From: Alexandre Belloni <alexandre.belloni@bootlin•com>
To: Vladimir Oltean <vladimir.oltean@nxp•com>
Cc: Tobias Waldekranz <tobias@waldekranz•com>,
"David S . Miller" <davem@davemloft•net>,
Jakub Kicinski <kuba@kernel•org>,
netdev@vger•kernel.org, UNGLinuxDriver@microchip•com,
Andrew Lunn <andrew@lunn•ch>,
Florian Fainelli <f.fainelli@gmail•com>,
Vivien Didelot <vivien.didelot@gmail•com>,
Claudiu Manoil <claudiu.manoil@nxp•com>
Subject: Re: [RFC PATCH net-next 08/16] net: mscc: ocelot: avoid unneeded "lp" variable in LAG join
Date: Tue, 15 Dec 2020 17:47:56 +0100 [thread overview]
Message-ID: <20201215164756.GL1781038@piout.net> (raw)
In-Reply-To: <20201208120802.1268708-9-vladimir.oltean@nxp.com>
On 08/12/2020 14:07:54+0200, Vladimir Oltean wrote:
> 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@nxp•com>
Reviewed-by: Alexandre Belloni <alexandre.belloni@bootlin•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
>
--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
next prev parent reply other threads:[~2020-12-15 16:49 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-08 12:07 [RFC PATCH net-next 00/16] LAG offload for Ocelot DSA switches Vladimir Oltean
2020-12-08 12:07 ` [RFC PATCH net-next 01/16] net: mscc: ocelot: offload bridge port flags to device Vladimir Oltean
2020-12-15 14:37 ` Alexandre Belloni
2020-12-08 12:07 ` [RFC PATCH net-next 02/16] net: mscc: ocelot: allow offloading of bridge on top of LAG Vladimir Oltean
2020-12-15 14:43 ` Alexandre Belloni
2020-12-08 12:07 ` [RFC PATCH net-next 03/16] net: mscc: ocelot: rename ocelot_netdevice_port_event to ocelot_netdevice_changeupper Vladimir Oltean
2020-12-15 15:01 ` Alexandre Belloni
2020-12-15 15:27 ` Vladimir Oltean
2020-12-08 12:07 ` [RFC PATCH net-next 04/16] net: mscc: ocelot: use a switch-case statement in ocelot_netdevice_event Vladimir Oltean
2020-12-15 15:52 ` Alexandre Belloni
2020-12-15 15:56 ` Alexandre Belloni
2020-12-08 12:07 ` [RFC PATCH net-next 05/16] net: mscc: ocelot: don't refuse bonding interfaces we can't offload Vladimir Oltean
2020-12-15 15:56 ` Alexandre Belloni
2020-12-08 12:07 ` [RFC PATCH net-next 06/16] net: mscc: ocelot: use ipv6 in the aggregation code Vladimir Oltean
2020-12-15 16:03 ` Alexandre Belloni
2020-12-08 12:07 ` [RFC PATCH net-next 07/16] net: mscc: ocelot: set up the bonding mask in a way that avoids a net_device Vladimir Oltean
2020-12-15 16:36 ` Alexandre Belloni
2020-12-08 12:07 ` [RFC PATCH net-next 08/16] net: mscc: ocelot: avoid unneeded "lp" variable in LAG join Vladimir Oltean
2020-12-15 16:47 ` Alexandre Belloni [this message]
2020-12-08 12:07 ` [RFC PATCH net-next 09/16] net: mscc: ocelot: use "lag" variable name in ocelot_bridge_stp_state_set Vladimir Oltean
2020-12-15 16:49 ` Alexandre Belloni
2020-12-08 12:07 ` [RFC PATCH net-next 10/16] net: mscc: ocelot: reapply bridge forwarding mask on bonding join/leave Vladimir Oltean
2020-12-16 12:29 ` Alexandre Belloni
2020-12-08 12:07 ` [RFC PATCH net-next 11/16] net: mscc: ocelot: set up logical port IDs centrally Vladimir Oltean
2020-12-16 20:15 ` Alexandre Belloni
2020-12-08 12:07 ` [RFC PATCH net-next 12/16] net: mscc: ocelot: drop the use of the "lags" array Vladimir Oltean
2020-12-16 21:29 ` Alexandre Belloni
2021-01-15 11:05 ` Vladimir Oltean
2021-01-15 12:02 ` Alexandre Belloni
2020-12-08 12:07 ` [RFC PATCH net-next 13/16] net: mscc: ocelot: rename aggr_count to num_ports_in_lag Vladimir Oltean
2020-12-16 21:31 ` Alexandre Belloni
2020-12-08 12:08 ` [RFC PATCH net-next 14/16] net: mscc: ocelot: rebalance LAGs on link up/down events Vladimir Oltean
2020-12-16 21:32 ` Alexandre Belloni
2020-12-08 12:08 ` [RFC PATCH net-next 15/16] net: dsa: felix: propagate the LAG offload ops towards the ocelot lib Vladimir Oltean
2020-12-08 12:08 ` [RFC PATCH net-next 16/16] net: dsa: ocelot: tell DSA that we can offload link aggregation Vladimir Oltean
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