Linux Ethernet Bridging - Nov 2021 - [Bridge] [PATCH] net: bridge: Slightly optimize 'find_portno()'

The 'inuse' bitmap is local to this function. So we can use the
non-atomic '__set_bit()' to save a few cycles.

While at it, also remove some useless {}.

Signed-off-by: Christophe JAILLET <christophe.jaillet at wanadoo.fr>
---
 net/bridge/br_if.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index c1183fef1f21..64b2d4fb50f5 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -397,10 +397,10 @@ static int find_portno(struct net_bridge *br)
 	if (!inuse)
 		return -ENOMEM;
 
-	set_bit(0, inuse);	/* zero is reserved */
-	list_for_each_entry(p, &br->port_list, list) {
-		set_bit(p->port_no, inuse);
-	}
+	__set_bit(0, inuse);	/* zero is reserved */
+	list_for_each_entry(p, &br->port_list, list)
+		__set_bit(p->port_no, inuse);
+
 	index = find_first_zero_bit(inuse, BR_MAX_PORTS);
 	bitmap_free(inuse);
 
-- 
2.30.2

On Sun, Nov 14, 2021 at 08:02:35PM +0100, Christophe JAILLET
wrote:
> The 'inuse' bitmap is local to this function. So we can use the
> non-atomic '__set_bit()' to save a few cycles.
> 
> While at it, also remove some useless {}.
I like the {} and tend to add it in new code.  There isn't a rule about
this one way or the other.

regards,
dan carpenter

On 14/11/2021 21:02, Christophe JAILLET wrote:
> The 'inuse' bitmap is local to this function. So we can use the
> non-atomic '__set_bit()' to save a few cycles.
> 
> While at it, also remove some useless {}.
> 
> Signed-off-by: Christophe JAILLET <christophe.jaillet at wanadoo.fr>
> ---
>  net/bridge/br_if.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
> index c1183fef1f21..64b2d4fb50f5 100644
> --- a/net/bridge/br_if.c
> +++ b/net/bridge/br_if.c
> @@ -397,10 +397,10 @@ static int find_portno(struct net_bridge *br)
>  	if (!inuse)
>  		return -ENOMEM;
>  
> -	set_bit(0, inuse);	/* zero is reserved */
> -	list_for_each_entry(p, &br->port_list, list) {
> -		set_bit(p->port_no, inuse);
> -	}
> +	__set_bit(0, inuse);	/* zero is reserved */
> +	list_for_each_entry(p, &br->port_list, list)
> +		__set_bit(p->port_no, inuse);
> +
>  	index = find_first_zero_bit(inuse, BR_MAX_PORTS);
>  	bitmap_free(inuse);
>  
> 
This should be targeted at net-next.
The patch itself looks ok, TBH it's a slow path so speed
doesn't really matter but it's a straight-forward change.

Acked-by: Nikolay Aleksandrov <nikolay at nvidia.com>

Hello:

This patch was applied to netdev/net-next.git (master)
by David S. Miller <davem at davemloft.net>:

On Sun, 14 Nov 2021 20:02:35 +0100 you wrote:
> The 'inuse' bitmap is local to this function. So we can use the
> non-atomic '__set_bit()' to save a few cycles.
> 
> While at it, also remove some useless {}.
> 
> Signed-off-by: Christophe JAILLET <christophe.jaillet at wanadoo.fr>
> 
> [...]
Here is the summary with links:
  - net: bridge: Slightly optimize 'find_portno()'
    https://git.kernel.org/netdev/net-next/c/cc0be1ad686f

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html