Re: First kernel patch (optimization)

[Felipe Balbi]

On Tue, Sep 15, 2015 at 08:53:28PM +0100, Eric Curtin wrote:
> My first kernel patch, hope I did everything correctly! Instead of calling strlen on every iteration of the for loop, just call it once instead and store in a variable.

this should be broken up at 72 characters. Also, your subject and commit
log make no sense from a project history perspective. You don't need to
mention it's your first patch, just go straight to the details.

For the subject, I'd use something like:

tools: usbip: detach: avoid calling strlen() at each iteration

and for the commit log:

Instead of calling strlen() on every iterations of the for loop,
just call it once and cache the result in a temporary local variable
which will be used in the for loop instead.

cheers

> Signed-off-by: Eric Curtin <ericcurtin17@xxxxxxxxx>
> 
> diff --git a/tools/usb/usbip/src/usbip_detach.c b/tools/usb/usbip/src/usbip_detach.c
> index 05c6d15..9db9d21 100644
> --- a/tools/usb/usbip/src/usbip_detach.c
> +++ b/tools/usb/usbip/src/usbip_detach.c
> @@ -47,7 +47,9 @@ static int detach_port(char *port)
>  	uint8_t portnum;
>  	char path[PATH_MAX+1];
>  
> -	for (unsigned int i = 0; i < strlen(port); i++)
> +	unsigned int port_len = strlen(port);
> +
> +	for (unsigned int i = 0; i < port_len; i++)
>  		if (!isdigit(port[i])) {
>  			err("invalid port %s", port);
>  			return -1;
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/

-- 
balbi

Attachment: signature.asc
Description: Digital signature