[PATCH net-next v3 0/6] net: Remove unused function parameters in skbuff.c

[PATCH net-next v3 0/6] net: Remove unused function parameters in skbuff.c

[Michal Luczaj]

Couple of cleanup patches to get rid of unused function parameters around
skbuff.c, plus little things spotted along the way.

Offshoot of my question in [1], but way more contained. Found by adding
"-Wunused-parameter -Wno-error" to KBUILD_CFLAGS and grepping for specific
skbuff.c warnings.

[1]: https://lore.kernel.org/netdev/972af569-0c90-4585-9e1f-f2266dab6ec6@rbox.co/

Signed-off-by: Michal Luczaj <mhal@rbox.co>
---
Changes in v3:
- Keep skb_splice_bits() @flags [Jakub, Paolo]
- Link to v2: https://lore.kernel.org/r/20250626-splice-drop-unused-v2-0-3268fac1af89@rbox.co

Changes in v2:
- Fix typos in commit messages
- Remove one more unused parameter in skbuff.c (patch 9)
- Collect R-b, add a one-line cleanup of smc_rx_splice() (patch 7) [Simon]
- Link to v1: https://lore.kernel.org/r/20250624-splice-drop-unused-v1-0-cf641a676d04@rbox.co

---
Michal Luczaj (6):
      net: splice: Drop unused @pipe
      net: splice: Drop unused @gfp
      net: splice: Drop nr_pages_max initialization
      net/smc: Drop nr_pages_max initialization
      net: skbuff: Drop unused @skb
      net: skbuff: Drop unused @skb

 .../chelsio/inline_crypto/chtls/chtls_io.c         |  3 +-
 include/linux/skbuff.h                             |  2 +-
 net/core/skbuff.c                                  | 34 +++++++++-------------
 net/ipv4/ip_output.c                               |  3 +-
 net/ipv4/tcp.c                                     |  3 +-
 net/ipv6/ip6_output.c                              |  3 +-
 net/kcm/kcmsock.c                                  |  3 +-
 net/smc/smc_rx.c                                   |  1 -
 net/unix/af_unix.c                                 |  3 +-
 9 files changed, 20 insertions(+), 35 deletions(-)
---
base-commit: e96ee511c906c59b7c4e6efd9d9b33917730e000
change-id: 20250618-splice-drop-unused-0e4ea8a12681

Best regards,
-- 
Michal Luczaj <mhal@rbox.co>

[PATCH net-next v3 1/6] net: splice: Drop unused @pipe

[Michal Luczaj]

Since commit 41c73a0d44c9 ("net: speedup skb_splice_bits()"),
__splice_segment() and spd_fill_page() do not use the @pipe argument. Drop
it.

While adapting the callers, move one line to enforce reverse xmas tree
order.

No functional change intended.

Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Michal Luczaj <mhal@rbox.co>
---
 net/core/skbuff.c | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index d6420b74ea9c6a9c53a7c16634cce82a1cd1bbd3..ae0f1aae3c91d914020c64e0703732b9c6cd8511 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3060,10 +3060,8 @@ static bool spd_can_coalesce(const struct splice_pipe_desc *spd,
 /*
  * Fill page/offset/length into spd, if it can hold more pages.
  */
-static bool spd_fill_page(struct splice_pipe_desc *spd,
-			  struct pipe_inode_info *pipe, struct page *page,
-			  unsigned int *len, unsigned int offset,
-			  bool linear,
+static bool spd_fill_page(struct splice_pipe_desc *spd, struct page *page,
+			  unsigned int *len, unsigned int offset, bool linear,
 			  struct sock *sk)
 {
 	if (unlikely(spd->nr_pages == MAX_SKB_FRAGS))
@@ -3091,8 +3089,7 @@ static bool __splice_segment(struct page *page, unsigned int poff,
 			     unsigned int plen, unsigned int *off,
 			     unsigned int *len,
 			     struct splice_pipe_desc *spd, bool linear,
-			     struct sock *sk,
-			     struct pipe_inode_info *pipe)
+			     struct sock *sk)
 {
 	if (!*len)
 		return true;
@@ -3111,8 +3108,7 @@ static bool __splice_segment(struct page *page, unsigned int poff,
 	do {
 		unsigned int flen = min(*len, plen);
 
-		if (spd_fill_page(spd, pipe, page, &flen, poff,
-				  linear, sk))
+		if (spd_fill_page(spd, page, &flen, poff, linear, sk))
 			return true;
 		poff += flen;
 		plen -= flen;
@@ -3130,8 +3126,8 @@ static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
 			      unsigned int *offset, unsigned int *len,
 			      struct splice_pipe_desc *spd, struct sock *sk)
 {
-	int seg;
 	struct sk_buff *iter;
+	int seg;
 
