blk-stat: don't use this_cpu_ptr() in a preemptable section (d3738123) · Commits · 戴 / test

If PREEMPT_RCU is enabled, rcu_read_lock() isn't strong enough for us to use this_cpu_ptr() in that section. Use the safer get/put_cpu_ptr() variants instead. Reported-by:

Mike Galbraith <efault@gmx.de> Fixes: ("blk-stat: convert to callback-based statistics reporting") Signed-off-by:

Jens Axboe <axboe@fb.com>

block/blk-stat.c

+10 −7

Original line number	Diff line number	Diff line
		@@ -96,13 +96,16 @@ void blk_stat_add(struct request *rq)

		rcu_read_lock();
		list_for_each_entry_rcu(cb, &q->stats->callbacks, list) {
		if (blk_stat_is_active(cb)) {
		if (!blk_stat_is_active(cb))
		continue;

		bucket = cb->bucket_fn(rq);
		if (bucket < 0)
		continue;
		stat = &this_cpu_ptr(cb->cpu_stat)[bucket];

		stat = &get_cpu_ptr(cb->cpu_stat)[bucket];
		__blk_stat_add(stat, value);
		}
		put_cpu_ptr(cb->cpu_stat);
		}
		rcu_read_unlock();
		}

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