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sched: remove migration notification from RT class

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Commit 88a7e37d265 (sched: provide per cpu-cgroup option to
notify on migrations) added a notifier call when a task is moved
to a different CPU. Unfortunately the two call sites in the RT
sched class where this occurs happens with a runqueue lock held.
This can result in a deadlock if the notifier call attempts to do
something like wake up a task.

Fortunately the benefit of 88a7e37d265 comes mainly from notifying
on migration of non-RT tasks, so we can simply ignore the movements
of RT tasks.

CRs-Fixed: 491370
Change-Id: I8849d826bf1eeaf85a6f6ad872acb475247c5926
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
Signed-off-by: Mekala Natarajan <mekalan@codeaurora.org>
This commit is contained in:
Mekala Natarajan 2013-05-30 00:01:09 -07:00 committed by Iliyan Malchev
parent 2dcb52455c
commit 14e8dbd63a
1 changed files with 1 additions and 19 deletions
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20
kernel/sched/rt.c
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@ -1604,7 +1604,6 @@ static int push_rt_task(struct rq *rq)
struct task_struct *next_task;
struct rq *lowest_rq;
int ret = 0;
bool moved = false;
if (!rq->rt.overloaded)
return 0;
@ -1674,7 +1673,6 @@ retry:
deactivate_task(rq, next_task, 0);
set_task_cpu(next_task, lowest_rq->cpu);
moved = true;
activate_task(lowest_rq, next_task, 0);
ret = 1;
@ -1685,11 +1683,6 @@ retry:
out:
put_task_struct(next_task);
if (moved && task_notify_on_migrate(next_task))
atomic_notifier_call_chain(&migration_notifier_head,
cpu_of(lowest_rq),
(void *)cpu_of(rq));
return ret;
}
@ -1703,10 +1696,8 @@ static void push_rt_tasks(struct rq *rq)
static int pull_rt_task(struct rq *this_rq)
{
int this_cpu = this_rq->cpu, ret = 0, cpu;
struct task_struct *p = NULL;
struct task_struct *p;
struct rq *src_rq;
bool moved = false;
int src_cpu = 0;
if (likely(!rt_overloaded(this_rq)))
return 0;
@ -1767,10 +1758,6 @@ static int pull_rt_task(struct rq *this_rq)
deactivate_task(src_rq, p, 0);
set_task_cpu(p, this_cpu);
activate_task(this_rq, p, 0);
moved = true;
src_cpu = cpu_of(src_rq);
/*
* We continue with the search, just in
* case there's an even higher prio task
@ -1782,11 +1769,6 @@ skip:
double_unlock_balance(this_rq, src_rq);
}
if (moved && task_notify_on_migrate(p))
atomic_notifier_call_chain(&migration_notifier_head,
this_cpu,
(void *)src_cpu);
return ret;
}