sys: Remove BKL from sys_reboot

Serialization of sys_reboot can be done local. The BKL is not
protecting anything else.

LKML-Reference: <20091010153349.405590702@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/kernel/sys.c b/kernel/sys.c
index 255475d163e0cdb62602306a28134d67005e87c0..22ea9553c3bcba4d29dbee52ebc5ca8acc316628 100644 (file)
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -8,7 +8,6 @@
 #include <linux/mm.h>
 #include <linux/utsname.h>
 #include <linux/mman.h>
-#include <linux/smp_lock.h>
 #include <linux/notifier.h>
 #include <linux/reboot.h>
 #include <linux/prctl.h>
@@ -349,6 +348,9 @@ void kernel_power_off(void)
        machine_power_off();
 }
 EXPORT_SYMBOL_GPL(kernel_power_off);
+
+static DEFINE_MUTEX(reboot_mutex);
+
 /*
  * Reboot system call: for obvious reasons only root may call it,
  * and even root needs to set up some magic numbers in the registers
@@ -381,7 +383,7 @@ SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
        if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !pm_power_off)
                cmd = LINUX_REBOOT_CMD_HALT;
 
-       lock_kernel();
+       mutex_lock(&reboot_mutex);
        switch (cmd) {
        case LINUX_REBOOT_CMD_RESTART:
                kernel_restart(NULL);
@@ -397,20 +399,18 @@ SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
 
        case LINUX_REBOOT_CMD_HALT:
                kernel_halt();
-               unlock_kernel();
                do_exit(0);
                panic("cannot halt");
 
        case LINUX_REBOOT_CMD_POWER_OFF:
                kernel_power_off();
-               unlock_kernel();
                do_exit(0);
                break;
 
        case LINUX_REBOOT_CMD_RESTART2:
                if (strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1) < 0) {
-                       unlock_kernel();
-                       return -EFAULT;
+                       ret = -EFAULT;
+                       break;
                }
                buffer[sizeof(buffer) - 1] = '\0';
 
@@ -433,7 +433,7 @@ SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
                ret = -EINVAL;
                break;
        }
-       unlock_kernel();
+       mutex_unlock(&reboot_mutex);
        return ret;
 }