net: move skb ref helpers to new header

Add a new header, linux/skbuff_ref.h, which contains all the skb_*_ref()
helpers. Many of the consumers of skbuff.h do not actually use any of
the skb ref helpers, and we can speed up compilation a bit by minimizing
this header file.

Additionally in the later patch in the series we add page_pool support
to skb_frag_ref(), which requires some page_pool dependencies. We can
now add these dependencies to skbuff_ref.h instead of a very ubiquitous
skbuff.h

Signed-off-by: Mina Almasry <almasrymina@google.com>
Link: https://lore.kernel.org/r/20240410190505.1225848-2-almasrymina@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 75 insertions, 0 deletions

diff --git a/include/linux/skbuff_ref.h b/include/linux/skbuff_ref.h
new file mode 100644
index 000000000000..11f0a4063403
--- /dev/null
+++ b/include/linux/skbuff_ref.h
@@ -0,0 +1,75 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ *	Skb ref helpers.
+ *
+ */
+
+#ifndef _LINUX_SKBUFF_REF_H
+#define _LINUX_SKBUFF_REF_H
+
+#include <linux/skbuff.h>
+
+/**
+ * __skb_frag_ref - take an addition reference on a paged fragment.
+ * @frag: the paged fragment
+ *
+ * Takes an additional reference on the paged fragment @frag.
+ */
+static inline void __skb_frag_ref(skb_frag_t *frag)
+{
+	get_page(skb_frag_page(frag));
+}
+
+/**
+ * skb_frag_ref - take an addition reference on a paged fragment of an skb.
+ * @skb: the buffer
+ * @f: the fragment offset.
+ *
+ * Takes an additional reference on the @f'th paged fragment of @skb.
+ */
+static inline void skb_frag_ref(struct sk_buff *skb, int f)
+{
+	__skb_frag_ref(&skb_shinfo(skb)->frags[f]);
+}
+
+bool napi_pp_put_page(struct page *page);
+
+static inline void
+skb_page_unref(struct page *page, bool recycle)
+{
+#ifdef CONFIG_PAGE_POOL
+	if (recycle && napi_pp_put_page(page))
+		return;
+#endif
+	put_page(page);
+}
+
+/**
+ * __skb_frag_unref - release a reference on a paged fragment.
+ * @frag: the paged fragment
+ * @recycle: recycle the page if allocated via page_pool
+ *
+ * Releases a reference on the paged fragment @frag
+ * or recycles the page via the page_pool API.
+ */
+static inline void __skb_frag_unref(skb_frag_t *frag, bool recycle)
+{
+	skb_page_unref(skb_frag_page(frag), recycle);
+}
+
+/**
+ * skb_frag_unref - release a reference on a paged fragment of an skb.
+ * @skb: the buffer
+ * @f: the fragment offset
+ *
+ * Releases a reference on the @f'th paged fragment of @skb.
+ */
+static inline void skb_frag_unref(struct sk_buff *skb, int f)
+{
+	struct skb_shared_info *shinfo = skb_shinfo(skb);
+
+	if (!skb_zcopy_managed(skb))
+		__skb_frag_unref(&shinfo->frags[f], skb->pp_recycle);
+}
+
+#endif	/* _LINUX_SKBUFF_REF_H */