linux-kernel - [PATCH net-next] net: dsa: b53: Slightly optimize b53_arl

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Date:   Thu, 20 Apr 2023 22:44:10 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vladimir Oltean <olteanv@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Cc:     linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        netdev@...r.kernel.org
Subject: [PATCH net-next] net: dsa: b53: Slightly optimize b53_arl_read()

When the 'free_bins' bitmap is cleared, it is better to use its full
maximum size instead of only the needed size.
This lets the compiler optimize it because the size is now known at compile
time. B53_ARLTBL_MAX_BIN_ENTRIES is small (i.e. currently 4), so a call to
memset() is saved.

Also, as 'free_bins' is local to the function, the non-atomic __set_bit()
can also safely be used here.

Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
 drivers/net/dsa/b53/b53_common.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/dsa/b53/b53_common.c b/drivers/net/dsa/b53/b53_common.c
index 3464ce5e7470..8c55fe0e0747 100644
--- a/drivers/net/dsa/b53/b53_common.c
+++ b/drivers/net/dsa/b53/b53_common.c
@@ -1627,7 +1627,7 @@ static int b53_arl_read(struct b53_device *dev, u64 mac,
 	if (ret)
 		return ret;
 
-	bitmap_zero(free_bins, dev->num_arl_bins);
+	bitmap_zero(free_bins, B53_ARLTBL_MAX_BIN_ENTRIES);
 
 	/* Read the bins */
 	for (i = 0; i < dev->num_arl_bins; i++) {
@@ -1641,7 +1641,7 @@ static int b53_arl_read(struct b53_device *dev, u64 mac,
 		b53_arl_to_entry(ent, mac_vid, fwd_entry);
 
 		if (!(fwd_entry & ARLTBL_VALID)) {
-			set_bit(i, free_bins);
+			__set_bit(i, free_bins);
 			continue;
 		}
 		if ((mac_vid & ARLTBL_MAC_MASK) != mac)
-- 
2.34.1