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December 2022

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Re: [Sound-open-firmware] [PATCH v8 2/3] freezer: refactor pm_freezing into a function.
by Ricardo Ribalda 05 Dec '22

05 Dec '22

Hi Rafael On Fri, 2 Dec 2022 at 18:48, Rafael J. Wysocki <rafael(a)kernel.org> wrote: > > On Thu, Dec 1, 2022 at 12:08 PM Ricardo Ribalda <ribalda(a)chromium.org> wrote: > > > > Add a way to let the drivers know if the processes are frozen. > > > > This is needed by drivers that are waiting for processes to end on their > > shutdown path. > > > > Convert pm_freezing into a function and export it, so it can be used by > > drivers that are either built-in or modules. > > > > Cc: stable(a)vger.kernel.org > > Fixes: 83bfc7e793b5 ("ASoC: SOF: core: unregister clients and machine drivers in .shutdown") > > Signed-off-by: Ricardo Ribalda <ribalda(a)chromium.org> > > Why can't you export the original pm_freezing variable and why is this > fixing anything? Because then any module will be able to modify the content of the variable. The Fixes: is because the last patch on the set is doing a real fix. If you only cherry-pick the last patch on a stable branch, the build will fail. (Also, the zero-day builder complains) Anyway, I think we can hold this patch for a bit. The snd people are discussing if this the way to handle it, or if we should handle .shutdown in a different way. Thanks! > > > --- > > include/linux/freezer.h | 3 ++- > > kernel/freezer.c | 3 +-- > > kernel/power/process.c | 24 ++++++++++++++++++++---- > > 3 files changed, 23 insertions(+), 7 deletions(-) > > > > diff --git a/include/linux/freezer.h b/include/linux/freezer.h > > index b303472255be..3413c869d68b 100644 > > --- a/include/linux/freezer.h > > +++ b/include/linux/freezer.h > > @@ -13,7 +13,7 @@ > > #ifdef CONFIG_FREEZER > > DECLARE_STATIC_KEY_FALSE(freezer_active); > > > > -extern bool pm_freezing; /* PM freezing in effect */ > > +bool pm_freezing(void); > > extern bool pm_nosig_freezing; /* PM nosig freezing in effect */ > > > > /* > > @@ -80,6 +80,7 @@ static inline int freeze_processes(void) { return -ENOSYS; } > > static inline int freeze_kernel_threads(void) { return -ENOSYS; } > > static inline void thaw_processes(void) {} > > static inline void thaw_kernel_threads(void) {} > > +static inline bool pm_freezing(void) { return false; } > > > > static inline bool try_to_freeze(void) { return false; } > > > > diff --git a/kernel/freezer.c b/kernel/freezer.c > > index 4fad0e6fca64..2d3530ebdb7e 100644 > > --- a/kernel/freezer.c > > +++ b/kernel/freezer.c > > @@ -20,7 +20,6 @@ EXPORT_SYMBOL(freezer_active); > > * indicate whether PM freezing is in effect, protected by > > * system_transition_mutex > > */ > > -bool pm_freezing; > > bool pm_nosig_freezing; > > > > /* protects freezing and frozen transitions */ > > @@ -46,7 +45,7 @@ bool freezing_slow_path(struct task_struct *p) > > if (pm_nosig_freezing || cgroup_freezing(p)) > > return true; > > > > - if (pm_freezing && !(p->flags & PF_KTHREAD)) > > + if (pm_freezing() && !(p->flags & PF_KTHREAD)) > > return true; > > > > return false; > > diff --git a/kernel/power/process.c b/kernel/power/process.c > > index ddd9988327fe..8a4d0e2c8c20 100644 > > --- a/kernel/power/process.c > > +++ b/kernel/power/process.c > > @@ -108,6 +108,22 @@ static int try_to_freeze_tasks(bool user_only) > > return todo ? -EBUSY : 0; > > } > > > > +/* > > + * Indicate whether PM freezing is in effect, protected by > > + * system_transition_mutex. > > + */ > > +static bool pm_freezing_internal; > > + > > +/** > > + * pm_freezing - indicate whether PM freezing is in effect. > > + * > > + */ > > +bool pm_freezing(void) > > +{ > > + return pm_freezing_internal; > > +} > > +EXPORT_SYMBOL(pm_freezing); > > Use EXPORT_SYMBOL_GPL() instead, please. > > > + > > /** > > * freeze_processes - Signal user space processes to enter the refrigerator. > > * The current thread will not be frozen. The same process that calls > > @@ -126,12 +142,12 @@ int freeze_processes(void) > > /* Make sure this task doesn't get frozen */ > > current->flags |= PF_SUSPEND_TASK; > > > > - if (!pm_freezing) > > + if (!pm_freezing()) > > static_branch_inc(&freezer_active); > > > > pm_wakeup_clear(0); > > pr_info("Freezing user space processes ... "); > > - pm_freezing = true; > > + pm_freezing_internal = true; > > error = try_to_freeze_tasks(true); > > if (!error) { > > __usermodehelper_set_disable_depth(UMH_DISABLED); > > @@ -187,9 +203,9 @@ void thaw_processes(void) > > struct task_struct *curr = current; > > > > trace_suspend_resume(TPS("thaw_processes"), 0, true); > > - if (pm_freezing) > > + if (pm_freezing()) > > static_branch_dec(&freezer_active); > > - pm_freezing = false; > > + pm_freezing_internal = false; > > pm_nosig_freezing = false; > > > > oom_killer_enable(); > > > > -- > > -- > You received this message because you are subscribed to the Google Groups "Chromeos Kdump" group. > To unsubscribe from this group and stop receiving emails from it, send an email to chromeos-kdump+unsubscribe(a)google.com. > To view this discussion on the web, visit https://groups.google.com/a/google.com/d/msgid/chromeos-kdump/CAJZ5v0jbKSTQ…. -- Ricardo Ribalda

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[Sound-open-firmware] [PATCH v7 0/2] ASoC: SOF: Fix deadlock when shutdown a frozen userspace
by Ricardo Ribalda 01 Dec '22

01 Dec '22

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(a)linux.intel.com> To: Liam Girdwood <lgirdwood(a)gmail.com> To: Peter Ujfalusi <peter.ujfalusi(a)linux.intel.com> To: Bard Liao <yung-chuan.liao(a)linux.intel.com> To: Ranjani Sridharan <ranjani.sridharan(a)linux.intel.com> To: Kai Vehmanen <kai.vehmanen(a)linux.intel.com> To: Daniel Baluta <daniel.baluta(a)nxp.com> To: Mark Brown <broonie(a)kernel.org> To: Jaroslav Kysela <perex(a)perex.cz> To: Takashi Iwai <tiwai(a)suse.com> To: Eric Biederman <ebiederm(a)xmission.com> To: Chromeos Kdump <chromeos-kdump(a)google.com> To: Steven Rostedt <rostedt(a)goodmis.org> Cc: stable(a)vger.kernel.org Cc: sound-open-firmware(a)alsa-project.org Cc: alsa-devel(a)alsa-project.org Cc: linux-kernel(a)vger.kernel.org Cc: kexec(a)lists.infradead.org Signed-off-by: Ricardo Ribalda <ribalda(a)chromium.org> --- Changes in v7: - Fix commit message (Thanks Pierre-Louis). - Link to v6: https://lore.kernel.org/r/20221127-snd-freeze-v6-0-3e90553f64a5@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, -- Ricardo Ribalda <ribalda(a)chromium.org>

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