[PATCH] Drop tasklist lock in do_sched_setscheduler

There is no need to hold tasklist_lock across the setscheduler call, when
we pin the task structure with get_task_struct().  Interrupts are disabled
in setscheduler anyway and the permission checks do not need interrupts
disabled.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 08431f07a999..7a30addfd235 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4091,8 +4091,10 @@ do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
                 read_unlock_irq(&tasklist_lock);
                 return -ESRCH;
         }
-        retval = sched_setscheduler(p, policy, &lparam);
+        get_task_struct(p);
         read_unlock_irq(&tasklist_lock);
+        retval = sched_setscheduler(p, policy, &lparam);
+        put_task_struct(p);
         return retval;
 }