linux-kernel - [PATCH] iov_iter: Fix repeated minus operation

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Message-Id: <1657707820-124858-1-git-send-email-liuxp11@chinatelecom.cn>
Date:   Wed, 13 Jul 2022 18:23:40 +0800
From:   Liu Xinpeng <liuxp11@...natelecom.cn>
To:     viro@...iv.linux.org.uk
Cc:     linux-kernel@...r.kernel.org, Liu Xinpeng <liuxp11@...natelecom.cn>
Subject: [PATCH] iov_iter: Fix repeated minus operation

After executing command 'cat /proc/cpuinfo', got a message:

[    6.909745] ------------[ cut here ]------------
[    6.910267] WARNING: CPU: 0 PID: 76 at lib/iov_iter.c:1026
iov_iter_pipe+0x34/0x40
[    6.910951] Modules linked in:
[    6.911584] CPU: 0 PID: 76 Comm: cat Not tainted 5.19.0-rc6-next-20220711 #9
[    6.911916] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
[    6.912668] RIP: 0010:iov_iter_pipe+0x34/0x40
[    6.913062] Code: 72 54 39 72 5c 76 23 48 c7 07 00 00 00 00 48 c7 47 08 00 00
00 00 c6 07 03 48 89 4f 10 48 89 57 18 89 47 20 89 47 24 c3 0f 0b <0f> 7
[    6.914341] RSP: 0018:ffffc900001c7d48 EFLAGS: 00000246
[    6.914647] RAX: 0000000000000010 RBX: ffff888004988700 RCX: 0000000000000000
[    6.914893] RDX: ffff88800490bc00 RSI: 0000000000000010 RDI: ffffc900001c7d58
[    6.915302] RBP: ffffc900001c7e00 R08: 0000000000000000 R09: ffff888004cafad8
[    6.915609] R10: 0000000000020000 R11: 0000000000001000 R12: ffff88800490bc00
[    6.915856] R13: ffffc900001c7e48 R14: 00000000000002d5 R15: ffff88800490bc00
[    6.916352] FS:  00000000016df8c0(0000) GS:ffff88800f600000(0000)

Checking the code, need to delete the duplicate minus in a loop.

Signed-off-by: Liu Xinpeng <liuxp11@...natelecom.cn>
---
 lib/iov_iter.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 4a3451e..642841ce 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -472,7 +472,6 @@ static size_t copy_pipe_to_iter(const void *addr, size_t bytes,
 			break;
 		memcpy_to_page(page, off, addr, chunk);
 		addr += chunk;
-		n -= chunk;
 	}
 	return bytes;
 }
-- 
1.8.3.1