[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>

diff --git a/kernel/sched.c b/kernel/sched.c
index 08431f07a999f56e7be0f2f685f19df7119264ac..7a30addfd235f73195fca9943c7e9d80bba617f2 100644 (file)
--- 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;
 }