Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
blk-mq-debugfs: warn about possible deadlock
Creating new debugfs entries can trigger fs reclaim, hence we can't do
this with queue frozen, meanwhile, other locks that can be held while
queue is frozen should not be held as well.
Signed-off-by: Yu Kuai <yukuai@fnnas.com>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
authored by
Yu Kuai
and committed by
Jens Axboe
65d466b6
9d20fd6c
+24
-7
+24
-7
block/blk-mq-debugfs.c
+24
-7
block/blk-mq-debugfs.c
···
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{},
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};
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-
static void debugfs_create_files(struct dentry *parent, void *data,
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static void debugfs_create_files(struct request_queue *q, struct dentry *parent,
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void *data,
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const struct blk_mq_debugfs_attr *attr)
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{
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lockdep_assert_held(&q->debugfs_mutex);
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/*
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* Creating new debugfs entries with queue freezed has the risk of
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* deadlock.
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*/
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WARN_ON_ONCE(q->mq_freeze_depth != 0);
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/*
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* debugfs_mutex should not be nested under other locks that can be
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* grabbed while queue is frozen.
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*/
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lockdep_assert_not_held(&q->elevator_lock);
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lockdep_assert_not_held(&q->rq_qos_mutex);
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if (IS_ERR_OR_NULL(parent))
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return;
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···
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struct blk_mq_hw_ctx *hctx;
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unsigned long i;
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debugfs_create_files(q->debugfs_dir, q, blk_mq_debugfs_queue_attrs);
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debugfs_create_files(q, q->debugfs_dir, q, blk_mq_debugfs_queue_attrs);
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queue_for_each_hw_ctx(q, hctx, i) {
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if (!hctx->debugfs_dir)
···
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snprintf(name, sizeof(name), "cpu%u", ctx->cpu);
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ctx_dir = debugfs_create_dir(name, hctx->debugfs_dir);
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debugfs_create_files(ctx_dir, ctx, blk_mq_debugfs_ctx_attrs);
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debugfs_create_files(hctx->queue, ctx_dir, ctx,
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blk_mq_debugfs_ctx_attrs);
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}
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void blk_mq_debugfs_register_hctx(struct request_queue *q,
···
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snprintf(name, sizeof(name), "hctx%u", hctx->queue_num);
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hctx->debugfs_dir = debugfs_create_dir(name, q->debugfs_dir);
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debugfs_create_files(hctx->debugfs_dir, hctx, blk_mq_debugfs_hctx_attrs);
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debugfs_create_files(q, hctx->debugfs_dir, hctx,
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blk_mq_debugfs_hctx_attrs);
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hctx_for_each_ctx(hctx, ctx, i)
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blk_mq_debugfs_register_ctx(hctx, ctx);
···
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q->sched_debugfs_dir = debugfs_create_dir("sched", q->debugfs_dir);
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debugfs_create_files(q->sched_debugfs_dir, q, e->queue_debugfs_attrs);
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debugfs_create_files(q, q->sched_debugfs_dir, q, e->queue_debugfs_attrs);
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}
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void blk_mq_debugfs_unregister_sched(struct request_queue *q)
···
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q->debugfs_dir);
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rqos->debugfs_dir = debugfs_create_dir(dir_name, q->rqos_debugfs_dir);
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debugfs_create_files(rqos->debugfs_dir, rqos, rqos->ops->debugfs_attrs);
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debugfs_create_files(q, rqos->debugfs_dir, rqos,
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rqos->ops->debugfs_attrs);
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}
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void blk_mq_debugfs_register_rq_qos(struct request_queue *q)
···
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hctx->sched_debugfs_dir = debugfs_create_dir("sched",
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hctx->debugfs_dir);
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debugfs_create_files(hctx->sched_debugfs_dir, hctx,
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debugfs_create_files(q, hctx->sched_debugfs_dir, hctx,
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e->hctx_debugfs_attrs);
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}
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