 	/* map the linear part :
 	 * If skb->head_frag is set, this 'linear' part is backed by a
@@ -3143,7 +3139,7 @@ static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
 			     skb_headlen(skb),
 			     offset, len, spd,
 			     skb_head_is_locked(skb),
-			     sk, pipe))
+			     sk))
 		return true;
 
 	/*
@@ -3160,7 +3156,7 @@ static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
 
 		if (__splice_segment(skb_frag_page(f),
 				     skb_frag_off(f), skb_frag_size(f),
-				     offset, len, spd, false, sk, pipe))
+				     offset, len, spd, false, sk))
 			return true;
 	}
 

-- 
2.49.0

[PATCH net-next v3 2/6] net: splice: Drop unused @gfp

[Michal Luczaj]

Since its introduction in commit 2e910b95329c ("net: Add a function to
splice pages into an skbuff for MSG_SPLICE_PAGES"), skb_splice_from_iter()
never used the @gfp argument. Remove it and adapt callers.

No functional change intended.

Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Michal Luczaj <mhal@rbox.co>
---
 drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_io.c | 3 +--
 include/linux/skbuff.h                                      | 2 +-
 net/core/skbuff.c                                           | 3 +--
 net/ipv4/ip_output.c                                        | 3 +--
 net/ipv4/tcp.c                                              | 3 +--
 net/ipv6/ip6_output.c                                       | 3 +--
 net/kcm/kcmsock.c                                           | 3 +--
 net/unix/af_unix.c                                          | 3 +--
 8 files changed, 8 insertions(+), 15 deletions(-)

diff --git a/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_io.c b/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_io.c
index d567e42e176011d42b9549d0cc6292a06126d61d..465fa807796439b90c949f54e203a798f06acf1f 100644
--- a/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_io.c
+++ b/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_io.c
@@ -1096,8 +1096,7 @@ int chtls_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
 			copy = size;
 
 		if (msg->msg_flags & MSG_SPLICE_PAGES) {
-			err = skb_splice_from_iter(skb, &msg->msg_iter, copy,
-						   sk->sk_allocation);
+			err = skb_splice_from_iter(skb, &msg->msg_iter, copy);
 			if (err < 0) {
 				if (err == -EMSGSIZE)
 					goto new_buf;
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 4f6dcb37bae8ada524a1e8f8de44c259cfac695b..b8b06e71b73ea3fb5210239f585f4ba714395fd7 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -5265,7 +5265,7 @@ static inline void skb_mark_for_recycle(struct sk_buff *skb)
 }
 
 ssize_t skb_splice_from_iter(struct sk_buff *skb, struct iov_iter *iter,
-			     ssize_t maxsize, gfp_t gfp);
+			     ssize_t maxsize);
 
 #endif	/* __KERNEL__ */
 #endif	/* _LINUX_SKBUFF_H */
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index ae0f1aae3c91d914020c64e0703732b9c6cd8511..a34fe37cf7a508c8380e35522d9cde266aa440f9 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -7230,7 +7230,6 @@ static void skb_splice_csum_page(struct sk_buff *skb, struct page *page,
  * @skb: The buffer to add pages to
  * @iter: Iterator representing the pages to be added
  * @maxsize: Maximum amount of pages to be added
- * @gfp: Allocation flags
  *
  * This is a common helper function for supporting MSG_SPLICE_PAGES.  It
  * extracts pages from an iterator and adds them to the socket buffer if
@@ -7241,7 +7240,7 @@ static void skb_splice_csum_page(struct sk_buff *skb, struct page *page,
  * insufficient space in the buffer to transfer anything.
  */
 ssize_t skb_splice_from_iter(struct sk_buff *skb, struct iov_iter *iter,
-			     ssize_t maxsize, gfp_t gfp)
+			     ssize_t maxsize)
 {
 	size_t frag_limit = READ_ONCE(net_hotdata.sysctl_max_skb_frags);
 	struct page *pages[8], **ppages = pages;
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index a2705d454fd645b442b2901833afa51b26512512..5d75d60efcf361ed9c3b34eaa982f6c667c716f6 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1222,8 +1222,7 @@ static int __ip_append_data(struct sock *sk,
 			if (WARN_ON_ONCE(copy > msg->msg_iter.count))
 				goto error;
 
-			err = skb_splice_from_iter(skb, &msg->msg_iter, copy,
-						   sk->sk_allocation);
+			err = skb_splice_from_iter(skb, &msg->msg_iter, copy);
 			if (err < 0)
 				goto error;
 			copy = err;
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 8a3c99246d2ed32ba45849b56830bf128e265763..039fffd7a594409a3a08546503c8c3d91a79b455 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1297,8 +1297,7 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
 			if (!copy)
 				goto wait_for_space;
 
