netdev - [PATCH] net: avoid the unnecessary kmalloc

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-Id: <1291047392-3057-1-git-send-email-xiaosuo@gmail.com>
Date:	Tue, 30 Nov 2010 00:16:32 +0800
From:	Changli Gao <xiaosuo@...il.com>
To:	"David S. Miller" <davem@...emloft.net>
Cc:	netdev@...r.kernel.org, Changli Gao <xiaosuo@...il.com>
Subject: [PATCH] net: avoid the unnecessary kmalloc

If the old memory allocated by kmalloc() is larger than the new requested,
pskb_expand_head() doesn't need to allocate a new one, unless the skb is
cloned.

Signed-off-by: Changli Gao <xiaosuo@...il.com>
---
 net/core/skbuff.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 104f844..3908329 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -778,6 +778,17 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
 
 	size = SKB_DATA_ALIGN(size);
 
+	if (!skb->cloned &&
+	    size + sizeof(struct skb_shared_info) <= ksize(skb->head)) {
+		memmove(skb->head + size, skb_shinfo(skb),
+			offsetof(struct skb_shared_info,
+				 frags[skb_shinfo(skb)->nr_frags]));
+		memmove(skb->head + nhead, skb->head,
+			skb_tail_pointer(skb) - skb->head);
+		off = nhead;
+		goto adjust_others;
+	}
+
 	data = kmalloc(size + sizeof(struct skb_shared_info), gfp_mask);
 	if (!data)
 		goto nodata;
@@ -816,6 +827,7 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
 	off = (data + nhead) - skb->head;
 
 	skb->head     = data;
+adjust_others:
 	skb->data    += off;
 #ifdef NET_SKBUFF_DATA_USES_OFFSET
 	skb->end      = size;
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html