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>

2 files changed, 68 insertions, 0 deletions

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 }
 };