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Commit 57d3e48b authored by Wen Yang's avatar Wen Yang Committed by Greg Kroah-Hartman
Browse files

tcp_bbr: improve arithmetic division in bbr_update_bw() 



[ 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: default avatarWen 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: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 627996d4

net/ipv4/tcp_bbr.c

+1 −2
Original line number Diff line number Diff line
@@ -649,8 +649,7 @@ 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