diff options
| author | Eric Dumazet <eric.dumazet@gmail.com> | 2010-12-07 12:03:55 +0000 |
|---|---|---|
| committer | AK <andi@firstfloor.org> | 2011-02-06 11:03:34 -0800 |
| commit | d98450d683e13c6af7b5219af44cea2671dc07ea (patch) | |
| tree | 1f4f0de2fae5814a3719d5becd52fe12d4d0af3a /net | |
| parent | 9a4b8e0c3674f6506c5a2b3c7ac5ea37e297c0a0 (diff) | |
tcp: avoid a possible divide by zero
[ Upstream commit ad9f4f50fe9288bbe65b7dfd76d8820afac6a24c ]
sysctl_tcp_tso_win_divisor might be set to zero while one cpu runs in
tcp_tso_should_defer(). Make sure we dont allow a divide by zero by
reading sysctl_tcp_tso_win_divisor exactly once.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/tcp_output.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 0c93b0b98b14..a01a6adc8609 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -1516,6 +1516,7 @@ static int tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb) struct tcp_sock *tp = tcp_sk(sk); const struct inet_connection_sock *icsk = inet_csk(sk); u32 send_win, cong_win, limit, in_flight; + int win_divisor; if (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN) goto send_now; @@ -1547,13 +1548,14 @@ static int tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb) if ((skb != tcp_write_queue_tail(sk)) && (limit >= skb->len)) goto send_now; - if (sysctl_tcp_tso_win_divisor) { + win_divisor = ACCESS_ONCE(sysctl_tcp_tso_win_divisor); + if (win_divisor) { u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache); /* If at least some fraction of a window is available, * just use it. */ - chunk /= sysctl_tcp_tso_win_divisor; + chunk /= win_divisor; if (limit >= chunk) goto send_now; } else { |