Add common orderly_poweroff()

Various pieces of code around the kernel want to be able to trigger an
orderly poweroff.  This pulls them together into a single
implementation.

By default the poweroff command is /sbin/poweroff, but it can be set
via sysctl: kernel/poweroff_cmd.  This is split at whitespace, so it
can include command-line arguments.

This patch replaces four other instances of invoking either "poweroff"
or "shutdown -h now": two sbus drivers, and acpi thermal
management.

sparc64 has its own "powerd"; still need to determine whether it should
be replaced by orderly_poweroff().

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Acked-by: Len Brown <lenb@kernel.org>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David S. Miller <davem@davemloft.net>

6 files changed, 79 insertions, 30 deletions

diff --git a/drivers/acpi/thermal.c b/drivers/acpi/thermal.c
index 88a6fc7fd271..58f1338981bc 100644
--- a/drivers/acpi/thermal.c
+++ b/drivers/acpi/thermal.c
@@ -40,6 +40,7 @@
 #include <linux/jiffies.h>
 #include <linux/kmod.h>
 #include <linux/seq_file.h>
+#include <linux/reboot.h>
 #include <asm/uaccess.h>
 
 #include <acpi/acpi_bus.h>
@@ -59,7 +60,6 @@
 #define ACPI_THERMAL_NOTIFY_CRITICAL    0xF0
 #define ACPI_THERMAL_NOTIFY_HOT         0xF1
 #define ACPI_THERMAL_MODE_ACTIVE        0x00
-#define ACPI_THERMAL_PATH_POWEROFF      "/sbin/poweroff"
 
 #define ACPI_THERMAL_MAX_ACTIVE 10
 #define ACPI_THERMAL_MAX_LIMIT_STR_LEN 65
@@ -419,26 +419,6 @@ static int acpi_thermal_get_devices(struct acpi_thermal *tz)
         return 0;
 }
 
-static int acpi_thermal_call_usermode(char *path)
-{
-        char *argv[2] = { NULL, NULL };
-        char *envp[3] = { NULL, NULL, NULL };
-
-
-        if (!path)
-                return -EINVAL;
-
-        argv[0] = path;
-
-        /* minimal command environment */
-        envp[0] = "HOME=/";
-        envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
-
-        call_usermodehelper(argv[0], argv, envp, 0);
-
-        return 0;
-}
-
 static int acpi_thermal_critical(struct acpi_thermal *tz)
 {
         if (!tz || !tz->trips.critical.flags.valid)
@@ -456,7 +436,7 @@ static int acpi_thermal_critical(struct acpi_thermal *tz)
         acpi_bus_generate_event(tz->device, ACPI_THERMAL_NOTIFY_CRITICAL,
                                 tz->trips.critical.flags.enabled);
 
-        acpi_thermal_call_usermode(ACPI_THERMAL_PATH_POWEROFF);
+        orderly_poweroff(true);
 
         return 0;
 }
diff --git a/drivers/sbus/char/bbc_envctrl.c b/drivers/sbus/char/bbc_envctrl.c
index a54e4140683a..e821a155b658 100644
--- a/drivers/sbus/char/bbc_envctrl.c
+++ b/drivers/sbus/char/bbc_envctrl.c
@@ -7,6 +7,7 @@
 #include <linux/kthread.h>
 #include <linux/delay.h>
 #include <linux/kmod.h>
+#include <linux/reboot.h>
 #include <asm/oplib.h>
 #include <asm/ebus.h>
 
@@ -170,8 +171,6 @@ static void get_current_temps(struct bbc_cpu_temperature *tp)
 static void do_envctrl_shutdown(struct bbc_cpu_temperature *tp)
 {
         static int shutting_down = 0;
-        static char *envp[] = { "HOME=/", "TERM=linux", "PATH=/sbin:/usr/sbin:/bin:/usr/bin", NULL };
-        char *argv[] = { "/sbin/shutdown", "-h", "now", NULL };
         char *type = "???";
         s8 val = -1;
 
@@ -195,7 +194,7 @@ static void do_envctrl_shutdown(struct bbc_cpu_temperature *tp)
         printk(KERN_CRIT "kenvctrld: Shutting down the system now.\n");
 
         shutting_down = 1;
-        if (call_usermodehelper("/sbin/shutdown", argv, envp, 0) < 0)
+        if (orderly_poweroff(true) < 0)
                 printk(KERN_CRIT "envctrl: shutdown execution failed\n");
 }
 
diff --git a/drivers/sbus/char/envctrl.c b/drivers/sbus/char/envctrl.c
index 8328acab47fd..dadabef116b6 100644
--- a/drivers/sbus/char/envctrl.c
+++ b/drivers/sbus/char/envctrl.c
@@ -26,6 +26,7 @@
 #include <linux/ioport.h>
 #include <linux/miscdevice.h>
 #include <linux/kmod.h>
+#include <linux/reboot.h>
 