-			err = skb_splice_from_iter(skb, &msg->msg_iter, copy,
-						   sk->sk_allocation);
+			err = skb_splice_from_iter(skb, &msg->msg_iter, copy);
 			if (err < 0) {
 				if (err == -EMSGSIZE) {
 					tcp_mark_push(tp, skb);
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 7bd29a9ff0db8d74c79f50afa5c693231e0f82d5..618ed7d72b28f43ab6d7a02e5f8f53a4d22de87a 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1760,8 +1760,7 @@ static int __ip6_append_data(struct sock *sk,
 			if (WARN_ON_ONCE(copy > msg->msg_iter.count))
 				goto error;
 
-			err = skb_splice_from_iter(skb, &msg->msg_iter, copy,
-						   sk->sk_allocation);
+			err = skb_splice_from_iter(skb, &msg->msg_iter, copy);
 			if (err < 0)
 				goto error;
 			copy = err;
diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c
index 24aec295a51cf737912f1aefe81556bd9f23331e..a0be3896a9340c2a9120bb2692e9deec84d138c6 100644
--- a/net/kcm/kcmsock.c
+++ b/net/kcm/kcmsock.c
@@ -835,8 +835,7 @@ static int kcm_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
 			if (!sk_wmem_schedule(sk, copy))
 				goto wait_for_memory;
 
-			err = skb_splice_from_iter(skb, &msg->msg_iter, copy,
-						   sk->sk_allocation);
+			err = skb_splice_from_iter(skb, &msg->msg_iter, copy);
 			if (err < 0) {
 				if (err == -EMSGSIZE)
 					goto wait_for_memory;
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 564c970d97fffe9fd264e0d02c5670026314ac57..cd0d582bc7d48fbf9cd917c72e1fe4e88232916e 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -2388,8 +2388,7 @@ static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg,
 
 		if (unlikely(msg->msg_flags & MSG_SPLICE_PAGES)) {
 			skb->ip_summed = CHECKSUM_UNNECESSARY;
-			err = skb_splice_from_iter(skb, &msg->msg_iter, size,
-						   sk->sk_allocation);
+			err = skb_splice_from_iter(skb, &msg->msg_iter, size);
 			if (err < 0)
 				goto out_free;
 

-- 
2.49.0

[PATCH net-next v3 3/6] net: splice: Drop nr_pages_max initialization

[Michal Luczaj]

splice_pipe_desc::nr_pages_max was initialized unnecessarily in commit
41c73a0d44c9 ("net: speedup skb_splice_bits()"). spd_fill_page() compares
spd->nr_pages against a constant MAX_SKB_FRAGS, which makes setting
nr_pages_max redundant.

Remove the assignment. No functional change intended.

Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Michal Luczaj <mhal@rbox.co>
---
 net/core/skbuff.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index a34fe37cf7a508c8380e35522d9cde266aa440f9..3041f7a3560d58270dffdf923825758f274c8511 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3189,7 +3189,6 @@ int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset,
 	struct splice_pipe_desc spd = {
 		.pages = pages,
 		.partial = partial,
-		.nr_pages_max = MAX_SKB_FRAGS,
 		.ops = &nosteal_pipe_buf_ops,
 		.spd_release = sock_spd_release,
 	};

-- 
2.49.0

[PATCH net-next v3 4/6] net/smc: Drop nr_pages_max initialization

[Michal Luczaj]

splice_pipe_desc::nr_pages_max was initialized unnecessarily in
commit b8d199451c99 ("net/smc: Allow virtually contiguous sndbufs or RMBs
for SMC-R"). Struct's field is unused in this context.

Remove the assignment. No functional change intended.

Suggested-by: Simon Horman <horms@kernel.org>
Reviewed-by: Sidraya Jayagond <sidraya@linux.ibm.com>
Reviewed-by: Dust Li <dust.li@linux.alibaba.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Michal Luczaj <mhal@rbox.co>
---
 net/smc/smc_rx.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/net/smc/smc_rx.c b/net/smc/smc_rx.c
index e7f1134453ef40dd81a9574d6df4ead95acd8ae5..bbba5d4dc7eb0dbb31a9800023b0caab33e87842 100644
--- a/net/smc/smc_rx.c
+++ b/net/smc/smc_rx.c
@@ -202,7 +202,6 @@ static int smc_rx_splice(struct pipe_inode_info *pipe, char *src, size_t len,
 			offset = 0;
 		}
 	}
-	spd.nr_pages_max = nr_pages;
 	spd.nr_pages = nr_pages;
 	spd.pages = pages;
 	spd.partial = partial;

-- 
2.49.0

[PATCH net-next v3 5/6] net: skbuff: Drop unused @skb

[Michal Luczaj]

Since its introduction in commit ce098da1497c ("skbuff: Introduce
slab_build_skb()"), __slab_build_skb() never used the @skb argument. Remove
it and adapt both callers.

