net: generalize sk_alloc_sg to work with scatterlist rings
The current implementation of sk_alloc_sg expects scatterlist to always
start at entry 0 and complete at entry MAX_SKB_FRAGS.
Future patches will want to support starting at arbitrary offset into
scatterlist so add an additional sg_start parameters and then default
to the current values in TLS code paths.
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
diff --git a/net/core/sock.c b/net/core/sock.c
index f68dff0..4f92c29 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2240,19 +2240,20 @@ bool sk_page_frag_refill(struct sock *sk, struct page_frag *pfrag)
EXPORT_SYMBOL(sk_page_frag_refill);
int sk_alloc_sg(struct sock *sk, int len, struct scatterlist *sg,
- int *sg_num_elem, unsigned int *sg_size,
+ int sg_start, int *sg_curr_index, unsigned int *sg_curr_size,
int first_coalesce)
{
+ int sg_curr = *sg_curr_index, use = 0, rc = 0;
+ unsigned int size = *sg_curr_size;
struct page_frag *pfrag;
- unsigned int size = *sg_size;
- int num_elem = *sg_num_elem, use = 0, rc = 0;
struct scatterlist *sge;
- unsigned int orig_offset;
len -= size;
pfrag = sk_page_frag(sk);
while (len > 0) {
+ unsigned int orig_offset;
+
if (!sk_page_frag_refill(sk, pfrag)) {
rc = -ENOMEM;
goto out;
@@ -2270,17 +2271,21 @@ int sk_alloc_sg(struct sock *sk, int len, struct scatterlist *sg,
orig_offset = pfrag->offset;
pfrag->offset += use;
- sge = sg + num_elem - 1;
- if (num_elem > first_coalesce && sg_page(sg) == pfrag->page &&
+ sge = sg + sg_curr - 1;
+ if (sg_curr > first_coalesce && sg_page(sg) == pfrag->page &&
sg->offset + sg->length == orig_offset) {
sg->length += use;
} else {
- sge++;
+ sge = sg + sg_curr;
sg_unmark_end(sge);
sg_set_page(sge, pfrag->page, use, orig_offset);
get_page(pfrag->page);
- ++num_elem;
- if (num_elem == MAX_SKB_FRAGS) {
+ sg_curr++;
+
+ if (sg_curr == MAX_SKB_FRAGS)
+ sg_curr = 0;
+
+ if (sg_curr == sg_start) {
rc = -ENOSPC;
break;
}
@@ -2289,8 +2294,8 @@ int sk_alloc_sg(struct sock *sk, int len, struct scatterlist *sg,
len -= use;
}
out:
- *sg_size = size;
- *sg_num_elem = num_elem;
+ *sg_curr_size = size;
+ *sg_curr_index = sg_curr;
return rc;
}
EXPORT_SYMBOL(sk_alloc_sg);