netdev - [PATCH 1/2] net: ipv4: Use macro DIV_ROUND

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Date:   Thu, 30 Mar 2017 00:45:11 +0530
From:   Varsha Rao <rvarsha016@...il.com>
To:     netdev@...r.kernel.org
Cc:     outreachy-kernel <outreachy-kernel@...glegroups.com>
Subject: [PATCH 1/2] net: ipv4: Use macro DIV_ROUND_UP.

The macro DIV_ROUND_UP performs the computation (((n) + (d) - 1) /(d)).
It simplifies the divisor calculations. This was done using the following
coccinelle script:

@@
expression e1;
expression e2;
@@
(
- ((e1) + e2 - 1) / (e2)
+ DIV_ROUND_UP(e1,e2)
|
- ((e1) + (e2 - 1)) / (e2)
+ DIV_ROUND_UP(e1,e2)
)

Signed-off-by: Varsha Rao <rvarsha016@...il.com>
---
 net/ipv4/tcp_bbr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/tcp_bbr.c b/net/ipv4/tcp_bbr.c
index b89bce4..4da4bc1 100644
--- a/net/ipv4/tcp_bbr.c
+++ b/net/ipv4/tcp_bbr.c
@@ -314,7 +314,7 @@ static u32 bbr_target_cwnd(struct sock *sk, u32 bw, int gain)
 	w = (u64)bw * bbr->min_rtt_us;

 	/* Apply a gain to the given value, then remove the BW_SCALE shift. */
-	cwnd = (((w * gain) >> BBR_SCALE) + BW_UNIT - 1) / BW_UNIT;
+	cwnd = DIV_ROUND_UP((w * gain) >> BBR_SCALE, BW_UNIT);

 	/* Allow enough full-sized skbs in flight to utilize end systems. */
 	cwnd += 3 * bbr->tso_segs_goal;
-- 
2.9.3