Re: [PATCH] netfilter: use krealloc() in nf_conntrack_extend.c V2

From: Patrick McHardy
Date: Thu May 22 2008 - 15:08:09 EST

Pekka J Enberg wrote:
The ksize() API is going away because it is being abused and it doesn't even
work consistenly across different allocators. Therefore, convert
net/netfilter/nf_conntrack_extend.c to use krealloc().

Cc: <netfilter-devel@xxxxxxxxxxxxxxx>
Cc: <netdev@xxxxxxxxxxxxxxx>
Cc: Matt Mackall <mpm@xxxxxxxxxxx>
Cc: Christoph Lameter <clameter@xxxxxxx>
Signed-off-by: Pekka Enberg <penberg@xxxxxxxxxxxxxx>
Patrick, please use this patch instead. The previous one did the moving
unconditionally which is wrong. This one moves entries around only if
krealloc() allocated a new buffer.

net/netfilter/nf_conntrack_extend.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)

Index: slab-2.6/net/netfilter/nf_conntrack_extend.c
--- slab-2.6.orig/net/netfilter/nf_conntrack_extend.c 2008-05-22 21:52:12.000000000 +0300
+++ slab-2.6/net/netfilter/nf_conntrack_extend.c 2008-05-22 21:52:26.000000000 +0300
@@ -88,13 +88,11 @@
newlen = newoff + t->len;
- if (newlen >= ksize(ct->ext)) {
- new = kmalloc(newlen, gfp);
- if (!new)
- return NULL;
- memcpy(new, ct->ext, ct->ext->len);
+ new = krealloc(ct->ext, newlen, gfp);

Unfortunately this means we'll always have to reallocate, even
if there's still some room left from the previous allocation.
Any chance to avoid that?

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