linux-kernel - [RFC 3/4] net/fib: Check budget before should

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Date:   Tue, 26 Mar 2019 15:30:24 +0000
From:   Dmitry Safonov <dima@...sta.com>
To:     linux-kernel@...r.kernel.org
Cc:     Dmitry Safonov <dima@...sta.com>,
        Alexander Duyck <alexander.h.duyck@...ux.intel.com>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        David Ahern <dsahern@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Ido Schimmel <idosch@...lanox.com>, netdev@...r.kernel.org
Subject: [RFC 3/4] net/fib: Check budget before should_{inflate,halve}()

Those functions are compute-costly, if we're out of budget - better
omit additional computations.

Signed-off-by: Dmitry Safonov <dima@...sta.com>
---
 net/ipv4/fib_trie.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index d90cf9dfd443..2ce2739e7693 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -868,7 +868,7 @@ static struct key_vector *resize(struct trie *t, struct key_vector *tn,
 	/* Double as long as the resulting node has a number of
 	 * nonempty nodes that are above the threshold.
 	 */
-	while (should_inflate(tp, tn) && *budget) {
+	while (*budget && should_inflate(tp, tn)) {
 		tp = inflate(t, tn, budget);
 		if (!tp) {
 #ifdef CONFIG_IP_FIB_TRIE_STATS
@@ -894,7 +894,7 @@ static struct key_vector *resize(struct trie *t, struct key_vector *tn,
 	/* Halve as long as the number of empty children in this
 	 * node is above threshold.
 	 */
-	while (should_halve(tp, tn) && *budget) {
+	while (*budget && should_halve(tp, tn)) {
 		tp = halve(t, tn, budget);
 		if (!tp) {
 #ifdef CONFIG_IP_FIB_TRIE_STATS
-- 
2.21.0