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From:   Dmitry Antipov <dmantipov@yandex.ru>
To:     Johannes Berg <johannes@sipsolutions.net>
Cc:     linux-wireless@vger.kernel.org,
        Dmitry Antipov <dmantipov@yandex.ru>
Subject: [PATCH] [v2] wifi: wext: avoid extra calls to strlen() in ieee80211_bss()
Date:   Tue, 12 Sep 2023 06:55:16 +0300
Message-ID: <20230912035522.15947-1-dmantipov@yandex.ru>
In-Reply-To: <3fe90164dc6fe7471523de1d3a234c88c0e43e46.camel@sipsolutions.net>
References: <3fe90164dc6fe7471523de1d3a234c88c0e43e46.camel@sipsolutions.net>
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Since 'sprintf()' returns the number of characters emitted, an
extra calls to 'strlen()' in 'ieee80211_bss()' may be dropped.

Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
---
v2: fix subject and reformat strings to avoid breaks (Johannes Berg)
---
 net/wireless/scan.c | 47 ++++++++++++++++++++++++---------------------
 1 file changed, 25 insertions(+), 22 deletions(-)

diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index 19516073c6d5..ae4d000009fe 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -3422,59 +3422,63 @@ ieee80211_bss(struct wiphy *wiphy, struct iw_request_info *info,
 			cfg = (u8 *)ie + 2;
 			memset(&iwe, 0, sizeof(iwe));
 			iwe.cmd = IWEVCUSTOM;
-			sprintf(buf, "Mesh Network Path Selection Protocol ID: "
-				"0x%02X", cfg[0]);
-			iwe.u.data.length = strlen(buf);
+			iwe.u.data.length = sprintf(buf,
+						    "Mesh Network Path Selection Protocol ID: 0x%02X",
+						    cfg[0]);
 			current_ev = iwe_stream_add_point_check(info,
 								current_ev,
 								end_buf,
 								&iwe, buf);
 			if (IS_ERR(current_ev))
 				goto unlock;
-			sprintf(buf, "Path Selection Metric ID: 0x%02X",
-				cfg[1]);
-			iwe.u.data.length = strlen(buf);
+			iwe.u.data.length = sprintf(buf,
+						    "Path Selection Metric ID: 0x%02X",
+						    cfg[1]);
 			current_ev = iwe_stream_add_point_check(info,
 								current_ev,
 								end_buf,
 								&iwe, buf);
 			if (IS_ERR(current_ev))
 				goto unlock;
-			sprintf(buf, "Congestion Control Mode ID: 0x%02X",
-				cfg[2]);
-			iwe.u.data.length = strlen(buf);
+			iwe.u.data.length = sprintf(buf,
+						    "Congestion Control Mode ID: 0x%02X",
+						    cfg[2]);
 			current_ev = iwe_stream_add_point_check(info,
 								current_ev,
 								end_buf,
 								&iwe, buf);
 			if (IS_ERR(current_ev))
 				goto unlock;
-			sprintf(buf, "Synchronization ID: 0x%02X", cfg[3]);
-			iwe.u.data.length = strlen(buf);
+			iwe.u.data.length = sprintf(buf,
+						    "Synchronization ID: 0x%02X",
+						    cfg[3]);
 			current_ev = iwe_stream_add_point_check(info,
 								current_ev,
 								end_buf,
 								&iwe, buf);
 			if (IS_ERR(current_ev))
 				goto unlock;
-			sprintf(buf, "Authentication ID: 0x%02X", cfg[4]);
-			iwe.u.data.length = strlen(buf);
+			iwe.u.data.length = sprintf(buf,
+						    "Authentication ID: 0x%02X",
+						    cfg[4]);
 			current_ev = iwe_stream_add_point_check(info,
 								current_ev,
 								end_buf,
 								&iwe, buf);
 			if (IS_ERR(current_ev))
 				goto unlock;
-			sprintf(buf, "Formation Info: 0x%02X", cfg[5]);
-			iwe.u.data.length = strlen(buf);
+			iwe.u.data.length = sprintf(buf,
+						    "Formation Info: 0x%02X",
+						    cfg[5]);
 			current_ev = iwe_stream_add_point_check(info,
 								current_ev,
 								end_buf,
 								&iwe, buf);
 			if (IS_ERR(current_ev))
 				goto unlock;
-			sprintf(buf, "Capabilities: 0x%02X", cfg[6]);
-			iwe.u.data.length = strlen(buf);
+			iwe.u.data.length = sprintf(buf,
+						    "Capabilities: 0x%02X",
+						    cfg[6]);
 			current_ev = iwe_stream_add_point_check(info,
 								current_ev,
 								end_buf,
@@ -3530,17 +3534,16 @@ ieee80211_bss(struct wiphy *wiphy, struct iw_request_info *info,
 
 	memset(&iwe, 0, sizeof(iwe));
 	iwe.cmd = IWEVCUSTOM;
-	sprintf(buf, "tsf=%016llx", (unsigned long long)(ies->tsf));
-	iwe.u.data.length = strlen(buf);
+	iwe.u.data.length = sprintf(buf, "tsf=%016llx",
+				    (unsigned long long)(ies->tsf));
 	current_ev = iwe_stream_add_point_check(info, current_ev, end_buf,
 						&iwe, buf);
 	if (IS_ERR(current_ev))
 		goto unlock;
 	memset(&iwe, 0, sizeof(iwe));
 	iwe.cmd = IWEVCUSTOM;
-	sprintf(buf, " Last beacon: %ums ago",
-		elapsed_jiffies_msecs(bss->ts));
-	iwe.u.data.length = strlen(buf);
+	iwe.u.data.length = sprintf(buf, " Last beacon: %ums ago",
+				    elapsed_jiffies_msecs(bss->ts));
 	current_ev = iwe_stream_add_point_check(info, current_ev,
 						end_buf, &iwe, buf);
 	if (IS_ERR(current_ev))
-- 
2.41.0