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Message-ID: <20230810015751.3297321-8-almasrymina@google.com>
Date: Wed, 9 Aug 2023 18:57:43 -0700
From: Mina Almasry <almasrymina@...gle.com>
To: netdev@...r.kernel.org, linux-media@...r.kernel.org,
dri-devel@...ts.freedesktop.org
Cc: Mina Almasry <almasrymina@...gle.com>, "David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
Jesper Dangaard Brouer <hawk@...nel.org>, Ilias Apalodimas <ilias.apalodimas@...aro.org>,
Arnd Bergmann <arnd@...db.de>, David Ahern <dsahern@...nel.org>,
Willem de Bruijn <willemdebruijn.kernel@...il.com>, Sumit Semwal <sumit.semwal@...aro.org>,
"Christian König" <christian.koenig@....com>, Jason Gunthorpe <jgg@...pe.ca>,
Hari Ramakrishnan <rharix@...gle.com>, Dan Williams <dan.j.williams@...el.com>,
Andy Lutomirski <luto@...nel.org>, stephen@...workplumber.org, sdf@...gle.com
Subject: [RFC PATCH v2 07/11] net: support non paged skb frags
Make skb_frag_page() fail in the case where the frag is not backed
by a page, and fix its relevent callers to handle this case.
Correctly handle skb_frag refcounting in the page_pool_iovs case.
Signed-off-by: Mina Almasry <almasrymina@...gle.com>
---
include/linux/skbuff.h | 40 +++++++++++++++++++++++++++++++++-------
net/core/gro.c | 2 +-
net/core/skbuff.c | 3 +++
net/ipv4/tcp.c | 10 +++++++++-
4 files changed, 46 insertions(+), 9 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index faaba050f843..5520587050c4 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -3389,15 +3389,38 @@ static inline void skb_frag_off_copy(skb_frag_t *fragto,
fragto->bv_offset = fragfrom->bv_offset;
}
+/* Returns true if the skb_frag contains a page_pool_iov. */
+static inline bool skb_frag_is_page_pool_iov(const skb_frag_t *frag)
+{
+ return page_is_page_pool_iov(frag->bv_page);
+}
+
/**
* skb_frag_page - retrieve the page referred to by a paged fragment
* @frag: the paged fragment
*
- * Returns the &struct page associated with @frag.
+ * Returns the &struct page associated with @frag. Returns NULL if this frag
+ * has no associated page.
*/
static inline struct page *skb_frag_page(const skb_frag_t *frag)
{
- return frag->bv_page;
+ if (!page_is_page_pool_iov(frag->bv_page))
+ return frag->bv_page;
+
+ return NULL;
+}
+
+/**
+ * skb_frag_page_pool_iov - retrieve the page_pool_iov referred to by fragment
+ * @frag: the fragment
+ *
+ * Returns the &struct page_pool_iov associated with @frag. Returns NULL if this
+ * frag has no associated page_pool_iov.
+ */
+static inline struct page_pool_iov *
+skb_frag_page_pool_iov(const skb_frag_t *frag)
+{
+ return page_to_page_pool_iov(frag->bv_page);
}
/**
@@ -3408,7 +3431,7 @@ static inline struct page *skb_frag_page(const skb_frag_t *frag)
*/
static inline void __skb_frag_ref(skb_frag_t *frag)
{
- get_page(skb_frag_page(frag));
+ page_pool_page_get_many(frag->bv_page, 1);
}
/**
@@ -3426,13 +3449,13 @@ static inline void skb_frag_ref(struct sk_buff *skb, int f)
static inline void
napi_frag_unref(skb_frag_t *frag, bool recycle, bool napi_safe)
{
- struct page *page = skb_frag_page(frag);
-
#ifdef CONFIG_PAGE_POOL
- if (recycle && page_pool_return_skb_page(page, napi_safe))
+ if (recycle && page_pool_return_skb_page(frag->bv_page, napi_safe))
return;
+ page_pool_page_put_many(frag->bv_page, 1);
+#else
+ put_page(skb_frag_page(frag));
#endif
- put_page(page);
}
/**
@@ -3472,6 +3495,9 @@ static inline void skb_frag_unref(struct sk_buff *skb, int f)
*/
static inline void *skb_frag_address(const skb_frag_t *frag)
{
+ if (!skb_frag_page(frag))
+ return NULL;
+
return page_address(skb_frag_page(frag)) + skb_frag_off(frag);
}
diff --git a/net/core/gro.c b/net/core/gro.c
index 0759277dc14e..42d7f6755f32 100644
--- a/net/core/gro.c
+++ b/net/core/gro.c
@@ -376,7 +376,7 @@ static inline void skb_gro_reset_offset(struct sk_buff *skb, u32 nhoff)
NAPI_GRO_CB(skb)->frag0 = NULL;
NAPI_GRO_CB(skb)->frag0_len = 0;
- if (!skb_headlen(skb) && pinfo->nr_frags &&
+ if (!skb_headlen(skb) && pinfo->nr_frags && skb_frag_page(frag0) &&
!PageHighMem(skb_frag_page(frag0)) &&
(!NET_IP_ALIGN || !((skb_frag_off(frag0) + nhoff) & 3))) {
NAPI_GRO_CB(skb)->frag0 = skb_frag_address(frag0);
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index a298992060e6..ac79881a2630 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2939,6 +2939,9 @@ static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
for (seg = 0; seg < skb_shinfo(skb)->nr_frags; seg++) {
const skb_frag_t *f = &skb_shinfo(skb)->frags[seg];
+ if (WARN_ON_ONCE(!skb_frag_page(f)))
+ return false;
+
if (__splice_segment(skb_frag_page(f),
skb_frag_off(f), skb_frag_size(f),
offset, len, spd, false, sk, pipe))
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 88f4ebab12ac..7893df0e22ee 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2160,6 +2160,9 @@ static int tcp_zerocopy_receive(struct sock *sk,
break;
}
page = skb_frag_page(frags);
+ if (WARN_ON_ONCE(!page))
+ break;
+
prefetchw(page);
pages[pages_to_map++] = page;
length += PAGE_SIZE;
@@ -4415,7 +4418,12 @@ int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *hp,
for (i = 0; i < shi->nr_frags; ++i) {
const skb_frag_t *f = &shi->frags[i];
unsigned int offset = skb_frag_off(f);
- struct page *page = skb_frag_page(f) + (offset >> PAGE_SHIFT);
+ struct page *page = skb_frag_page(f);
+
+ if (WARN_ON_ONCE(!page))
+ return 1;
+
+ page += offset >> PAGE_SHIFT;
sg_set_page(&sg, page, skb_frag_size(f),
offset_in_page(offset));
--
2.41.0.640.ga95def55d0-goog
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