linux-kernel - [PATCH] block:Remove extra condition in end of disk check

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Sun, 23 Jun 2013 22:47:11 +0530
From:	Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>
To:	Jens Axboe <axboe@...nel.dk>, LKML <linux-kernel@...r.kernel.org>
Cc:	<raghavendra.kt@...ux.vnet.ibm.com>
Subject: [PATCH] block:Remove extra condition in end of disk check

From: Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>

Since #sector is always positive the reduced condition check
encompasses maxsector < nr_sectors check.

Signed-off-by: Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>
---
An userspace program looping with:
maxsector - 0-9999
nr_sector - 0-999
sector - 0-999 gave 6.4% improvement with new condition though I agree that
it is not the best way to test it perhaps :)

diff --git a/block/blk-core.c b/block/blk-core.c
index 33c33bc..4a78583 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1656,7 +1656,7 @@ static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors)
 	if (maxsector) {
 		sector_t sector = bio->bi_sector;
 
-		if (maxsector < nr_sectors || maxsector - nr_sectors < sector) {
+		if (maxsector - nr_sectors < sector) {
 			/*
 			 * This may well happen - the kernel calls bread()
 			 * without checking the size of the device, e.g., when

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/