[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>hifive-unleashed-5.1
parent
557922584d
commit
c5c2523893
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@ -279,7 +279,7 @@ struct xfrm_type
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xfrm_address_t *(*local_addr)(struct xfrm_state *, xfrm_address_t *);
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xfrm_address_t *(*local_addr)(struct xfrm_state *, xfrm_address_t *);
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xfrm_address_t *(*remote_addr)(struct xfrm_state *, xfrm_address_t *);
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xfrm_address_t *(*remote_addr)(struct xfrm_state *, xfrm_address_t *);
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/* Estimate maximal size of result of transformation of a dgram */
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/* Estimate maximal size of result of transformation of a dgram */
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u32 (*get_max_size)(struct xfrm_state *, int size);
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u32 (*get_mtu)(struct xfrm_state *, int size);
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};
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};
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extern int xfrm_register_type(struct xfrm_type *type, unsigned short family);
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extern int xfrm_register_type(struct xfrm_type *type, unsigned short family);
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@ -272,32 +272,34 @@ out:
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return -EINVAL;
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return -EINVAL;
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}
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}
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static u32 esp4_get_max_size(struct xfrm_state *x, int mtu)
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static u32 esp4_get_mtu(struct xfrm_state *x, int mtu)
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{
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{
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struct esp_data *esp = x->data;
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struct esp_data *esp = x->data;
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u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
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u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
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int enclen = 0;
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u32 align = max_t(u32, blksize, esp->conf.padlen);
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u32 rem;
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mtu -= x->props.header_len + esp->auth.icv_trunc_len;
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rem = mtu & (align - 1);
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mtu &= ~(align - 1);
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switch (x->props.mode) {
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switch (x->props.mode) {
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case XFRM_MODE_TUNNEL:
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case XFRM_MODE_TUNNEL:
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mtu = ALIGN(mtu +2, blksize);
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break;
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break;
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default:
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default:
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case XFRM_MODE_TRANSPORT:
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case XFRM_MODE_TRANSPORT:
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/* The worst case */
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/* The worst case */
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mtu = ALIGN(mtu + 2, 4) + blksize - 4;
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mtu -= blksize - 4;
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mtu += min_t(u32, blksize - 4, rem);
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break;
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break;
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case XFRM_MODE_BEET:
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case XFRM_MODE_BEET:
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/* The worst case. */
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/* The worst case. */
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enclen = IPV4_BEET_PHMAXLEN;
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mtu -= IPV4_BEET_PHMAXLEN;
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mtu = ALIGN(mtu + enclen + 2, blksize);
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mtu += min_t(u32, IPV4_BEET_PHMAXLEN, rem);
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break;
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break;
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}
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}
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if (esp->conf.padlen)
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return mtu - 2;
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mtu = ALIGN(mtu, esp->conf.padlen);
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return mtu + x->props.header_len + esp->auth.icv_trunc_len - enclen;
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}
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}
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static void esp4_err(struct sk_buff *skb, u32 info)
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static void esp4_err(struct sk_buff *skb, u32 info)
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@ -340,6 +342,7 @@ static int esp_init_state(struct xfrm_state *x)
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{
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{
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struct esp_data *esp = NULL;
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struct esp_data *esp = NULL;
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struct crypto_blkcipher *tfm;
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struct crypto_blkcipher *tfm;
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u32 align;
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/* null auth and encryption can have zero length keys */
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/* null auth and encryption can have zero length keys */
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if (x->aalg) {
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if (x->aalg) {
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@ -421,7 +424,10 @@ static int esp_init_state(struct xfrm_state *x)
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}
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}
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}
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}
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x->data = esp;
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x->data = esp;
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x->props.trailer_len = esp4_get_max_size(x, 0) - x->props.header_len;
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align = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
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if (esp->conf.padlen)
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align = max_t(u32, align, esp->conf.padlen);
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x->props.trailer_len = align + 1 + esp->auth.icv_trunc_len;
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return 0;
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return 0;
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error:
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error:
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@ -438,7 +444,7 @@ static struct xfrm_type esp_type =
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.proto = IPPROTO_ESP,
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.proto = IPPROTO_ESP,
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.init_state = esp_init_state,
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.init_state = esp_init_state,
