linux-kernel - Re: [PATCH] mmc: Use switch() instead of if/else if in mmc_blk_issue

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Message-ID: <m239gwglr9.fsf@bob.laptop.org>
Date:	Sat, 20 Aug 2011 11:12:26 -0400
From:	Chris Ball <cjb@...top.org>
To:	Namjae Jeon <linkinjeon@...il.com>
Cc:	linux-mmc@...r.kernel.org, linus.walleij@...aro.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mmc: Use switch() instead of if/else if in mmc_blk_issue_rq.

Hi,

On Sat, Aug 20 2011, Namjae Jeon wrote:
> This uses a switch statement instead of if/else if statements.
> It will make to improve clarity and scalability, and offer faster execution through compiler optimization than if/else if statements.
>
> Signed-off-by: Namjae Jeon <linkinjeon@...il.com>
> ---
>  drivers/mmc/card/block.c |   38 +++++++++++++++++++++++---------------
>  1 files changed, 23 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
> index 1ff5486..fe9dd89 100644
> --- a/drivers/mmc/card/block.c
> +++ b/drivers/mmc/card/block.c
> @@ -1191,23 +1191,31 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
>  		goto out;
>  	}
>  
> -	if (req && req->cmd_flags & REQ_DISCARD) {
> -		/* complete ongoing async transfer before issuing discard */
> -		if (card->host->areq)
> -			mmc_blk_issue_rw_rq(mq, NULL);
> -		if (req->cmd_flags & REQ_SECURE)
> -			ret = mmc_blk_issue_secdiscard_rq(mq, req);
> -		else
> +	if (req) {
> +		switch(req->cmd_flags) {
> +		case REQ_DISCARD:
> +			/* complete ongoing async transfer before issuing discard */
> +			if (card->host->areq)
> +				mmc_blk_issue_rw_rq(mq, NULL);

But it doesn't work, because you've changed the test for "req->cmd_flags
& REQ_DISCARD" into a test for "req->cmd_flags == REQ_DISCARD".

- Chris.
-- 
Chris Ball   <cjb@...top.org>   <http://printf.net/>
One Laptop Per Child
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