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Subject[PATCH v2 2/3] kernel/reboot.c: Add orderly_reboot for graceful reboot
Date
The kernel has orderly_poweroff which allows the kernel to initiate a
graceful shutdown of userspace, by running /sbin/poweroff. This adds
orderly_reboot that will cause userspace to shut itself down by calling
/sbin/reboot.

This will be used for shutdown initiated by a system controller on
platforms that do not use ACPI.

orderly_reboot() should be used when the system wants to allow userspace
to gracefully shut itself down. For cases where the system may
imminently catch on fire, the existing emergency_restart() provides an
immediate reboot without involving userspace.

Signed-off-by: Joel Stanley <joel@jms.id.au>
---
V2:
- remove unused return value from orderly_*
- use correct command in orderly_poweroff
- the reboot command will not have a proc knob to control it, so
it can be made const and static

include/linux/reboot.h | 3 ++-
kernel/reboot.c | 53 +++++++++++++++++++++++++++++++++++++++++++++-----
2 files changed, 50 insertions(+), 6 deletions(-)

diff --git a/include/linux/reboot.h b/include/linux/reboot.h
index 48bf152..dc5e3bd 100644
--- a/include/linux/reboot.h
+++ b/include/linux/reboot.h
@@ -67,7 +67,8 @@ void ctrl_alt_del(void);
#define POWEROFF_CMD_PATH_LEN 256
extern char poweroff_cmd[POWEROFF_CMD_PATH_LEN];

-extern int orderly_poweroff(bool force);
+extern void orderly_poweroff(bool force);
+extern void orderly_reboot(void);

/*
* Emergency restart, callable from an interrupt handler.
diff --git a/kernel/reboot.c b/kernel/reboot.c
index a3a9e24..0ace9f6 100644
--- a/kernel/reboot.c
+++ b/kernel/reboot.c
@@ -306,8 +306,9 @@ void ctrl_alt_del(void)
}

char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
+static const char reboot_cmd[] = "/sbin/reboot";

-static int __orderly_poweroff(bool force)
+static int run_cmd(const char *cmd)
{
char **argv;
static char *envp[] = {
@@ -316,8 +317,7 @@ static int __orderly_poweroff(bool force)
NULL
};
int ret;
-
- argv = argv_split(GFP_KERNEL, poweroff_cmd, NULL);
+ argv = argv_split(GFP_KERNEL, cmd, NULL);
if (argv) {
ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
argv_free(argv);
@@ -325,8 +325,33 @@ static int __orderly_poweroff(bool force)
ret = -ENOMEM;
}

+ return ret;
+}
+
+static int __orderly_reboot(void)
+{
+ int ret;
+
+ ret = run_cmd(reboot_cmd);
+
+ if (ret) {
+ pr_warn("Failed to start orderly reboot: forcing the issue\n");
+ emergency_sync();
+ kernel_restart(NULL);
+ }
+
+ return ret;
+}
+
+static int __orderly_poweroff(bool force)
+{
+ int ret;
+
+ ret = run_cmd(poweroff_cmd);
+
if (ret && force) {
pr_warn("Failed to start orderly shutdown: forcing the issue\n");
+
/*
* I guess this should try to kick off some daemon to sync and
* poweroff asap. Or not even bother syncing if we're doing an
@@ -355,15 +380,33 @@ static DECLARE_WORK(poweroff_work, poweroff_work_func);
* This may be called from any context to trigger a system shutdown.
* If the orderly shutdown fails, it will force an immediate shutdown.
*/
-int orderly_poweroff(bool force)
+void orderly_poweroff(bool force)
{
if (force) /* do not override the pending "true" */
poweroff_force = true;
schedule_work(&poweroff_work);
- return 0;
}
EXPORT_SYMBOL_GPL(orderly_poweroff);

+static void reboot_work_func(struct work_struct *work)
+{
+ __orderly_reboot();
+}
+
+static DECLARE_WORK(reboot_work, reboot_work_func);
+
+/**
+ * orderly_reboot - Trigger an orderly system reboot
+ *
+ * This may be called from any context to trigger a system reboot.
+ * If the orderly reboot fails, it will force an immediate reboot.
+ */
+void orderly_reboot(void)
+{
+ schedule_work(&reboot_work);
+}
+EXPORT_SYMBOL_GPL(orderly_reboot);
+
static int __init reboot_setup(char *str)
{
for (;;) {
--
2.1.4


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