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netfilter 12/41: xt_physdev: unfold two loops in physdev_mt()

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From: Patrick McHardy
Subject: netfilter 12/41: xt_physdev: unfold two loops in physdev_mt()
Date: Tuesday, March 24, 2009 - 7:03 am

commit eacc17fb64f03b6c268aaf6cea320100d19d8af5
Author: Eric Dumazet <dada1@cosmosbay.com>
Date:   Thu Feb 19 11:17:17 2009 +0100

    netfilter: xt_physdev: unfold two loops in physdev_mt()
    
    xt_physdev netfilter module can use an ifname_compare() helper
    so that two loops are unfolded.
    
    Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
    Signed-off-by: Patrick McHardy <kaber@trash.net>

diff --git a/net/netfilter/xt_physdev.c b/net/netfilter/xt_physdev.c
index 4b13ef7..44a234e 100644
--- a/net/netfilter/xt_physdev.c
+++ b/net/netfilter/xt_physdev.c
@@ -20,10 +20,27 @@ MODULE_DESCRIPTION("Xtables: Bridge physical device match");
 MODULE_ALIAS("ipt_physdev");
 MODULE_ALIAS("ip6t_physdev");
 
+static unsigned long ifname_compare(const char *_a, const char *_b, const char *_mask)
+{
+	const unsigned long *a = (const unsigned long *)_a;
+	const unsigned long *b = (const unsigned long *)_b;
+	const unsigned long *mask = (const unsigned long *)_mask;
+	unsigned long ret;
+
+	ret = (a[0] ^ b[0]) & mask[0];
+	if (IFNAMSIZ > sizeof(unsigned long))
+		ret |= (a[1] ^ b[1]) & mask[1];
+	if (IFNAMSIZ > 2 * sizeof(unsigned long))
+		ret |= (a[2] ^ b[2]) & mask[2];
+	if (IFNAMSIZ > 3 * sizeof(unsigned long))
+		ret |= (a[3] ^ b[3]) & mask[3];
+	BUILD_BUG_ON(IFNAMSIZ > 4 * sizeof(unsigned long));
+	return ret;
+}
+
 static bool
 physdev_mt(const struct sk_buff *skb, const struct xt_match_param *par)
 {
-	int i;
 	static const char nulldevname[IFNAMSIZ] __attribute__((aligned(sizeof(long))));
 	const struct xt_physdev_info *info = par->matchinfo;
 	unsigned long ret;
@@ -68,11 +85,7 @@ physdev_mt(const struct sk_buff *skb, const struct xt_match_param *par)
 	if (!(info->bitmask & XT_PHYSDEV_OP_IN))
 		goto match_outdev;
 	indev = nf_bridge->physindev ? nf_bridge->physindev->name : nulldevname;
-	for (i = 0, ret = 0; i < IFNAMSIZ/sizeof(unsigned long); i++) {
-		ret |= (((const unsigned long *)indev)[i]
-			^ ((const unsigned long ...
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Previous thread: netfilter 07/41: arp_tables: unfold two critical loops in arp_packet_match() by Patrick McHardy on Tuesday, March 24, 2009 - 7:03 am. (13 messages)

Next thread: netfilter 30/41: auto-load ip6_queue module when socket opened by Patrick McHardy on Tuesday, March 24, 2009 - 7:03 am. (1 message)