netdev - [PATCH net] net:sysctl fix the confusing corner of tcp

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Message-ID: <1449626509-3736-1-git-send-email-wangyufen@huawei.com>
Date:	Wed, 9 Dec 2015 10:01:49 +0800
From:	Wang Yufen <wangyufen@...wei.com>
To:	<davem@...emloft.net>, <netdev@...r.kernel.org>
CC:	<guohanjun@...wei.com>, <zhangdianfang@...wei.com>,
	<dingtianhong@...wei.com>, <huxinwei@...wei.com>,
	Yufen Wang <wangyufen@...wei.com>,
	Eric Dumazet <eric.dumazet@...il.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>
Subject: [PATCH net] net:sysctl fix the confusing corner of tcp_mem

From: Yufen Wang <wangyufen@...wei.com>

I tried on linux-4.1:
    linux:~# cat /proc/sys/net/ipv4/tcp_mem 
    8388608	12582912	16777216
    linux:~# echo 1234 >/proc/sys/net/ipv4/tcp_mem 
    -bash: echo: write error: Invalid argument
    linux:~# cat /proc/sys/net/ipv4/tcp_mem 
    1234	12582912	16777216

the echo operation got error, but value already written to tcp_mem.
If a write() returns an error like EINVAL, we expect no change occurred.
This patch fix the confusing corner and makes __do_proc_doulongvec_minmax 
works the same as __do_proc_dointvec

Signed-off-by: Yufen Wang <wangyufen@...wei.com>
Cc: Eric Dumazet <eric.dumazet@...il.com>
Cc: "Eric W. Biederman" <ebiederm@...ssion.com>
---
 kernel/sysctl.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index c3eee4c..e3ee4be 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2318,6 +2318,8 @@ static int __do_proc_doulongvec_minmax(void *data, struct ctl_table *table, int
 			bool neg;
 
 			left -= proc_skip_spaces(&kbuf);
+                        if (!left)
+                                break;
 
 			err = proc_get_long(&kbuf, &left, &val, &neg,
 					     proc_wspace_sep,
-- 
2.5.0


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