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tcp_bbr: improve arithmetic division in bbr_update_bw() 

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>
This commit is contained in:
Wen Yang 2020-01-20 18:04:56 +08:00 committed by David S. Miller
parent cb626bf566
commit 5b2f1f3070
1 changed files with 1 additions and 2 deletions
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3
net/ipv4/tcp_bbr.c
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@ -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 * bandwidth sample. Delivered is in packets and interval_us in uS and
* ratio will be <<1 for most connections. So delivered is first scaled. * ratio will be <<1 for most connections. So delivered is first scaled.
*/ */
bw = (u64)rs->delivered * BW_UNIT; bw = div64_long((u64)rs->delivered * BW_UNIT, rs->interval_us);
do_div(bw, rs->interval_us);
/* If this sample is application-limited, it is likely to have a very /* If this sample is application-limited, it is likely to have a very
* low delivered count that represents application behavior rather than * low delivered count that represents application behavior rather than