linux-kernel - [PATCH V1] firmware: arm_scmi: Optimize the iteration of scmi_requested

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Message-Id: <20250107052004.762817-1-peng.fan@oss.nxp.com>
Date: Tue,  7 Jan 2025 13:20:04 +0800
From: "Peng Fan (OSS)" <peng.fan@....nxp.com>
To: sudeep.holla@....com,
	cristian.marussi@....com,
	arm-scmi@...r.kernel.org
Cc: linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Peng Fan <peng.fan@....com>,
	Dan Carpenter <dan.carpenter@...aro.org>
Subject: [PATCH V1] firmware: arm_scmi: Optimize the iteration of scmi_requested_devices

From: Peng Fan <peng.fan@....com>

scmi_requested_devices is organized in IDR based link lists, so only
need to search the link lists when there is a match protocol_id.

Back to search the next id with 'continue' to save cpu cycles, if
protocol_id does not match.

Suggested-by: Dan Carpenter <dan.carpenter@...aro.org>
Signed-off-by: Peng Fan <peng.fan@....com>
---

V1:
 Follow Dan's suggestion

 drivers/firmware/arm_scmi/bus.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/drivers/firmware/arm_scmi/bus.c b/drivers/firmware/arm_scmi/bus.c
index 157172a5f2b5..c26f470fc24f 100644
--- a/drivers/firmware/arm_scmi/bus.c
+++ b/drivers/firmware/arm_scmi/bus.c
@@ -72,14 +72,11 @@ static int scmi_protocol_device_request(const struct scmi_device_id *id_table)
 	 */
 	mutex_lock(&scmi_requested_devices_mtx);
 	idr_for_each_entry(&scmi_requested_devices, head, id) {
-		if (!phead) {
-			/* A list found registered in the IDR is never empty */
-			rdev = list_first_entry(head, struct scmi_requested_dev,
-						node);
-			if (rdev->id_table->protocol_id ==
-			    id_table->protocol_id)
-				phead = head;
-		}
+		/* A list found registered in the IDR is never empty */
+		rdev = list_first_entry(head, struct scmi_requested_dev, node);
+		if (rdev->id_table->protocol_id != id_table->protocol_id)
+			continue;
+
 		list_for_each_entry(rdev, head, node) {
 			if (!strcmp(rdev->id_table->name, id_table->name)) {
 				pr_err("Ignoring duplicate request [%d] %s\n",
@@ -89,6 +86,8 @@ static int scmi_protocol_device_request(const struct scmi_device_id *id_table)
 				goto out;
 			}
 		}
+		phead = head;
+		break;
 	}
 
 	/*
-- 
2.37.1