Commit 6d1c6994 authored by Breno Leitao's avatar Breno Leitao Committed by Keith Busch
Browse files

nvme/host: Fix RCU list traversal to use SRCU primitive 



The code currently uses list_for_each_entry_rcu() while holding an SRCU
lock, triggering false positive warnings with CONFIG_PROVE_RCU=y
enabled:

  drivers/nvme/host/core.c:3770 RCU-list traversed in non-reader section!!

While the list is properly protected by SRCU lock, the code uses the wrong
list traversal primitive. Replace list_for_each_entry_rcu() with
list_for_each_entry_srcu() to correctly indicate SRCU-based protection
and eliminate the false warning.

Fixes: be647e2c ("nvme: use srcu for iterating namespace list")
Signed-off-by: default avatarBreno Leitao <leitao@debian.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarKeith Busch <kbusch@kernel.org>
parent d0c6cc6c

drivers/nvme/host/core.c

+14 −7
Original line number Diff line number Diff line
@@ -3795,7 +3795,8 @@ struct nvme_ns *nvme_find_get_ns(struct nvme_ctrl *ctrl, unsigned nsid) 
	int srcu_idx;



	srcu_idx = srcu_read_lock(&ctrl->srcu);

	list_for_each_entry_rcu(ns, &ctrl->namespaces, list) {

	list_for_each_entry_srcu(ns, &ctrl->namespaces, list,

				 srcu_read_lock_held(&ctrl->srcu)) {

		if (ns->head->ns_id == nsid) {

			if (!nvme_get_ns(ns))

				continue;
@@ -4879,7 +4880,8 @@ void nvme_mark_namespaces_dead(struct nvme_ctrl *ctrl) 
	int srcu_idx;



	srcu_idx = srcu_read_lock(&ctrl->srcu);

	list_for_each_entry_rcu(ns, &ctrl->namespaces, list)

	list_for_each_entry_srcu(ns, &ctrl->namespaces, list,

				 srcu_read_lock_held(&ctrl->srcu))

		blk_mark_disk_dead(ns->disk);

	srcu_read_unlock(&ctrl->srcu, srcu_idx);

}
@@ -4891,7 +4893,8 @@ void nvme_unfreeze(struct nvme_ctrl *ctrl) 
	int srcu_idx;



	srcu_idx = srcu_read_lock(&ctrl->srcu);

	list_for_each_entry_rcu(ns, &ctrl->namespaces, list)

	list_for_each_entry_srcu(ns, &ctrl->namespaces, list,

				 srcu_read_lock_held(&ctrl->srcu))

		blk_mq_unfreeze_queue(ns->queue);

	srcu_read_unlock(&ctrl->srcu, srcu_idx);

	clear_bit(NVME_CTRL_FROZEN, &ctrl->flags);
@@ -4904,7 +4907,8 @@ int nvme_wait_freeze_timeout(struct nvme_ctrl *ctrl, long timeout) 
	int srcu_idx;



	srcu_idx = srcu_read_lock(&ctrl->srcu);

	list_for_each_entry_rcu(ns, &ctrl->namespaces, list) {

	list_for_each_entry_srcu(ns, &ctrl->namespaces, list,

				 srcu_read_lock_held(&ctrl->srcu)) {

		timeout = blk_mq_freeze_queue_wait_timeout(ns->queue, timeout);

		if (timeout <= 0)

			break;
@@ -4920,7 +4924,8 @@ void nvme_wait_freeze(struct nvme_ctrl *ctrl) 
	int srcu_idx;



	srcu_idx = srcu_read_lock(&ctrl->srcu);

	list_for_each_entry_rcu(ns, &ctrl->namespaces, list)

	list_for_each_entry_srcu(ns, &ctrl->namespaces, list,

				 srcu_read_lock_held(&ctrl->srcu))

		blk_mq_freeze_queue_wait(ns->queue);

	srcu_read_unlock(&ctrl->srcu, srcu_idx);

}
@@ -4933,7 +4938,8 @@ void nvme_start_freeze(struct nvme_ctrl *ctrl) 


	set_bit(NVME_CTRL_FROZEN, &ctrl->flags);

	srcu_idx = srcu_read_lock(&ctrl->srcu);

	list_for_each_entry_rcu(ns, &ctrl->namespaces, list)

	list_for_each_entry_srcu(ns, &ctrl->namespaces, list,

				 srcu_read_lock_held(&ctrl->srcu))

		blk_freeze_queue_start(ns->queue);

	srcu_read_unlock(&ctrl->srcu, srcu_idx);

}
@@ -4981,7 +4987,8 @@ void nvme_sync_io_queues(struct nvme_ctrl *ctrl) 
	int srcu_idx;



	srcu_idx = srcu_read_lock(&ctrl->srcu);

	list_for_each_entry_rcu(ns, &ctrl->namespaces, list)

	list_for_each_entry_srcu(ns, &ctrl->namespaces, list,

				 srcu_read_lock_held(&ctrl->srcu))

		blk_sync_queue(ns->queue);

	srcu_read_unlock(&ctrl->srcu, srcu_idx);

}