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.destructor = esp_destroy,
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.destructor = esp_destroy,
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.get_max_size = esp4_get_max_size,
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.get_mtu = esp4_get_mtu,
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.input = esp_input,
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.input = esp_input,
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.output = esp_output
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.output = esp_output
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};
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};
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@ -235,22 +235,24 @@ out:
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return ret;
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return ret;
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}
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}
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static u32 esp6_get_max_size(struct xfrm_state *x, int mtu)
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static u32 esp6_get_mtu(struct xfrm_state *x, int mtu)
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{
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{
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struct esp_data *esp = x->data;
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struct esp_data *esp = x->data;
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u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
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u32 blksize = ALIGN(crypto_blkcipher_blocksize(esp->conf.tfm), 4);
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u32 align = max_t(u32, blksize, esp->conf.padlen);
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u32 rem;
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if (x->props.mode == XFRM_MODE_TUNNEL) {
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mtu -= x->props.header_len + esp->auth.icv_trunc_len;
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mtu = ALIGN(mtu + 2, blksize);
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rem = mtu & (align - 1);
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} else {
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mtu &= ~(align - 1);
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/* The worst case. */
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if (x->props.mode != XFRM_MODE_TUNNEL) {
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u32 padsize = ((blksize - 1) & 7) + 1;
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u32 padsize = ((blksize - 1) & 7) + 1;
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mtu = ALIGN(mtu + 2, padsize) + blksize - padsize;
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mtu -= blksize - padsize;
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mtu += min_t(u32, blksize - padsize, rem);
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}
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}
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if (esp->conf.padlen)
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mtu = ALIGN(mtu, esp->conf.padlen);
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return mtu + x->props.header_len + esp->auth.icv_trunc_len;
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return mtu - 2;
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}
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}
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static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
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static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
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@ -380,7 +382,7 @@ static struct xfrm_type esp6_type =
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.proto = IPPROTO_ESP,
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.proto = IPPROTO_ESP,
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.init_state = esp6_init_state,
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.init_state = esp6_init_state,
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.destructor = esp6_destroy,
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.destructor = esp6_destroy,
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.get_max_size = esp6_get_max_size,
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.get_mtu = esp6_get_mtu,
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.input = esp6_input,
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.input = esp6_input,
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.output = esp6_output,
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.output = esp6_output,
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.hdr_offset = xfrm6_find_1stfragopt,
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.hdr_offset = xfrm6_find_1stfragopt,
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@ -1667,37 +1667,17 @@ void xfrm_state_delete_tunnel(struct xfrm_state *x)
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}
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}
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EXPORT_SYMBOL(xfrm_state_delete_tunnel);
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EXPORT_SYMBOL(xfrm_state_delete_tunnel);
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/*
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* This function is NOT optimal. For example, with ESP it will give an
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* MTU that's usually two bytes short of being optimal. However, it will
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* usually give an answer that's a multiple of 4 provided the input is
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* also a multiple of 4.
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*/
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int xfrm_state_mtu(struct xfrm_state *x, int mtu)
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int xfrm_state_mtu(struct xfrm_state *x, int mtu)
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{
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{
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int res = mtu;
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int res;
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res -= x->props.header_len;
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for (;;) {
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int m = res;
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if (m < 68)
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return 68;
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spin_lock_bh(&x->lock);
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if (x->km.state == XFRM_STATE_VALID &&
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x->type && x->type->get_max_size)
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m = x->type->get_max_size(x, m);
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else
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m += x->props.header_len;
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spin_unlock_bh(&x->lock);
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if (m <= mtu)
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break;
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res -= (m - mtu);
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}
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spin_lock_bh(&x->lock);
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if (x->km.state == XFRM_STATE_VALID &&
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x->type && x->type->get_mtu)
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res = x->type->get_mtu(x, mtu);
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else
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res = mtu;
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spin_unlock_bh(&x->lock);
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return res;
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return res;
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}
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}
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