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lockdep: change scheduler annotation 

While thinking about David's graph walk lockdep patch it _finally_
dawned on me that there is no reason we have a lock class per cpu ...

Sorry for being dense :-/

The below changes the annotation from a lock class per cpu, to a single
nested lock, as the scheduler never holds more that 2 rq locks at a time
anyway.

If there was code requiring holding all rq locks this would not work and
the original annotation would be the only option, but that not being the
case, this is a much lighter one.

Compiles and boots on a 2-way x86_64.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2008-07-30 13:26:57 +02:00 committed by Ingo Molnar
parent e0fdace10e
commit 5e710e37bd
1 changed files with 4 additions and 6 deletions
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10
kernel/sched.c
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@ -600,7 +600,6 @@ struct rq {
/* BKL stats */
unsigned int bkl_count;
#endif
struct lock_class_key rq_lock_key;
};
static DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
@ -2759,10 +2758,10 @@ static void double_rq_lock(struct rq *rq1, struct rq *rq2)
} else {
if (rq1 < rq2) {
spin_lock(&rq1->lock);
spin_lock(&rq2->lock);
spin_lock_nested(&rq2->lock, SINGLE_DEPTH_NESTING);
} else {
spin_lock(&rq2->lock);
spin_lock(&rq1->lock);
spin_lock_nested(&rq1->lock, SINGLE_DEPTH_NESTING);
}
}
update_rq_clock(rq1);
@ -2805,10 +2804,10 @@ static int double_lock_balance(struct rq *this_rq, struct rq *busiest)
if (busiest < this_rq) {
spin_unlock(&this_rq->lock);
spin_lock(&busiest->lock);
spin_lock(&this_rq->lock);
spin_lock_nested(&this_rq->lock, SINGLE_DEPTH_NESTING);
ret = 1;
} else
spin_lock(&busiest->lock);
spin_lock_nested(&busiest->lock, SINGLE_DEPTH_NESTING);
}
return ret;
}
@ -7998,7 +7997,6 @@ void __init sched_init(void)
rq = cpu_rq(i);
spin_lock_init(&rq->lock);
lockdep_set_class(&rq->lock, &rq->rq_lock_key);
rq->nr_running = 0;
init_cfs_rq(&rq->cfs, rq);
init_rt_rq(&rq->rt, rq);