diff options
| author | Eric Dumazet <eric.dumazet@gmail.com> | 2010-12-07 12:03:55 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2010-12-08 12:34:08 -0800 |
| commit | ad9f4f50fe9288bbe65b7dfd76d8820afac6a24c (patch) | |
| tree | f3f3100da8d042607bbbab31c1f8a060ba2b5f15 /net/ipv4/tcp_output.c | |
| parent | c7757fdb41dfcf6add9f8a4576eb85aa5e77a4eb (diff) | |
| download | lwn-ad9f4f50fe9288bbe65b7dfd76d8820afac6a24c.tar.gz lwn-ad9f4f50fe9288bbe65b7dfd76d8820afac6a24c.zip | |
tcp: avoid a possible divide by zero
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>
Diffstat (limited to 'net/ipv4/tcp_output.c')
| -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 3c59ab42df2b..0d4a3cebfb46 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -1512,6 +1512,7 @@ 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 & TCPHDR_FIN) goto send_now; @@ -1543,13 +1544,14 @@ 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 { |