| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.9 240/271] tcp_bbr: improve arithmetic division in bbr_update_bw() | Date | Tue, 28 Jan 2020 15:06:29 +0100 |
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From: Wen Yang <wenyang@linux.alibaba.com>
[ Upstream commit 5b2f1f3070b6447b76174ea8bfb7390dc6253ebd ]
do_div() does a 64-by-32 division. Use div64_long() instead of it if the divisor is long, to avoid truncation to 32-bit. And as a nice side effect also cleans up the function a bit.
Signed-off-by: Wen Yang <wenyang@linux.alibaba.com> Cc: Eric Dumazet <edumazet@google.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru> Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org> Cc: netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/ipv4/tcp_bbr.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
--- a/net/ipv4/tcp_bbr.c +++ b/net/ipv4/tcp_bbr.c @@ -649,8 +649,7 @@ static void bbr_update_bw(struct sock *s * bandwidth sample. Delivered is in packets and interval_us in uS and * ratio will be <<1 for most connections. So delivered is first scaled. */ - bw = (u64)rs->delivered * BW_UNIT; - do_div(bw, rs->interval_us); + bw = div64_long((u64)rs->delivered * BW_UNIT, rs->interval_us); /* If this sample is application-limited, it is likely to have a very * low delivered count that represents application behavior rather than
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