Messages in this thread Patch in this message | | | Date | Wed, 12 Dec 2007 22:53:06 -0800 | From | Greg KH <> | Subject | [patch 42/60] TCP: Problem bug with sysctl_tcp_congestion_control function |
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2.6.23-stable review patch. If anyone has any objections, please let us know.
------------------ From: Sam Jansen <sjansen@google.com>
[TCP]: Problem bug with sysctl_tcp_congestion_control function
[ Upstream commit: 5487796f0c9475586277a0a7a91211ce5746fa6a ]
sysctl_tcp_congestion_control seems to have a bug that prevents it from actually calling the tcp_set_default_congestion_control function. This is not so apparent because it does not return an error and generally the /proc interface is used to configure the default TCP congestion control algorithm. This is present in 2.6.18 onwards and probably earlier, though I have not inspected 2.6.15--2.6.17.
sysctl_tcp_congestion_control calls sysctl_string and expects a successful return code of 0. In such a case it actually sets the congestion control algorithm with tcp_set_default_congestion_control. Otherwise, it returns the value returned by sysctl_string. This was correct in 2.6.14, as sysctl_string returned 0 on success. However, sysctl_string was updated to return 1 on success around about 2.6.15 and sysctl_tcp_congestion_control was not updated. Even though sysctl_tcp_congestion_control returns 1, do_sysctl_strategy converts this return code to '0', so the caller never notices the error.
Signed-off-by: David S. Miller <davem@davemloft.net> Cc: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- net/ipv4/sysctl_net_ipv4.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/net/ipv4/sysctl_net_ipv4.c +++ b/net/ipv4/sysctl_net_ipv4.c @@ -121,7 +121,7 @@ static int sysctl_tcp_congestion_control tcp_get_default_congestion_control(val); ret = sysctl_string(&tbl, name, nlen, oldval, oldlenp, newval, newlen); - if (ret == 0 && newval && newlen) + if (ret == 1 && newval && newlen) ret = tcp_set_default_congestion_control(val); return ret; } --
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