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Message-ID: <20240306235922.282781-2-almasrymina@google.com>
Date: Wed, 6 Mar 2024 15:59:19 -0800
From: Mina Almasry <almasrymina@...gle.com>
To: netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-rdma@...r.kernel.org
Cc: Mina Almasry <almasrymina@...gle.com>, Mirko Lindner <mlindner@...vell.com>,
Stephen Hemminger <stephen@...workplumber.org>, "David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
Tariq Toukan <tariqt@...dia.com>, Boris Pismenny <borisp@...dia.com>,
John Fastabend <john.fastabend@...il.com>, Dragos Tatulea <dtatulea@...dia.com>
Subject: [RFC PATCH net-next v1 1/2] net: mirror skb frag ref/unref helpers
Refactor some of the skb frag ref/unref helpers for improved clarity.
Implement napi_pp_get_page() to be the mirror counterpart of
napi_pp_put_page().
Implement napi_frag_ref() to be the mirror counterpart of
napi_frag_unref().
Improve __skb_frag_ref() to become a mirror counterpart of
__skb_frag_unref(). Previously unref could handle pp & non-pp pages,
while the ref could only handle non-pp pages. Now both the ref & unref
helpers can correctly handle both pp & non-pp pages.
Now that __skb_frag_ref() can handle both pp & non-pp pages, remove
skb_pp_frag_ref(), and use __skb_frag_ref() instead. This lets us
remove pp specific handling from skb_try_coalesce.
Signed-off-by: Mina Almasry <almasrymina@...gle.com>
---
include/linux/skbuff.h | 24 +++++++++++++++---
net/core/skbuff.c | 56 ++++++++++++++----------------------------
2 files changed, 39 insertions(+), 41 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index d577e0bee18d..51316b0e20bc 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -3477,15 +3477,31 @@ static inline struct page *skb_frag_page(const skb_frag_t *frag)
return netmem_to_page(frag->netmem);
}
+bool napi_pp_get_page(struct page *page);
+
+static inline void napi_frag_ref(skb_frag_t *frag, bool recycle)
+{
+#ifdef CONFIG_PAGE_POOL
+ struct page *page = skb_frag_page(frag);
+
+ if (recycle && napi_pp_get_page(page))
+ return;
+#endif
+ get_page(page);
+}
+
/**
* __skb_frag_ref - take an addition reference on a paged fragment.
* @frag: the paged fragment
+ * @recycle: skb->pp_recycle param of the parent skb.
*
- * Takes an additional reference on the paged fragment @frag.
+ * Takes an additional reference on the paged fragment @frag. Obtains the
+ * correct reference count depending on whether skb->pp_recycle is set and
+ * whether the frag is a page pool frag.
*/
-static inline void __skb_frag_ref(skb_frag_t *frag)
+static inline void __skb_frag_ref(skb_frag_t *frag, bool recycle)
{
- get_page(skb_frag_page(frag));
+ napi_frag_ref(frag, recycle);
}
/**
@@ -3497,7 +3513,7 @@ static inline void __skb_frag_ref(skb_frag_t *frag)
*/
static inline void skb_frag_ref(struct sk_buff *skb, int f)
{
- __skb_frag_ref(&skb_shinfo(skb)->frags[f]);
+ __skb_frag_ref(&skb_shinfo(skb)->frags[f], skb->pp_recycle);
}
int skb_pp_cow_data(struct page_pool *pool, struct sk_buff **pskb,
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 1f918e602bc4..6d234faa9d9e 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1006,6 +1006,21 @@ int skb_cow_data_for_xdp(struct page_pool *pool, struct sk_buff **pskb,
EXPORT_SYMBOL(skb_cow_data_for_xdp);
#if IS_ENABLED(CONFIG_PAGE_POOL)
+bool napi_pp_get_page(struct page *page)
+{
+
+ struct page *head_page;
+
+ head_page = compound_head(page);
+
+ if (!is_pp_page(page))
+ return false;
+
+ page_pool_ref_page(head_page);
+ return true;
+}
+EXPORT_SYMBOL(napi_pp_get_page);
+
bool napi_pp_put_page(struct page *page, bool napi_safe)
{
bool allow_direct = false;
@@ -1058,37 +1073,6 @@ static bool skb_pp_recycle(struct sk_buff *skb, void *data, bool napi_safe)
return napi_pp_put_page(virt_to_page(data), napi_safe);
}
-/**
- * skb_pp_frag_ref() - Increase fragment references of a page pool aware skb
- * @skb: page pool aware skb
- *
- * Increase the fragment reference count (pp_ref_count) of a skb. This is
- * intended to gain fragment references only for page pool aware skbs,
- * i.e. when skb->pp_recycle is true, and not for fragments in a
- * non-pp-recycling skb. It has a fallback to increase references on normal
- * pages, as page pool aware skbs may also have normal page fragments.
- */
-static int skb_pp_frag_ref(struct sk_buff *skb)
-{
- struct skb_shared_info *shinfo;
- struct page *head_page;
- int i;
-
- if (!skb->pp_recycle)
- return -EINVAL;
-
- shinfo = skb_shinfo(skb);
-
- for (i = 0; i < shinfo->nr_frags; i++) {
- head_page = compound_head(skb_frag_page(&shinfo->frags[i]));
- if (likely(is_pp_page(head_page)))
- page_pool_ref_page(head_page);
- else
- page_ref_inc(head_page);
- }
- return 0;
-}
-
static void skb_kfree_head(void *head, unsigned int end_offset)
{
if (end_offset == SKB_SMALL_HEAD_HEADROOM)
@@ -4199,7 +4183,7 @@ int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen)
to++;
} else {
- __skb_frag_ref(fragfrom);
+ __skb_frag_ref(fragfrom, skb->pp_recycle);
skb_frag_page_copy(fragto, fragfrom);
skb_frag_off_copy(fragto, fragfrom);
skb_frag_size_set(fragto, todo);
@@ -4849,7 +4833,7 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb,
}
*nskb_frag = (i < 0) ? skb_head_frag_to_page_desc(frag_skb) : *frag;
- __skb_frag_ref(nskb_frag);
+ __skb_frag_ref(nskb_frag, nskb->pp_recycle);
size = skb_frag_size(nskb_frag);
if (pos < offset) {
@@ -5980,10 +5964,8 @@ bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
/* if the skb is not cloned this does nothing
* since we set nr_frags to 0.
*/
- if (skb_pp_frag_ref(from)) {
- for (i = 0; i < from_shinfo->nr_frags; i++)
- __skb_frag_ref(&from_shinfo->frags[i]);
- }
+ for (i = 0; i < from_shinfo->nr_frags; i++)
+ __skb_frag_ref(&from_shinfo->frags[i], from->pp_recycle);
to->truesize += delta;
to->len += len;
--
2.44.0.278.ge034bb2e1d-goog
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