Messages in this thread | | | Date | Mon, 14 May 2018 05:42:30 -0700 | From | Christoph Hellwig <> | Subject | Re: [PATCH] nvme: fix lockdep warning in nvme_mpath_clear_current_path |
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> extern unsigned int nvme_io_timeout; > #define NVME_IO_TIMEOUT (nvme_io_timeout * HZ) > @@ -454,7 +455,9 @@ static inline void nvme_mpath_clear_current_path(struct nvme_ns *ns) > { > struct nvme_ns_head *head = ns->head; > > - if (head && ns == srcu_dereference(head->current_path, &head->srcu)) > + if (head && > + ns == rcu_dereference_protected(head->current_path, > + lockdep_is_held(&ns->ctrl->subsys->lock))) > rcu_assign_pointer(head->current_path, NULL); > } > struct nvme_ns *nvme_find_path(struct nvme_ns_head *head);
We don't really dereference it at all in fact, but just check the pointers for equality. I wonder if there is a better way to do this, as my ANA patches add a caller without the lock (and withou SRU protection either now that I think of it) - for a pure pointer compare we really should not need any sort of protection.
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