No functional change intended.

Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Michal Luczaj <mhal@rbox.co>
---
 net/core/skbuff.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 3041f7a3560d58270dffdf923825758f274c8511..4893350bc80a105e0a2870f0de03a687c1117217 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -384,8 +384,7 @@ static inline void __finalize_skb_around(struct sk_buff *skb, void *data,
 	skb_set_kcov_handle(skb, kcov_common_handle());
 }
 
-static inline void *__slab_build_skb(struct sk_buff *skb, void *data,
-				     unsigned int *size)
+static inline void *__slab_build_skb(void *data, unsigned int *size)
 {
 	void *resized;
 
@@ -418,7 +417,7 @@ struct sk_buff *slab_build_skb(void *data)
 		return NULL;
 
 	memset(skb, 0, offsetof(struct sk_buff, tail));
-	data = __slab_build_skb(skb, data, &size);
+	data = __slab_build_skb(data, &size);
 	__finalize_skb_around(skb, data, size);
 
 	return skb;
@@ -435,7 +434,7 @@ static void __build_skb_around(struct sk_buff *skb, void *data,
 	 * using slab buffer should use slab_build_skb() instead.
 	 */
 	if (WARN_ONCE(size == 0, "Use slab_build_skb() instead"))
-		data = __slab_build_skb(skb, data, &size);
+		data = __slab_build_skb(data, &size);
 
 	__finalize_skb_around(skb, data, size);
 }

-- 
2.49.0

[PATCH net-next v3 6/6] net: skbuff: Drop unused @skb

[Michal Luczaj]

Since its introduction in commit 6fa01ccd8830 ("skbuff: Add pskb_extract()
helper function"), pskb_carve_frag_list() never used the argument @skb.
Drop it and adapt the only caller.

No functional change intended.

Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Michal Luczaj <mhal@rbox.co>
---
 net/core/skbuff.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 4893350bc80a105e0a2870f0de03a687c1117217..277f7d0666691bd54d6e005c84a2166175455490 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -6757,8 +6757,7 @@ static int pskb_carve(struct sk_buff *skb, const u32 off, gfp_t gfp);
 /* carve out the first eat bytes from skb's frag_list. May recurse into
  * pskb_carve()
  */
-static int pskb_carve_frag_list(struct sk_buff *skb,
-				struct skb_shared_info *shinfo, int eat,
+static int pskb_carve_frag_list(struct skb_shared_info *shinfo, int eat,
 				gfp_t gfp_mask)
 {
 	struct sk_buff *list = shinfo->frag_list;
@@ -6863,7 +6862,7 @@ static int pskb_carve_inside_nonlinear(struct sk_buff *skb, const u32 off,
 		skb_clone_fraglist(skb);
 
 	/* split line is in frag list */
-	if (k == 0 && pskb_carve_frag_list(skb, shinfo, off - pos, gfp_mask)) {
+	if (k == 0 && pskb_carve_frag_list(shinfo, off - pos, gfp_mask)) {
 		/* skb_frag_unref() is not needed here as shinfo->nr_frags = 0. */
 		if (skb_has_frag_list(skb))
 			kfree_skb_list(skb_shinfo(skb)->frag_list);

-- 
2.49.0

Re: [PATCH net-next v3 0/6] net: Remove unused function parameters in skbuff.c

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Wed, 02 Jul 2025 15:38:06 +0200 you wrote:
> Couple of cleanup patches to get rid of unused function parameters around
> skbuff.c, plus little things spotted along the way.
> 
> Offshoot of my question in [1], but way more contained. Found by adding
> "-Wunused-parameter -Wno-error" to KBUILD_CFLAGS and grepping for specific
> skbuff.c warnings.
> 
> [...]

Here is the summary with links:
  - [net-next,v3,1/6] net: splice: Drop unused @pipe
    https://git.kernel.org/netdev/net-next/c/1024f1207161
  - [net-next,v3,2/6] net: splice: Drop unused @gfp
    https://git.kernel.org/netdev/net-next/c/25489a4f5564
  - [net-next,v3,3/6] net: splice: Drop nr_pages_max initialization
    (no matching commit)
  - [net-next,v3,4/6] net/smc: Drop nr_pages_max initialization
    (no matching commit)
  - [net-next,v3,5/6] net: skbuff: Drop unused @skb
    https://git.kernel.org/netdev/net-next/c/ad0ac6cd9c04
  - [net-next,v3,6/6] net: skbuff: Drop unused @skb
    https://git.kernel.org/netdev/net-next/c/ab34e14258cd

You are awesome, thank you!
-- 
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