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authorPavel Begunkov <asml.silence@gmail.com>2022-07-12 21:52:31 +0100
committerJakub Kicinski <kuba@kernel.org>2022-07-19 14:20:54 -0700
commit753f1ca4e1e50248a1b760c9774d6d6b354562cc (patch)
tree2d424a8b10b6dce562b451787136367a6ad7371c /net/core
parentebe73a284f4de8c5d401adeccd9b8fe3183b6e95 (diff)
net: introduce managed frags infrastructure
Some users like io_uring can do page pinning more efficiently, so we want a way to delegate referencing to other subsystems. For that add a new flag called SKBFL_MANAGED_FRAG_REFS. When set, skb doesn't hold page references and upper layers are responsivle to managing page lifetime. It's allowed to convert skbs from managed to normal by calling skb_zcopy_downgrade_managed(). The function will take all needed page references and clear the flag. It's needed, for instance, to avoid mixing managed modes. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/core')
-rw-r--r--net/core/skbuff.c29
1 files changed, 27 insertions, 2 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index f5a3ebbc1f7e..cf4107d80bc4 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -666,11 +666,18 @@ static void skb_release_data(struct sk_buff *skb)
&shinfo->dataref))
goto exit;
- skb_zcopy_clear(skb, true);
+ if (skb_zcopy(skb)) {
+ bool skip_unref = shinfo->flags & SKBFL_MANAGED_FRAG_REFS;
+
+ skb_zcopy_clear(skb, true);
+ if (skip_unref)
+ goto free_head;
+ }
for (i = 0; i < shinfo->nr_frags; i++)
__skb_frag_unref(&shinfo->frags[i], skb->pp_recycle);
+free_head:
if (shinfo->frag_list)
kfree_skb_list(shinfo->frag_list);
@@ -895,7 +902,10 @@ EXPORT_SYMBOL(skb_dump);
*/
void skb_tx_error(struct sk_buff *skb)
{
- skb_zcopy_clear(skb, true);
+ if (skb) {
+ skb_zcopy_downgrade_managed(skb);
+ skb_zcopy_clear(skb, true);
+ }
}
EXPORT_SYMBOL(skb_tx_error);
@@ -1375,6 +1385,16 @@ int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb,
}
EXPORT_SYMBOL_GPL(skb_zerocopy_iter_stream);
+void __skb_zcopy_downgrade_managed(struct sk_buff *skb)
+{
+ int i;
+
+ skb_shinfo(skb)->flags &= ~SKBFL_MANAGED_FRAG_REFS;
+ for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
+ skb_frag_ref(skb, i);
+}
+EXPORT_SYMBOL_GPL(__skb_zcopy_downgrade_managed);
+
static int skb_zerocopy_clone(struct sk_buff *nskb, struct sk_buff *orig,
gfp_t gfp_mask)
{
@@ -1692,6 +1712,8 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
BUG_ON(skb_shared(skb));
+ skb_zcopy_downgrade_managed(skb);
+
size = SKB_DATA_ALIGN(size);
if (skb_pfmemalloc(skb))
@@ -3488,6 +3510,8 @@ void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len)
int pos = skb_headlen(skb);
const int zc_flags = SKBFL_SHARED_FRAG | SKBFL_PURE_ZEROCOPY;
+ skb_zcopy_downgrade_managed(skb);
+
skb_shinfo(skb1)->flags |= skb_shinfo(skb)->flags & zc_flags;
skb_zerocopy_clone(skb1, skb, 0);
if (len < pos) /* Split line is inside header. */
@@ -3841,6 +3865,7 @@ int skb_append_pagefrags(struct sk_buff *skb, struct page *page,
if (skb_can_coalesce(skb, i, page, offset)) {
skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], size);
} else if (i < MAX_SKB_FRAGS) {
+ skb_zcopy_downgrade_managed(skb);
get_page(page);
skb_fill_page_desc(skb, i, page, offset, size);
} else {