sched/core: Make dl_b->lock IRQ safe
Fix this lockdep warning:
[ 44.804600] =========================================================
[ 44.805746] [ INFO: possible irq lock inversion dependency detected ]
[ 44.805746] 3.14.0-rc2-test+ #14 Not tainted
[ 44.805746] ---------------------------------------------------------
[ 44.805746] bash/3674 just changed the state of lock:
[ 44.805746] (&dl_b->lock){+.....}, at: [<ffffffff8106ad15>] sched_rt_handler+0x132/0x248
[ 44.805746] but this lock was taken by another, HARDIRQ-safe lock in the past:
[ 44.805746] (&rq->lock){-.-.-.}
and interrupts could create inverse lock ordering between them.
[ 44.805746]
[ 44.805746] other info that might help us debug this:
[ 44.805746] Possible interrupt unsafe locking scenario:
[ 44.805746]
[ 44.805746] CPU0 CPU1
[ 44.805746] ---- ----
[ 44.805746] lock(&dl_b->lock);
[ 44.805746] local_irq_disable();
[ 44.805746] lock(&rq->lock);
[ 44.805746] lock(&dl_b->lock);
[ 44.805746] <Interrupt>
[ 44.805746] lock(&rq->lock);
by making dl_b->lock acquiring always IRQ safe.
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Juri Lelli <juri.lelli@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1392107067-19907-3-git-send-email-juri.lelli@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 98d33c10..33d030a 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7422,6 +7422,7 @@
u64 period = global_rt_period();
u64 new_bw = to_ratio(period, runtime);
int cpu, ret = 0;
+ unsigned long flags;
/*
* Here we want to check the bandwidth not being set to some
@@ -7435,10 +7436,10 @@
for_each_possible_cpu(cpu) {
struct dl_bw *dl_b = dl_bw_of(cpu);
- raw_spin_lock(&dl_b->lock);
+ raw_spin_lock_irqsave(&dl_b->lock, flags);
if (new_bw < dl_b->total_bw)
ret = -EBUSY;
- raw_spin_unlock(&dl_b->lock);
+ raw_spin_unlock_irqrestore(&dl_b->lock, flags);
if (ret)
break;
@@ -7451,6 +7452,7 @@
{
u64 new_bw = -1;
int cpu;
+ unsigned long flags;
def_dl_bandwidth.dl_period = global_rt_period();
def_dl_bandwidth.dl_runtime = global_rt_runtime();
@@ -7464,9 +7466,9 @@
for_each_possible_cpu(cpu) {
struct dl_bw *dl_b = dl_bw_of(cpu);
- raw_spin_lock(&dl_b->lock);
+ raw_spin_lock_irqsave(&dl_b->lock, flags);
dl_b->bw = new_bw;
- raw_spin_unlock(&dl_b->lock);
+ raw_spin_unlock_irqrestore(&dl_b->lock, flags);
}
}
