[PATCH v6 0/2] ASoC: SOF: Fix deadlock when shutdown a frozen userspace
Since: 83bfc7e793b5 ("ASoC: SOF: core: unregister clients and machine drivers in .shutdown") we wait for all the workloads to be completed during shutdown. This was done to avoid a stall once the device is started again.
Unfortunately this has the side effect of stalling kexec(), if the userspace is frozen. Let's handle that case.
To: Pierre-Louis Bossart pierre-louis.bossart@linux.intel.com To: Liam Girdwood lgirdwood@gmail.com To: Peter Ujfalusi peter.ujfalusi@linux.intel.com To: Bard Liao yung-chuan.liao@linux.intel.com To: Ranjani Sridharan ranjani.sridharan@linux.intel.com To: Kai Vehmanen kai.vehmanen@linux.intel.com To: Daniel Baluta daniel.baluta@nxp.com To: Mark Brown broonie@kernel.org To: Jaroslav Kysela perex@perex.cz To: Takashi Iwai tiwai@suse.com To: Eric Biederman ebiederm@xmission.com To: Chromeos Kdump chromeos-kdump@google.com To: Steven Rostedt rostedt@goodmis.org Cc: stable@vger.kernel.org Cc: sound-open-firmware@alsa-project.org Cc: alsa-devel@alsa-project.org Cc: linux-kernel@vger.kernel.org Cc: kexec@lists.infradead.org Signed-off-by: Ricardo Ribalda ribalda@chromium.org --- Changes in v6: - Check if we are in kexec with the userspace frozen. - Link to v5: https://lore.kernel.org/r/20221127-snd-freeze-v5-0-4ededeb08ba0@chromium.org
Changes in v5: - Edit subject prefix. - Link to v4: https://lore.kernel.org/r/20221127-snd-freeze-v4-0-51ca64b7f2ab@chromium.org
Changes in v4: - Do not call snd_sof_machine_unregister from shutdown. - Link to v3: https://lore.kernel.org/r/20221127-snd-freeze-v3-0-a2eda731ca14@chromium.org
Changes in v3: - Wrap pm_freezing in a function. - Link to v2: https://lore.kernel.org/r/20221127-snd-freeze-v2-0-d8a425ea9663@chromium.org
Changes in v2: - Only use pm_freezing if CONFIG_FREEZER . - Link to v1: https://lore.kernel.org/r/20221127-snd-freeze-v1-0-57461a366ec2@chromium.org
--- Ricardo Ribalda (2): kexec: Introduce kexec_with_frozen_processes ASoC: SOF: Fix deadlock when shutdown a frozen userspace
include/linux/kexec.h | 3 +++ kernel/kexec_core.c | 5 +++++ sound/soc/sof/core.c | 4 +++- 3 files changed, 11 insertions(+), 1 deletion(-) --- base-commit: 4312098baf37ee17a8350725e6e0d0e8590252d4 change-id: 20221127-snd-freeze-1ee143228326
Best regards,
Drivers running .shutdown() might want to wait for userspace to complete before exiting.
If userspace is frozen and we are running kexec they will stall the computer.
Add a way for them to figure out if they should just skip waiting for userspace.
Signed-off-by: Ricardo Ribalda ribalda@chromium.org --- include/linux/kexec.h | 3 +++ kernel/kexec_core.c | 5 +++++ 2 files changed, 8 insertions(+)
diff --git a/include/linux/kexec.h b/include/linux/kexec.h index 41a686996aaa..c22711e0f7b5 100644 --- a/include/linux/kexec.h +++ b/include/linux/kexec.h @@ -426,6 +426,8 @@ extern int kexec_load_disabled; /* flag to track if kexec reboot is in progress */ extern bool kexec_in_progress;
+bool kexec_with_frozen_processes(void); + int crash_shrink_memory(unsigned long new_size); ssize_t crash_get_memory_size(void);
@@ -507,6 +509,7 @@ static inline void __crash_kexec(struct pt_regs *regs) { } static inline void crash_kexec(struct pt_regs *regs) { } static inline int kexec_should_crash(struct task_struct *p) { return 0; } static inline int kexec_crash_loaded(void) { return 0; } +static inline bool kexec_with_frozen_processes(void) { return false; } #define kexec_in_progress false #endif /* CONFIG_KEXEC_CORE */
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c index ca2743f9c634..8bc8257ee7ca 100644 --- a/kernel/kexec_core.c +++ b/kernel/kexec_core.c @@ -54,6 +54,11 @@ note_buf_t __percpu *crash_notes; /* Flag to indicate we are going to kexec a new kernel */ bool kexec_in_progress = false;
+bool kexec_with_frozen_processes(void) +{ + return kexec_in_progress && pm_freezing; +} +EXPORT_SYMBOL(kexec_with_frozen_processes);
/* Location of the reserved area for the crash kernel */ struct resource crashk_res = {
During kexec(), the userspace is frozen. Therefore we cannot wait for it to complete.
Avoid running snd_sof_machine_unregister during shutdown.
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@vger.kernel.org Fixes: 83bfc7e793b5 ("ASoC: SOF: core: unregister clients and machine drivers in .shutdown") Signed-off-by: Ricardo Ribalda ribalda@chromium.org --- sound/soc/sof/core.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/sound/soc/sof/core.c b/sound/soc/sof/core.c index 3e6141d03770..4301f347bb90 100644 --- a/sound/soc/sof/core.c +++ b/sound/soc/sof/core.c @@ -9,6 +9,7 @@ //
#include <linux/firmware.h> +#include <linux/kexec.h> #include <linux/module.h> #include <sound/soc.h> #include <sound/sof.h> @@ -484,7 +485,8 @@ 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); + if (!kexec_with_frozen_processes()) + sof_unregister_clients(sdev);
snd_sof_machine_unregister(sdev, pdata);
On 11/30/22 09:47, Ricardo Ribalda wrote:
During kexec(), the userspace is frozen. Therefore we cannot wait for it to complete.
Avoid running snd_sof_machine_unregister during shutdown.
That's not what you are doing below - you only unregister clients conditionally.
I don't know if that's a stale commit message and can't reconcile it either with the initial discussions in this thread where we were referring to snd_card_disconnect(), etc?
Confused.
@@ -484,7 +485,8 @@ 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);
if (!kexec_with_frozen_processes())
sof_unregister_clients(sdev);snd_sof_machine_unregister(sdev, pdata);
participants (2)
-
Pierre-Louis Bossart -
Ricardo Ribalda