[PATCH v6 net-next 0/2] net: tipc: fix FB_MTU eat two pages and do some code cleanup

[PATCH v6 net-next 0/2] net: tipc: fix FB_MTU eat two pages and do some code cleanup

[menglong8.dong]

From: Menglong Dong <dong.menglong@zte.com.cn>

In the first patch, FB_MTU is redefined to make sure data size will not
exceed PAGE_SIZE. Besides, I removed the alignment for buf_size in
tipc_buf_acquire, because skb_alloc_fclone will do the alignment job.

In the second patch, I removed align() in msg.c and replace it with
ALIGN().

Changes since V5:
- remove blank line after Fixes in commit log in the first patch

Changes since V4:
- remove ONE_PAGE_SKB_SZ and replace it with one_page_mtu in the first
  patch.
- fix some code style problems for the second patch.


Menglong Dong (2):
  net: tipc: fix FB_MTU eat two pages
  net: tipc: replace align() with ALIGN in msg.c

 net/tipc/bcast.c |  2 +-
 net/tipc/msg.c   | 27 +++++++++++----------------
 net/tipc/msg.h   |  3 ++-
 3 files changed, 14 insertions(+), 18 deletions(-)

-- 
2.25.1

[PATCH v6 net-next 1/2] net: tipc: fix FB_MTU eat two pages

[menglong8.dong]

From: Menglong Dong <dong.menglong@zte.com.cn>

FB_MTU is used in 'tipc_msg_build()' to alloc smaller skb when memory
allocation fails, which can avoid unnecessary sending failures.

The value of FB_MTU now is 3744, and the data size will be:

  (3744 + SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) + \
    SKB_DATA_ALIGN(BUF_HEADROOM + BUF_TAILROOM + 3))

which is larger than one page(4096), and two pages will be allocated.

To avoid it, replace '3744' with a calculation:

  (PAGE_SIZE - SKB_DATA_ALIGN(BUF_OVERHEAD) - \
    SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))

What's more, alloc_skb_fclone() will call SKB_DATA_ALIGN for data size,
and it's not necessary to make alignment for buf_size in
tipc_buf_acquire(). So, just remove it.

Fixes: 4c94cc2d3d57 ("tipc: fall back to smaller MTU if allocation of local send skb fails")
Signed-off-by: Menglong Dong <dong.menglong@zte.com.cn>
Acked-by: Jon Maloy <jmaloy@redhat.com>
---
V6:
- remove blank line after Fixes in commit log

V5:
- remove ONE_PAGE_SKB_SZ and replace it with one_page_mtu

V4:
- fallback to V2

V3:
- split tipc_msg_build to tipc_msg_build and tipc_msg_frag
- introduce tipc_buf_acquire_flex, which is able to alloc skb for
  local message
- add the variate 'local' in tipc_msg_build to check if this is a
  local message.

V2:
- define FB_MTU in msg.c instead of introduce a new file
- remove align for buf_size in tipc_buf_acquire()
---
 net/tipc/bcast.c |  2 +-
 net/tipc/msg.c   | 17 ++++++++---------
 net/tipc/msg.h   |  3 ++-
 3 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/net/tipc/bcast.c b/net/tipc/bcast.c
index d4beca895992..593846d25214 100644
--- a/net/tipc/bcast.c
+++ b/net/tipc/bcast.c
@@ -699,7 +699,7 @@ int tipc_bcast_init(struct net *net)
 	spin_lock_init(&tipc_net(net)->bclock);
 
 	if (!tipc_link_bc_create(net, 0, 0, NULL,
-				 FB_MTU,
+				 one_page_mtu,
 				 BCLINK_WIN_DEFAULT,
 				 BCLINK_WIN_DEFAULT,
 				 0,
diff --git a/net/tipc/msg.c b/net/tipc/msg.c
index ce6ab54822d8..7053c22e393e 100644
--- a/net/tipc/msg.c
+++ b/net/tipc/msg.c
@@ -44,12 +44,15 @@
 #define MAX_FORWARD_SIZE 1024
 #ifdef CONFIG_TIPC_CRYPTO
 #define BUF_HEADROOM ALIGN(((LL_MAX_HEADER + 48) + EHDR_MAX_SIZE), 16)
-#define BUF_TAILROOM (TIPC_AES_GCM_TAG_SIZE)
+#define BUF_OVERHEAD (BUF_HEADROOM + TIPC_AES_GCM_TAG_SIZE)
 #else
 #define BUF_HEADROOM (LL_MAX_HEADER + 48)
-#define BUF_TAILROOM 16
+#define BUF_OVERHEAD BUF_HEADROOM
 #endif
 
