1 files changed, 15 insertions, 16 deletions

diff --git a/kernel/sys.c b/kernel/sys.c
index 9968c5fb55b9..877fe4f8e05e 100644
--- 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>
@@ -163,6 +162,7 @@ SYSCALL_DEFINE3(setpriority, int, which, int, who, int, niceval)
         if (niceval > 19)
                 niceval = 19;
 
+        rcu_read_lock();
         read_lock(&tasklist_lock);
         switch (which) {
                 case PRIO_PROCESS:
@@ -190,16 +190,17 @@ SYSCALL_DEFINE3(setpriority, int, which, int, who, int, niceval)
                                  !(user = find_user(who)))
                                 goto out_unlock;        /* No processes for this user */
 
-                        do_each_thread(g, p)
+                        do_each_thread(g, p) {
                                 if (__task_cred(p)->uid == who)
                                         error = set_one_prio(p, niceval, error);
-                        while_each_thread(g, p);
+                        } while_each_thread(g, p);
                         if (who != cred->uid)
                                 free_uid(user);         /* For find_user() */
                         break;
         }
 out_unlock:
         read_unlock(&tasklist_lock);
+        rcu_read_unlock();
 out:
         return error;
 }
@@ -221,6 +222,7 @@ SYSCALL_DEFINE2(getpriority, int, which, int, who)
         if (which > PRIO_USER || which < PRIO_PROCESS)
                 return -EINVAL;
 
+        rcu_read_lock();
         read_lock(&tasklist_lock);
         switch (which) {
                 case PRIO_PROCESS:
@@ -253,19 +255,20 @@ SYSCALL_DEFINE2(getpriority, int, which, int, who)
                                  !(user = find_user(who)))
                                 goto out_unlock;        /* No processes for this user */
 
-                        do_each_thread(g, p)
+                        do_each_thread(g, p) {
                                 if (__task_cred(p)->uid == who) {
                                         niceval = 20 - task_nice(p);
                                         if (niceval > retval)
                                                 retval = niceval;
                                 }
-                        while_each_thread(g, p);
+                        } while_each_thread(g, p);
                         if (who != cred->uid)
                                 free_uid(user);         /* for find_user() */
                         break;
         }
 out_unlock:
         read_unlock(&tasklist_lock);
+        rcu_read_unlock();
 
         return retval;
 }
@@ -349,6 +352,9 @@ 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 +387,7 @@ 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 +403,18 @@ 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 +437,7 @@ SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
                 ret = -EINVAL;
                 break;
         }
-        unlock_kernel();
+        mutex_unlock(&reboot_mutex);
         return ret;
 }
 
@@ -567,11 +571,6 @@ static int set_user(struct cred *new)
         if (!new_user)
                 return -EAGAIN;
 
-        if (!task_can_switch_user(new_user, current)) {
-                free_uid(new_user);
-                return -EINVAL;
-        }
-
         if (atomic_read(&new_user->processes) >=
                                 current->signal->rlim[RLIMIT_NPROC].rlim_cur &&
                         new_user != INIT_USER) {