[Sound-open-firmware] [PATCH v6 0/2] ASoC: SOF: Fix deadlock when shutdown a frozen userspace
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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,
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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 = {
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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);
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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