| From foo@baz Mon 27 Jan 2020 04:06:27 PM CET |
| From: Wen Yang <wenyang@linux.alibaba.com> |
| Date: Mon, 20 Jan 2020 18:04:56 +0800 |
| Subject: tcp_bbr: improve arithmetic division in bbr_update_bw() |
| |
| 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 |
