linux-kernel - [PATCH] md/raid5: eliminate if-statements in cmp

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Date:   Sun,  3 Sep 2023 17:50:59 +0800
From:   Kuan-Wei Chiu <visitorckw@...il.com>
To:     song@...nel.org
Cc:     linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org,
        Kuan-Wei Chiu <visitorckw@...il.com>
Subject: [PATCH] md/raid5: eliminate if-statements in cmp_stripe()

Replace the conditional statements in the cmp_stripe() function with a
branchless version to improve code readability and potentially enhance
performance. The new code calculates the result using a subtraction of
comparison results, making it more concise and avoiding conditional
branches. This change does not alter the functionality of the code.

Signed-off-by: Kuan-Wei Chiu <visitorckw@...il.com>
---
 drivers/md/raid5.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 4cb9c608ee19..b14d7ba38f0f 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -1035,11 +1035,7 @@ static int cmp_stripe(void *priv, const struct list_head *a,
 				struct r5pending_data, sibling);
 	const struct r5pending_data *db = list_entry(b,
 				struct r5pending_data, sibling);
-	if (da->sector > db->sector)
-		return 1;
-	if (da->sector < db->sector)
-		return -1;
-	return 0;
+	return (da->sector > db->sector) - (da->sector < db->sector);
 }
 
 static void dispatch_defer_bios(struct r5conf *conf, int target,
-- 
2.25.1