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From:   Kai-Heng Feng <kai.heng.feng@canonical.com>
To:     rafael.j.wysocki@intel.com, lenb@kernel.org
Cc:     Kai-Heng Feng <kai.heng.feng@canonical.com>,
        Dmitry Osipenko <dmitry.osipenko@collabora.com>,
        tangmeng <tangmeng@uniontech.com>,
        Luis Chamberlain <mcgrof@kernel.org>,
        Petr Mladek <pmladek@suse.com>,
        YueHaibing <yuehaibing@huawei.com>, linux-kernel@vger.kernel.org
Subject: [PATCH v3 1/2] kernel/reboot: Add SYS_OFF_MODE_RESTART_PREPARE mode
Date:   Tue, 13 Sep 2022 14:20:39 +0800
Message-Id: <20220913062042.1977790-1-kai.heng.feng@canonical.com>
MIME-Version: 1.0
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Add SYS_OFF_MODE_RESTART_PREPARE callbacks can be invoked before system
restart.

This is a preparation for next patch.

Suggested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---
v3:
 - New patch.

 include/linux/reboot.h |  8 ++++++++
 kernel/reboot.c        | 17 +++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/include/linux/reboot.h b/include/linux/reboot.h
index e5d9ef886179c..ba87cdef2335a 100644
--- a/include/linux/reboot.h
+++ b/include/linux/reboot.h
@@ -105,6 +105,14 @@ enum sys_off_mode {
 	 */
 	SYS_OFF_MODE_POWER_OFF,
 
+	/**
+	 * @SYS_OFF_MODE_RESTART_PREPARE:
+	 *
+	 * Handlers prepare system to be powered off. Handlers are
+	 * allowed to sleep.
+	 */
+	SYS_OFF_MODE_RESTART_PREPARE,
+
 	/**
 	 * @SYS_OFF_MODE_RESTART:
 	 *
diff --git a/kernel/reboot.c b/kernel/reboot.c
index 3c35445bf5ad3..3bba88c7ffc6b 100644
--- a/kernel/reboot.c
+++ b/kernel/reboot.c
@@ -243,6 +243,17 @@ void migrate_to_reboot_cpu(void)
 	set_cpus_allowed_ptr(current, cpumask_of(cpu));
 }
 
+/*
+ *	Notifier list for kernel code which wants to be called
+ *	to prepare system for restart.
+ */
+static BLOCKING_NOTIFIER_HEAD(restart_prep_handler_list);
+
+static void do_kernel_restart_prepare(void)
+{
+	blocking_notifier_call_chain(&restart_prep_handler_list, 0, NULL);
+}
+
 /**
  *	kernel_restart - reboot the system
  *	@cmd: pointer to buffer containing command to execute for restart
@@ -254,6 +265,7 @@ void migrate_to_reboot_cpu(void)
 void kernel_restart(char *cmd)
 {
 	kernel_restart_prepare(cmd);
+	do_kernel_restart_prepare();
 	migrate_to_reboot_cpu();
 	syscore_shutdown();
 	if (!cmd)
@@ -396,6 +408,11 @@ register_sys_off_handler(enum sys_off_mode mode,
 		handler->list = &power_off_handler_list;
 		break;
 
+	case SYS_OFF_MODE_RESTART_PREPARE:
+		handler->list = &restart_prep_handler_list;
+		handler->blocking = true;
+		break;
+
 	case SYS_OFF_MODE_RESTART:
 		handler->list = &restart_handler_list;
 		break;
-- 
2.36.1