 #include <asm/ebus.h>
 #include <asm/uaccess.h>
@@ -966,10 +967,6 @@ static struct i2c_child_t *envctrl_get_i2c_child(unsigned char mon_type)
 static void envctrl_do_shutdown(void)
 {
         static int inprog = 0;
-        static char *envp[] = { 
-                "HOME=/", "TERM=linux", "PATH=/sbin:/usr/sbin:/bin:/usr/bin", NULL };
-        char *argv[] = { 
-                "/sbin/shutdown", "-h", "now", NULL };  
         int ret;
 
         if (inprog != 0)
@@ -977,7 +974,7 @@ static void envctrl_do_shutdown(void)
 
         inprog = 1;
         printk(KERN_CRIT "kenvctrld: WARNING: Shutting down the system now.\n");
-        ret = call_usermodehelper("/sbin/shutdown", argv, envp, 0);
+        ret = orderly_poweroff(true);
         if (ret < 0) {
                 printk(KERN_CRIT "kenvctrld: WARNING: system shutdown failed!\n"); 
                 inprog = 0;  /* unlikely to succeed, but we could try again */
diff --git a/include/linux/reboot.h b/include/linux/reboot.h
index 1dd1c707311f..85ea63f462af 100644
--- a/include/linux/reboot.h
+++ b/include/linux/reboot.h
@@ -67,6 +67,11 @@ extern void kernel_power_off(void);
 
 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);
+
 /*
  * Emergency restart, callable from an interrupt handler.
  */
diff --git a/kernel/sys.c b/kernel/sys.c
index 4d141ae3e802..aeded9ad66ce 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2286,3 +2286,61 @@ asmlinkage long sys_getcpu(unsigned __user *cpup, unsigned __user *nodep,
         }
         return err ? -EFAULT : 0;
 }
+
+char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
+
+static void argv_cleanup(char **argv, char **envp)
+{
+        argv_free(argv);
+}
+
+/**
+ * orderly_poweroff - Trigger an orderly system poweroff
+ * @force: force poweroff if command execution fails
+ *
+ * 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)
+{
+        int argc;
+        char **argv = argv_split(GFP_ATOMIC, poweroff_cmd, &argc);
+        static char *envp[] = {
+                "HOME=/",
+                "PATH=/sbin:/bin:/usr/sbin:/usr/bin",
+                NULL
+        };
+        int ret = -ENOMEM;
+        struct subprocess_info *info;
+
+        if (argv == NULL) {
+                printk(KERN_WARNING "%s failed to allocate memory for \"%s\"\n",
+                       __func__, poweroff_cmd);
+                goto out;
+        }
+
+        info = call_usermodehelper_setup(argv[0], argv, envp);
+        if (info == NULL) {
+                argv_free(argv);
+                goto out;
+        }
+
+        call_usermodehelper_setcleanup(info, argv_cleanup);
+
+        ret = call_usermodehelper_exec(info, -1);
+
+  out:
+        if (ret && force) {
+                printk(KERN_WARNING "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 emergency shutdown? */
+                emergency_sync();
+                kernel_power_off();
+        }
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(orderly_poweroff);
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 7063ebc6db05..44a1d699aad7 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -46,6 +46,7 @@
 #include <linux/syscalls.h>
 #include <linux/nfs_fs.h>
 #include <linux/acpi.h>
+#include <linux/reboot.h>
 
 #include <asm/uaccess.h>
 #include <asm/processor.h>
@@ -705,6 +706,15 @@ static ctl_table kern_table[] = {
                 .proc_handler   = &proc_dointvec,
         },
 #endif
+        {
+                .ctl_name       = CTL_UNNUMBERED,
+                .procname       = "poweroff_cmd",
+                .data           = &poweroff_cmd,
+                .maxlen         = POWEROFF_CMD_PATH_LEN,
+                .mode           = 0644,
+                .proc_handler   = &proc_dostring,
+                .strategy       = &sysctl_string,
+        },
 
         { .ctl_name = 0 }
 };