linux-kernel - [PATCH v2 1/5] nvme-fc: don't hold rport lock when putting ctrl

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Message-Id: <20251030-nvmet-fcloop-fixes-v2-1-b8d66a322c51@kernel.org>
Date: Thu, 30 Oct 2025 11:05:45 +0100
From: Daniel Wagner <wagi@...nel.org>
To: Justin Tee <justin.tee@...adcom.com>, Christoph Hellwig <hch@....de>, 
 Keith Busch <kbusch@...nel.org>
Cc: James Smart <james.smart@...adcom.com>, Jens Axboe <axboe@...nel.dk>, 
 linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 Daniel Wagner <wagi@...nel.org>
Subject: [PATCH v2 1/5] nvme-fc: don't hold rport lock when putting ctrl

nvme_fc_ctrl_put can acquire the rport lock when freeing the
ctrl object:

nvme_fc_ctrl_put
  nvme_fc_ctrl_free
    spin_lock_irqsave(rport->lock)

Thus we can't hold the rport lock when calling nvme_fc_ctrl_put.

Justin suggested use the safe list iterator variant because
nvme_fc_ctrl_put will also modify the rport->list.

Cc: Justin Tee <justin.tee@...adcom.com>
Reviewed-by: Christoph Hellwig <hch@....de>
Signed-off-by: Daniel Wagner <wagi@...nel.org>
---
 drivers/nvme/host/fc.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
index 03987f497a5b..3ff70e6e8131 100644
--- a/drivers/nvme/host/fc.c
+++ b/drivers/nvme/host/fc.c
@@ -1468,14 +1468,14 @@ nvme_fc_match_disconn_ls(struct nvme_fc_rport *rport,
 {
 	struct fcnvme_ls_disconnect_assoc_rqst *rqst =
 					&lsop->rqstbuf->rq_dis_assoc;
-	struct nvme_fc_ctrl *ctrl, *ret = NULL;
+	struct nvme_fc_ctrl *ctrl, *tmp, *ret = NULL;
 	struct nvmefc_ls_rcv_op *oldls = NULL;
 	u64 association_id = be64_to_cpu(rqst->associd.association_id);
 	unsigned long flags;
 
 	spin_lock_irqsave(&rport->lock, flags);
 
-	list_for_each_entry(ctrl, &rport->ctrl_list, ctrl_list) {
+	list_for_each_entry_safe(ctrl, tmp, &rport->ctrl_list, ctrl_list) {
 		if (!nvme_fc_ctrl_get(ctrl))
 			continue;
 		spin_lock(&ctrl->lock);
@@ -1488,7 +1488,9 @@ nvme_fc_match_disconn_ls(struct nvme_fc_rport *rport,
 		if (ret)
 			/* leave the ctrl get reference */
 			break;
+		spin_unlock_irqrestore(&rport->lock, flags);
 		nvme_fc_ctrl_put(ctrl);
+		spin_lock_irqsave(&rport->lock, flags);
 	}
 
 	spin_unlock_irqrestore(&rport->lock, flags);

-- 
2.51.1