netdev - [RFC PATCH net-next 08/16] net: mscc: ocelot: avoid unneeded "lp" variable in LAG join

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue,  8 Dec 2020 14:07:54 +0200
From:   Vladimir Oltean <vladimir.oltean@....com>
To:     Tobias Waldekranz <tobias@...dekranz.com>
Cc:     "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        UNGLinuxDriver@...rochip.com,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Claudiu Manoil <claudiu.manoil@....com>
Subject: [RFC PATCH net-next 08/16] net: mscc: ocelot: avoid unneeded "lp" variable in LAG join

The index of the LAG is equal to the logical port ID that all the
physical port members have, which is further equal to the index of the
first physical port that is a member of the LAG.

The code gets a bit carried away with logic like this:

	if (a == b)
		c = a;
	else
		c = b;

which can be simplified, of course, into:

	c = b;

(with a being port, b being lp, c being lag)

This further makes the "lp" variable redundant, since we can use "lag"
everywhere where "lp" (logical port) was used. So instead of a "c = b"
assignment, we can do a complete deletion of b. Only one comment here:

		if (bond_mask) {
			lp = __ffs(bond_mask);
			ocelot->lags[lp] = 0;
		}

lp was clobbered before, because it was used as a temporary variable to
hold the new smallest port ID from the bond. Now that we don't have "lp"
any longer, we'll just avoid the temporary variable and zeroize the
bonding mask directly.

Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
---
 drivers/net/ethernet/mscc/ocelot.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/mscc/ocelot.c b/drivers/net/ethernet/mscc/ocelot.c
index 30dee1f957d1..080fd4ce37ea 100644
--- a/drivers/net/ethernet/mscc/ocelot.c
+++ b/drivers/net/ethernet/mscc/ocelot.c
@@ -1291,28 +1291,24 @@ int ocelot_port_lag_join(struct ocelot *ocelot, int port,
 			 struct net_device *bond)
 {
 	u32 bond_mask = 0;
-	int lag, lp;
+	int lag;
 
 	ocelot->ports[port]->bond = bond;
 
 	bond_mask = ocelot_get_bond_mask(ocelot, bond);
 
-	lp = __ffs(bond_mask);
+	lag = __ffs(bond_mask);
 
 	/* If the new port is the lowest one, use it as the logical port from
 	 * now on
 	 */
-	if (port == lp) {
-		lag = port;
+	if (port == lag) {
 		ocelot->lags[port] = bond_mask;
 		bond_mask &= ~BIT(port);
-		if (bond_mask) {
-			lp = __ffs(bond_mask);
-			ocelot->lags[lp] = 0;
-		}
+		if (bond_mask)
+			ocelot->lags[__ffs(bond_mask)] = 0;
 	} else {
-		lag = lp;
-		ocelot->lags[lp] |= BIT(port);
+		ocelot->lags[lag] |= BIT(port);
 	}
 
 	ocelot_setup_lag(ocelot, lag);
-- 
2.25.1