linux-kernel - [PATCH v6 1/2] kexec: Introduce kexec_with_frozen

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Date:   Wed, 30 Nov 2022 16:47:15 +0100
From:   Ricardo Ribalda <ribalda@...omium.org>
To:     Chromeos Kdump <chromeos-kdump@...gle.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Eric Biederman <ebiederm@...ssion.com>,
        Daniel Baluta <daniel.baluta@....com>,
        Mark Brown <broonie@...nel.org>,
        Bard Liao <yung-chuan.liao@...ux.intel.com>,
        Jaroslav Kysela <perex@...ex.cz>,
        Kai Vehmanen <kai.vehmanen@...ux.intel.com>,
        Ranjani Sridharan <ranjani.sridharan@...ux.intel.com>,
        Peter Ujfalusi <peter.ujfalusi@...ux.intel.com>,
        Takashi Iwai <tiwai@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>
Cc:     Ricardo Ribalda <ribalda@...omium.org>, stable@...r.kernel.org,
        linux-kernel@...r.kernel.org, alsa-devel@...a-project.org,
        kexec@...ts.infradead.org, sound-open-firmware@...a-project.org
Subject: [PATCH v6 1/2] kexec: Introduce kexec_with_frozen_processes

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@...omium.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 = {

-- 
2.38.1.584.g0f3c55d4c2-goog-b4-0.11.0-dev-696ae