linux-kernel - [PATCH v2 10/15] nvmet-fc: take tgtport reference only once

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Message-Id: <20250311-nvmet-fcloop-v2-10-fc40cb64edea@kernel.org>
Date: Tue, 11 Mar 2025 11:11:36 +0100
From: Daniel Wagner <wagi@...nel.org>
To: James Smart <james.smart@...adcom.com>, Christoph Hellwig <hch@....de>, 
 Sagi Grimberg <sagi@...mberg.me>, Chaitanya Kulkarni <kch@...dia.com>
Cc: Hannes Reinecke <hare@...e.de>, Keith Busch <kbusch@...nel.org>, 
 linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 Daniel Wagner <wagi@...nel.org>
Subject: [PATCH v2 10/15] nvmet-fc: take tgtport reference only once

The reference counting code can be simplified. Instead taking a tgtport
refrerence at the beginning of nvmet_fc_alloc_hostport and put it back
if not a new hostport object is allocated, only take it when a new
hostport object is allocated.

Signed-off-by: Daniel Wagner <wagi@...nel.org>
---
 drivers/nvme/target/fc.c | 24 +++++++++---------------
 1 file changed, 9 insertions(+), 15 deletions(-)

diff --git a/drivers/nvme/target/fc.c b/drivers/nvme/target/fc.c
index b807b4c05cac7fe4764df3df76f8fa50f4bab6ba..810aff9901da725086f8bd76f3320fb31696468f 100644
--- a/drivers/nvme/target/fc.c
+++ b/drivers/nvme/target/fc.c
@@ -1042,33 +1042,26 @@ nvmet_fc_alloc_hostport(struct nvmet_fc_tgtport *tgtport, void *hosthandle)
 	struct nvmet_fc_hostport *newhost, *match = NULL;
 	unsigned long flags;
 
+	/*
+	 * A ref on tgtport is being held while executing this function,
+	 * thus there is no need to take first one and give it back on
+	 * exit.
+	 */
+
 	/* if LLDD not implemented, leave as NULL */
 	if (!hosthandle)
 		return NULL;
 
-	/*
-	 * take reference for what will be the newly allocated hostport if
-	 * we end up using a new allocation
-	 */
-	if (!nvmet_fc_tgtport_get(tgtport))
-		return ERR_PTR(-EINVAL);
-
 	spin_lock_irqsave(&tgtport->lock, flags);
 	match = nvmet_fc_match_hostport(tgtport, hosthandle);
 	spin_unlock_irqrestore(&tgtport->lock, flags);
 
-	if (match) {
-		/* no new allocation - release reference */
-		nvmet_fc_tgtport_put(tgtport);
+	if (match)
 		return match;
-	}
 
 	newhost = kzalloc(sizeof(*newhost), GFP_KERNEL);
-	if (!newhost) {
-		/* no new allocation - release reference */
-		nvmet_fc_tgtport_put(tgtport);
+	if (!newhost)
 		return ERR_PTR(-ENOMEM);
-	}
 
 	spin_lock_irqsave(&tgtport->lock, flags);
 	match = nvmet_fc_match_hostport(tgtport, hosthandle);
@@ -1077,6 +1070,7 @@ nvmet_fc_alloc_hostport(struct nvmet_fc_tgtport *tgtport, void *hosthandle)
 		kfree(newhost);
 		newhost = match;
 	} else {
+		nvmet_fc_tgtport_get(tgtport);
 		newhost->tgtport = tgtport;
 		newhost->hosthandle = hosthandle;
 		INIT_LIST_HEAD(&newhost->host_list);

-- 
2.48.1