netdev - [PATCH v3 23/26] net: Add support for netmem in skb

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Message-Id: <20230111042214.907030-24-willy@infradead.org>
Date:   Wed, 11 Jan 2023 04:22:11 +0000
From:   "Matthew Wilcox (Oracle)" <willy@...radead.org>
To:     Jesper Dangaard Brouer <hawk@...nel.org>,
        Ilias Apalodimas <ilias.apalodimas@...aro.org>
Cc:     "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        netdev@...r.kernel.org, linux-mm@...ck.org,
        Shakeel Butt <shakeelb@...gle.com>,
        Jesse Brandeburg <jesse.brandeburg@...el.com>
Subject: [PATCH v3 23/26] net: Add support for netmem in skb_frag

Allow drivers to add netmem to skbs & retrieve them again.  If the
VM_BUG_ON triggers, we can add a call to compound_head() either in
this function or in page_netmem().

Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
Reviewed-by: Jesse Brandeburg <jesse.brandeburg@...el.com>
---
 include/linux/skbuff.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 4c8492401a10..4b04240385cc 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -3346,6 +3346,12 @@ static inline struct page *skb_frag_page(const skb_frag_t *frag)
 	return frag->bv_page;
 }
 
+static inline struct netmem *skb_frag_netmem(const skb_frag_t *frag)
+{
+	VM_BUG_ON_PAGE(PageTail(frag->bv_page), frag->bv_page);
+	return page_netmem(frag->bv_page);
+}
+
 /**
  * __skb_frag_ref - take an addition reference on a paged fragment.
  * @frag: the paged fragment
@@ -3454,6 +3460,11 @@ static inline void __skb_frag_set_page(skb_frag_t *frag, struct page *page)
 	frag->bv_page = page;
 }
 
+static inline void __skb_frag_set_netmem(skb_frag_t *frag, struct netmem *nmem)
+{
+	__skb_frag_set_page(frag, netmem_page(nmem));
+}
+
 /**
  * skb_frag_set_page - sets the page contained in a paged fragment of an skb
  * @skb: the buffer
-- 
2.35.1