[patch 1/3] Drop tasklist lock in do_sched_setscheduler

[Thomas Gleixner]

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@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>

 kernel/sched.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Index: linux-2.6.17-mm/kernel/sched.c
===================================================================
--- linux-2.6.17-mm.orig/kernel/sched.c	2006-06-22 10:26:11.000000000 +0200
+++ linux-2.6.17-mm/kernel/sched.c	2006-06-22 10:26:11.000000000 +0200
@@ -4140,8 +4140,10 @@
 		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;
 }
 

--

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