0x35

Cc: stable at vger.kernel.org
Fixes: 83bfc7e793b5 ("ASoC: SOF: core: unregister clients and machine drivers in .shutdown")
Signed-off-by: Ricardo Ribalda <ribalda at chromium.org>
---
 sound/soc/sof/core.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/sound/soc/sof/core.c b/sound/soc/sof/core.c
index 3e6141d03770..9587b6a85103 100644
--- a/sound/soc/sof/core.c
+++ b/sound/soc/sof/core.c
@@ -9,6 +9,8 @@
 //
 
 #include <linux/firmware.h>
+#include <linux/kexec.h>
+#include <linux/freezer.h>
 #include <linux/module.h>
 #include <sound/soc.h>
 #include <sound/sof.h>
@@ -484,9 +486,10 @@ int snd_sof_device_shutdown(struct device *dev)
 	 * make sure clients and machine driver(s) are unregistered to force
 	 * all userspace devices to be closed prior to the DSP shutdown sequence
 	 */
-	sof_unregister_clients(sdev);
-
-	snd_sof_machine_unregister(sdev, pdata);
+	if (!(kexec_in_progress() && pm_freezing())) {
+		sof_unregister_clients(sdev);
+		snd_sof_machine_unregister(sdev, pdata);
+	}
 
 	if (sdev->fw_state == SOF_FW_BOOT_COMPLETE)
 		return snd_sof_shutdown(sdev);

-- 
2.39.0.rc0.267.gcb52ba06e7-goog-b4-0.11.0-dev-696ae