1 files changed, 41 insertions, 42 deletions

diff --git a/kernel/sys.c b/kernel/sys.c
index 0b6ec0e7936f..e236f98f7ec5 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -4,7 +4,6 @@
  *  Copyright (C) 1991, 1992  Linus Torvalds
  */
 
-#include <linux/config.h>
 #include <linux/module.h>
 #include <linux/mm.h>
 #include <linux/utsname.h>
@@ -13,7 +12,6 @@
 #include <linux/notifier.h>
 #include <linux/reboot.h>
 #include <linux/prctl.h>
-#include <linux/init.h>
 #include <linux/highuid.h>
 #include <linux/fs.h>
 #include <linux/kernel.h>
@@ -57,6 +55,12 @@
 #ifndef GET_FPEXC_CTL
 # define GET_FPEXC_CTL(a,b)     (-EINVAL)
 #endif
+#ifndef GET_ENDIAN
+# define GET_ENDIAN(a,b)        (-EINVAL)
+#endif
+#ifndef SET_ENDIAN
+# define SET_ENDIAN(a,b)        (-EINVAL)
+#endif
 
 /*
  * this is where the system-wide overflow UID and GID are defined, for
@@ -132,14 +136,15 @@ static int __kprobes notifier_call_chain(struct notifier_block **nl,
                 unsigned long val, void *v)
 {
         int ret = NOTIFY_DONE;
-        struct notifier_block *nb;
+        struct notifier_block *nb, *next_nb;
 
         nb = rcu_dereference(*nl);
         while (nb) {
+                next_nb = rcu_dereference(nb->next);
                 ret = nb->notifier_call(nb, val, v);
                 if ((ret & NOTIFY_STOP_MASK) == NOTIFY_STOP_MASK)
                         break;
-                nb = rcu_dereference(nb->next);
+                nb = next_nb;
         }
         return ret;
 }
@@ -583,7 +588,7 @@ void emergency_restart(void)
 }
 EXPORT_SYMBOL_GPL(emergency_restart);
 
-void kernel_restart_prepare(char *cmd)
+static void kernel_restart_prepare(char *cmd)
 {
         blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
         system_state = SYSTEM_RESTART;
@@ -617,7 +622,7 @@ EXPORT_SYMBOL_GPL(kernel_restart);
  *      Move into place and start executing a preloaded standalone
  *      executable.  If nothing was preloaded return an error.
  */
-void kernel_kexec(void)
+static void kernel_kexec(void)
 {
 #ifdef CONFIG_KEXEC
         struct kimage *image;
@@ -631,7 +636,6 @@ void kernel_kexec(void)
         machine_kexec(image);
 #endif
 }
-EXPORT_SYMBOL_GPL(kernel_kexec);
 
 void kernel_shutdown_prepare(enum system_states state)
 {
@@ -1860,23 +1864,20 @@ out:
  * fields when reaping, so a sample either gets all the additions of a
  * given child after it's reaped, or none so this sample is before reaping.
  *
- * tasklist_lock locking optimisation:
- * If we are current and single threaded, we do not need to take the tasklist
- * lock or the siglock.  No one else can take our signal_struct away,
- * no one else can reap the children to update signal->c* counters, and
- * no one else can race with the signal-> fields.
- * If we do not take the tasklist_lock, the signal-> fields could be read
- * out of order while another thread was just exiting. So we place a
- * read memory barrier when we avoid the lock.  On the writer side,
- * write memory barrier is implied in  __exit_signal as __exit_signal releases
- * the siglock spinlock after updating the signal-> fields.
- *
- * We don't really need the siglock when we access the non c* fields
- * of the signal_struct (for RUSAGE_SELF) even in multithreaded
- * case, since we take the tasklist lock for read and the non c* signal->
- * fields are updated only in __exit_signal, which is called with
- * tasklist_lock taken for write, hence these two threads cannot execute
- * concurrently.
+ * Locking:
+ * We need to take the siglock for CHILDEREN, SELF and BOTH
+ * for  the cases current multithreaded, non-current single threaded
+ * non-current multithreaded.  Thread traversal is now safe with
+ * the siglock held.
+ * Strictly speaking, we donot need to take the siglock if we are current and
+ * single threaded,  as no one else can take our signal_struct away, no one
+ * else can  reap the  children to update signal->c* counters, and no one else
+ * can race with the signal-> fields. If we do not take any lock, the
+ * signal-> fields could be read out of order while another thread was just
+ * exiting. So we should  place a read memory barrier when we avoid the lock.
+ * On the writer side,  write memory barrier is implied in  __exit_signal
+ * as __exit_signal releases  the siglock spinlock after updating the signal->
+ * fields. But we don't do this yet to keep things simple.
  *
  */
 
@@ -1885,35 +1886,25 @@ static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
         struct task_struct *t;
         unsigned long flags;
         cputime_t utime, stime;
-        int need_lock = 0;
 
         memset((char *) r, 0, sizeof *r);
         utime = stime = cputime_zero;
 
-        if (p != current || !thread_group_empty(p))
-                need_lock = 1;
-
-        if (need_lock) {
-                read_lock(&tasklist_lock);
-                if (unlikely(!p->signal)) {
-                        read_unlock(&tasklist_lock);
-                        return;
-                }
-        } else
-                /* See locking comments above */
-                smp_rmb();
+        rcu_read_lock();
+        if (!lock_task_sighand(p, &flags)) {
+                rcu_read_unlock();
+                return;
+        }
 
         switch (who) {
                 case RUSAGE_BOTH:
                 case RUSAGE_CHILDREN:
-                        spin_lock_irqsave(&p->sighand->siglock, flags);
                         utime = p->signal->cutime;
                         stime = p->signal->cstime;
                         r->ru_nvcsw = p->signal->cnvcsw;
                         r->ru_nivcsw = p->signal->cnivcsw;
                         r->ru_minflt = p->signal->cmin_flt;
                         r->ru_majflt = p->signal->cmaj_flt;
-                        spin_unlock_irqrestore(&p->sighand->siglock, flags);
 
                         if (who == RUSAGE_CHILDREN)
                                 break;
@@ -1941,8 +1932,9 @@ static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
                         BUG();
         }
 
-        if (need_lock)
-                read_unlock(&tasklist_lock);
+        unlock_task_sighand(p, &flags);
+        rcu_read_unlock();
+
         cputime_to_timeval(utime, &r->ru_utime);
         cputime_to_timeval(stime, &r->ru_stime);
 }
@@ -1991,7 +1983,7 @@ asmlinkage long sys_prctl(int option, unsigned long arg2, unsigned long arg3,
                         error = current->mm->dumpable;
                         break;
                 case PR_SET_DUMPABLE:
-                        if (arg2 < 0 || arg2 > 2) {
+                        if (arg2 < 0 || arg2 > 1) {
                                 error = -EINVAL;
                                 break;
                         }
@@ -2057,6 +2049,13 @@ asmlinkage long sys_prctl(int option, unsigned long arg2, unsigned long arg3,
                                 return -EFAULT;
                         return 0;
                 }
+                case PR_GET_ENDIAN:
+                        error = GET_ENDIAN(current, arg2);
+                        break;
+                case PR_SET_ENDIAN:
+                        error = SET_ENDIAN(current, arg2);
+                        break;
+
                 default:
                         error = -EINVAL;
                         break;