[PATCH] mmc: Use switch() instead of if/else if in mmc_blk_issue_rq.

[PATCH] mmc: Use switch() instead of if/else if in mmc_blk_issue_rq.

[Namjae Jeon]

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@gmail.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);
 			ret = mmc_blk_issue_discard_rq(mq, req);
-	} else if (req && req->cmd_flags & REQ_FLUSH) {
-		/* complete ongoing async transfer before issuing flush */
-		if (card->host->areq)
-			mmc_blk_issue_rw_rq(mq, NULL);
-		ret = mmc_blk_issue_flush(mq, req);
-	} else {
+			break;
+		case REQ_DISCARD | REQ_SECURE:
+			/* complete ongoing async transfer before issuing discard */
+			if (card->host->areq)
+				mmc_blk_issue_rw_rq(mq, NULL);
+			ret = mmc_blk_issue_secdiscard_rq(mq, req);
+			break;
+		case REQ_FLUSH:
+			/* complete ongoing async transfer before issuing discard */
+			if (card->host->areq)
+				mmc_blk_issue_rw_rq(mq, NULL);
+			ret = mmc_blk_issue_flush(mq, req);
+			break;
+		}
+	}		
+	else
 		ret = mmc_blk_issue_rw_rq(mq, req);
-	}
-
+			
 out:
 	if (!req)
 		/* release host only when there are no more requests */
-- 
1.7.4.4

Re: [PATCH] mmc: Use switch() instead of if/else if in mmc_blk_issue_rq.

[Chris Ball]

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@gmail.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@laptop.org>   <http://printf.net/>
One Laptop Per Child