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

[ Upstream commit 6d1c69945ce63a9fba22a4abf646cf960d878782 ]

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: be647e2c76b2 ("nvme: use srcu for iterating namespace list")
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

1 files changed, 14 insertions, 7 deletions

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 89ad4217f860..b954e77d3fc5 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -3793,7 +3793,8 @@ 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;
@@ -4840,7 +4841,8 @@ 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);
 }
@@ -4852,7 +4854,8 @@ 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);
@@ -4865,7 +4868,8 @@ 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;
@@ -4881,7 +4885,8 @@ 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);
 }
@@ -4894,7 +4899,8 @@ 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);
 }
@@ -4942,7 +4948,8 @@ 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);
 }