Il 03/09/2014 06:29, Rusty Russell ha scritto: > + sg_init_table(rq->sg, MAX_SKB_FRAGS + 2);
I think 2 is enough here. That said... > sg_set_buf(rq->sg, &hdr->hdr, sizeof hdr->hdr); > - > skb_to_sgvec(skb, rq->sg + 1, 0, skb->len); > > err = virtqueue_add_inbuf(rq->vq, rq->sg, 2, skb, gfp); ... skb_to_sgvec will already make the sg well formed, so the sg_init_table is _almost_ redundant; it is only there to remove intermediate end marks. The block layer takes care to remove them, but skb_to_sgvec doesn't. If the following patch can be accepted to net/core/skbuff.c, the sg_init_table in virtnet_alloc_queues will suffice. Paolo -------------------- 8< ------------------- From: Paolo Bonzini <[email protected]> Subject: [PATCH] net: skb_to_sgvec: do not leave intermediate marks in the sgvec sg_set_buf/sg_set_page will leave the end mark in place in their argument, which may be in the middle of a scatterlist. If we remove the mark before calling them, we can avoid calls to sg_init_table before skb_to_sgvec. However, users of skb_to_sgvec_nomark now need to be careful and possibly restore the mark. Signed-off-by: Paolo Bonzini <[email protected]> diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 163b673f9e62..a3108ef1f1c0 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -3265,6 +3265,7 @@ __skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len) if (copy > 0) { if (copy > len) copy = len; + sg_unmark_end(sg); sg_set_buf(sg, skb->data + offset, copy); elt++; if ((len -= copy) == 0) @@ -3283,6 +3284,7 @@ __skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len) if (copy > len) copy = len; + sg_unmark_end(&sg[elt]); sg_set_page(&sg[elt], skb_frag_page(frag), copy, frag->page_offset+offset-start); elt++; @@ -3322,7 +3324,7 @@ __skb_to_sgvec(struct sk_buff *skb, struct scatterlist *sg, int offset, int len) * Scenario to use skb_to_sgvec_nomark: * 1. sg_init_table * 2. skb_to_sgvec_nomark(payload1) - * 3. skb_to_sgvec_nomark(payload2) + * 3. skb_to_sgvec(payload2) * * This is equivalent to: * 1. sg_init_table diff --git a/net/ipv4/ah4.c b/net/ipv4/ah4.c index a2afa89513a0..9ae5756d9e5f 100644 --- a/net/ipv4/ah4.c +++ b/net/ipv4/ah4.c @@ -227,6 +227,7 @@ static int ah_output(struct xfrm_state *x, struct sk_buff *skb) *seqhi = htonl(XFRM_SKB_CB(skb)->seq.output.hi); sg_set_buf(seqhisg, seqhi, seqhi_len); } + sg_mark_end(&sg[nfrags + sglists]); ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len); ahash_request_set_callback(req, 0, ah_output_done, skb); @@ -395,6 +396,7 @@ static int ah_input(struct xfrm_state *x, struct sk_buff *skb) *seqhi = XFRM_SKB_CB(skb)->seq.input.hi; sg_set_buf(seqhisg, seqhi, seqhi_len); } + sg_mark_end(&sg[nfrags + sglists]); ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len); ahash_request_set_callback(req, 0, ah_input_done, skb); diff --git a/net/ipv6/ah6.c b/net/ipv6/ah6.c index 72a4930bdc0a..c680d82e43de 100644 --- a/net/ipv6/ah6.c +++ b/net/ipv6/ah6.c @@ -430,6 +430,8 @@ static int ah6_output(struct xfrm_state *x, struct sk_buff *skb) *seqhi = htonl(XFRM_SKB_CB(skb)->seq.output.hi); sg_set_buf(seqhisg, seqhi, seqhi_len); } + sg_mark_end(&sg[nfrags + sglists]); + ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len); ahash_request_set_callback(req, 0, ah6_output_done, skb); @@ -608,6 +610,7 @@ static int ah6_input(struct xfrm_state *x, struct sk_buff *skb) *seqhi = XFRM_SKB_CB(skb)->seq.input.hi; sg_set_buf(seqhisg, seqhi, seqhi_len); } + sg_mark_end(&sg[nfrags + sglists]); ahash_request_set_crypt(req, sg, icv, skb->len + seqhi_len); ahash_request_set_callback(req, 0, ah6_input_done, skb); _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
