[PATCH 6.6 25/48] nvme/host: Fix RCU list traversal to use SRCU primitive

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

6.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Breno Leitao <leitao@debian.org>

[ 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>
---
 drivers/nvme/host/core.c | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index b3c5460c6d768..965ca7d7a3de2 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -3544,7 +3544,8 @@ 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;
@@ -4555,7 +4556,8 @@ 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);
 }
@@ -4567,7 +4569,8 @@ 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);
@@ -4580,7 +4583,8 @@ 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;
@@ -4596,7 +4600,8 @@ 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);
 }
@@ -4609,7 +4614,8 @@ 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);
 }
@@ -4657,7 +4663,8 @@ 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);
 }
-- 
2.43.0