Messages in this thread | | | Subject | Re: [PATCH] blk-mq-fs: invoke queue_for_each_hw_ctx under sysfs_lock | From | Bart Van Assche <> | Date | Tue, 26 Jun 2018 08:29:33 -0700 |
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On 06/24/18 23:20, Jianchao Wang wrote: > blk_mq_run_hw_queues and blk_mq_start_stopped_hw_queues in > queue_state_write will invoke queue_for_each_hw_ctx. It will race > with blk_mq_realloc_hw_ctxs and incur NULL pointer reference. Put > them under sysfs_lock to serialize the accessing to queue_hw_ctx > and nr_hw_queues.
The above looks wrong to me. blk_mq_realloc_hw_ctxs() starts with calling blk_mq_unregister_hctx(). That last function uses kobject_del() and kobject_del() waits until all pending sysfs callback functions for the deleted objects have finished.
Bart.
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