void blk_plug_device(struct request_queue *q)
{
WARN_ON(!irqs_disabled());
/*
* don't plug a stopped queue, it must be paired with blk_start_queue()
* which will restart the queueing
*/
if (blk_queue_stopped(q))
return;
if (!queue_flag_test_and_set(QUEUE_FLAG_PLUGGED, q)) {
mod_timer(&q->unplug_timer, jiffies + q->unplug_delay);
trace_block_plug(q);
}
}
EXPORT_SYMBOL(blk_plug_device);
commit 4cecf6d401a01d054afc1e5f605bcbfe553cb9b9
Author: Salman Qazi <sqazi@google.com>
Date: Tue Nov 15 14:12:06 2011 -0800
sched, x86: Avoid unnecessary overflow in sched_clock
(Added the missing signed-off-by line)
In hundreds of days, the __cycles_2_ns calculation in sched_clock
has an overflow. cyc * per_cpu(cyc2ns, cpu) exceeds 64 bits, causing
the final value to become zero. We can solve this without losing
any precision.
We can decompose TSC into quotient and remainder of division by the
scale factor, and then use this to convert TSC into nanoseconds.
Signed-off-by: Salman Qazi <sqazi@google.com>
Acked-by: John Stultz <johnstul@us.ibm.com>
Reviewed-by: Paul Turner <pjt@google.com>
Cc: stable@kernel.org
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20111115221121.7262.88871.stgit@dungbeetle.mtv.corp.google.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>