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Message-ID: <CAJZ5v0jbKSTQopEoXW9FpqDmAqp6Pn=-Om5QP2-7ocuGdq8R9w@mail.gmail.com>
Date: Fri, 2 Dec 2022 18:47:47 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Ricardo Ribalda <ribalda@...omium.org>
Cc: Juergen Gross <jgross@...e.com>, Mark Brown <broonie@...nel.org>,
Chromeos Kdump <chromeos-kdump@...gle.com>,
Daniel Baluta <daniel.baluta@....com>,
Christophe Leroy <christophe.leroy@...roup.eu>,
Len Brown <len.brown@...el.com>,
Ard Biesheuvel <ardb@...nel.org>,
Ranjani Sridharan <ranjani.sridharan@...ux.intel.com>,
"Rafael J. Wysocki" <rafael@...nel.org>,
Boris Ostrovsky <boris.ostrovsky@...cle.com>,
Nicholas Piggin <npiggin@...il.com>,
Michael Ellerman <mpe@...erman.id.au>,
Eric Biederman <ebiederm@...ssion.com>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Jaroslav Kysela <perex@...ex.cz>,
Joel Fernandes <joel@...lfernandes.org>,
Liam Girdwood <lgirdwood@...il.com>,
Peter Ujfalusi <peter.ujfalusi@...ux.intel.com>,
Pavel Machek <pavel@....cz>,
Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
Kai Vehmanen <kai.vehmanen@...ux.intel.com>,
Steven Rostedt <rostedt@...dmis.org>,
"K. Y. Srinivasan" <kys@...rosoft.com>,
Ingo Molnar <mingo@...hat.com>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Dexuan Cui <decui@...rosoft.com>,
Takashi Iwai <tiwai@...e.com>,
"H. Peter Anvin" <hpa@...or.com>,
Bard Liao <yung-chuan.liao@...ux.intel.com>,
Haiyang Zhang <haiyangz@...rosoft.com>,
Wei Liu <wei.liu@...nel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Borislav Petkov <bp@...en8.de>, x86@...nel.org,
kexec@...ts.infradead.org, alsa-devel@...a-project.org,
stable@...r.kernel.org, sound-open-firmware@...a-project.org,
linuxppc-dev@...ts.ozlabs.org, linux-hyperv@...r.kernel.org,
linux-pci@...r.kernel.org, linux-pm@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org,
xen-devel@...ts.xenproject.org
Subject: Re: [PATCH v8 2/3] freezer: refactor pm_freezing into a function.
On Thu, Dec 1, 2022 at 12:08 PM Ricardo Ribalda <ribalda@...omium.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@...r.kernel.org
> Fixes: 83bfc7e793b5 ("ASoC: SOF: core: unregister clients and machine drivers in .shutdown")
> Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
Why can't you export the original pm_freezing variable and why is this
fixing anything?
> ---
> 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();
>
> --
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