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authorPatrick McHardy <kaber@trash.net>2007-04-09 11:47:18 -0700
committerDavid S. Miller <davem@sunset.davemloft.net>2007-04-25 22:28:38 -0700
commitc5c2523893747f88a83376abad310c8ad13f7197 (patch)
tree58f1ab25ac9f7ca7460abbd24e9bab9c8683f6fd /net/ipv6/esp6.c
parent557922584d9c5b6b990bcfb2fec3134f0e73a05d (diff)
downloadlinux-2.6.38-lt-ux500-c5c2523893747f88a83376abad310c8ad13f7197.tar.gz
[XFRM]: Optimize MTU calculation
Replace the probing based MTU estimation, which usually takes 2-3 iterations to find a fitting value and may underestimate the MTU, by an exact calculation. Also fix underestimation of the XFRM trailer_len, which causes unnecessary reallocations. Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6/esp6.c')
-rw-r--r--net/ipv6/esp6.c22
1 files changed, 12 insertions, 10 deletions
diff --git a/net/ipv6/esp6.c b/net/ipv6/esp6.c
index 6b76c4c3113..7107bb7e2e6 100644
--- a/net/ipv6/esp6.c
+++ b/net/ipv6/esp6.c
@@ -235,22 +235,24 @@ out:
return ret;
}
-static u32 esp6_get_max_size(struct xfrm_state *x, int mtu)
+static u32 esp6_get_mtu(struct xfrm_state *x, int mtu)
{
struct esp_data *esp = x->data;
u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
+ u32 align = max_t(u32, blksize, esp->conf.padlen);
+ u32 rem;
- if (x->props.mode == XFRM_MODE_TUNNEL) {
- mtu = ALIGN(mtu + 2, blksize);
- } else {
- /* The worst case. */
+ mtu -= x->props.header_len + esp->auth.icv_trunc_len;
+ rem = mtu & (align - 1);
+ mtu &= ~(align - 1);
+
+ if (x->props.mode != XFRM_MODE_TUNNEL) {
u32 padsize = ((blksize - 1) & 7) + 1;
- mtu = ALIGN(mtu + 2, padsize) + blksize - padsize;
+ mtu -= blksize - padsize;
+ mtu += min_t(u32, blksize - padsize, rem);
}
- if (esp->conf.padlen)
- mtu = ALIGN(mtu, esp->conf.padlen);
- return mtu + x->props.header_len + esp->auth.icv_trunc_len;
+ return mtu - 2;
}
static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
@@ -380,7 +382,7 @@ static struct xfrm_type esp6_type =
.proto = IPPROTO_ESP,
.init_state = esp6_init_state,
.destructor = esp6_destroy,
- .get_max_size = esp6_get_max_size,
+ .get_mtu = esp6_get_mtu,
.input = esp6_input,
.output = esp6_output,
.hdr_offset = xfrm6_find_1stfragopt,