50 lines
1.6 KiB
Diff
50 lines
1.6 KiB
Diff
From b6bd33114e63d96f424c8e2baf46b3a58745077b Mon Sep 17 00:00:00 2001
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From: Eric Dumazet <eric.dumazet@gmail.com>
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Date: Tue, 7 Dec 2010 12:03:55 +0000
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Subject: tcp: avoid a possible divide by zero
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From: Eric Dumazet <eric.dumazet@gmail.com>
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[ Upstream commit ad9f4f50fe9288bbe65b7dfd76d8820afac6a24c ]
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[ trivial backport to 2.6.34 ]
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sysctl_tcp_tso_win_divisor might be set to zero while one cpu runs in
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tcp_tso_should_defer(). Make sure we dont allow a divide by zero by
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reading sysctl_tcp_tso_win_divisor exactly once.
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Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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---
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net/ipv4/tcp_output.c | 6 ++++--
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1 file changed, 4 insertions(+), 2 deletions(-)
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--- a/net/ipv4/tcp_output.c
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+++ b/net/ipv4/tcp_output.c
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@@ -1518,6 +1518,7 @@ static int tcp_tso_should_defer(struct s
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struct tcp_sock *tp = tcp_sk(sk);
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const struct inet_connection_sock *icsk = inet_csk(sk);
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u32 send_win, cong_win, limit, in_flight;
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+ int win_divisor;
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if (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN)
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goto send_now;
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@@ -1549,13 +1550,14 @@ static int tcp_tso_should_defer(struct s
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if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len))
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goto send_now;
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- if (sysctl_tcp_tso_win_divisor) {
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+ win_divisor = ACCESS_ONCE(sysctl_tcp_tso_win_divisor);
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+ if (win_divisor) {
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u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache);
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/* If at least some fraction of a window is available,
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* just use it.
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*/
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- chunk /= sysctl_tcp_tso_win_divisor;
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+ chunk /= win_divisor;
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if (limit >= chunk)
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goto send_now;
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} else {
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