| Message ID | 20200120100456.45609-1-wenyang@linux.alibaba.com |
|---|---|
| State | Accepted |
| Delegated to: | David Miller |
| Headers | show |
| Series | tcp_bbr: improve arithmetic division in bbr_update_bw() | expand |
On 1/20/20 2:04 AM, Wen Yang wrote: > 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: Eric Dumazet <edumazet@google.com> Thanks !
From: Wen Yang <wenyang@linux.alibaba.com> Date: Mon, 20 Jan 2020 18:04:56 +0800 > 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> Applied, thank you.
diff --git a/net/ipv4/tcp_bbr.c b/net/ipv4/tcp_bbr.c index a6545ef0d27b..6c4d79baff26 100644 --- a/net/ipv4/tcp_bbr.c +++ b/net/ipv4/tcp_bbr.c @@ -779,8 +779,7 @@ static void bbr_update_bw(struct sock *sk, const struct rate_sample *rs) * 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
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 --- net/ipv4/tcp_bbr.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)