+const int one_page_mtu = PAGE_SIZE - SKB_DATA_ALIGN(BUF_OVERHEAD) -
+			 SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
+
 static unsigned int align(unsigned int i)
 {
 	return (i + 3) & ~3u;
@@ -69,13 +72,8 @@ static unsigned int align(unsigned int i)
 struct sk_buff *tipc_buf_acquire(u32 size, gfp_t gfp)
 {
 	struct sk_buff *skb;
-#ifdef CONFIG_TIPC_CRYPTO
-	unsigned int buf_size = (BUF_HEADROOM + size + BUF_TAILROOM + 3) & ~3u;
-#else
-	unsigned int buf_size = (BUF_HEADROOM + size + 3) & ~3u;
-#endif
 
-	skb = alloc_skb_fclone(buf_size, gfp);
+	skb = alloc_skb_fclone(BUF_OVERHEAD + size, gfp);
 	if (skb) {
 		skb_reserve(skb, BUF_HEADROOM);
 		skb_put(skb, size);
@@ -395,7 +393,8 @@ int tipc_msg_build(struct tipc_msg *mhdr, struct msghdr *m, int offset,
 		if (unlikely(!skb)) {
 			if (pktmax != MAX_MSG_SIZE)
 				return -ENOMEM;
-			rc = tipc_msg_build(mhdr, m, offset, dsz, FB_MTU, list);
+			rc = tipc_msg_build(mhdr, m, offset, dsz,
+					    one_page_mtu, list);
 			if (rc != dsz)
 				return rc;
 			if (tipc_msg_assemble(list))
diff --git a/net/tipc/msg.h b/net/tipc/msg.h
index 5d64596ba987..64ae4c4c44f8 100644
--- a/net/tipc/msg.h
+++ b/net/tipc/msg.h
@@ -99,9 +99,10 @@ struct plist;
 #define MAX_H_SIZE                60	/* Largest possible TIPC header size */
 
 #define MAX_MSG_SIZE (MAX_H_SIZE + TIPC_MAX_USER_MSG_SIZE)
-#define FB_MTU                  3744
 #define TIPC_MEDIA_INFO_OFFSET	5
 
+extern const int one_page_mtu;
+
 struct tipc_skb_cb {
 	union {
 		struct {
-- 
2.25.1

[PATCH v6 net-next 2/2] net: tipc: replace align() with ALIGN in msg.c

[menglong8.dong]

From: Menglong Dong <dong.menglong@zte.com.cn>

The function align() which is defined in msg.c is redundant, replace it
with ALIGN() and introduce a BUF_ALIGN().

Signed-off-by: Menglong Dong <dong.menglong@zte.com.cn>
Acked-by: Jon Maloy <jmaloy@redhat.com>
---
 net/tipc/msg.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/net/tipc/msg.c b/net/tipc/msg.c
index 7053c22e393e..5c9fd4791c4b 100644
--- a/net/tipc/msg.c
+++ b/net/tipc/msg.c
@@ -41,6 +41,7 @@
 #include "name_table.h"
 #include "crypto.h"
 
+#define BUF_ALIGN(x) ALIGN(x, 4)
 #define MAX_FORWARD_SIZE 1024
 #ifdef CONFIG_TIPC_CRYPTO
 #define BUF_HEADROOM ALIGN(((LL_MAX_HEADER + 48) + EHDR_MAX_SIZE), 16)
@@ -53,11 +54,6 @@
 const int one_page_mtu = PAGE_SIZE - SKB_DATA_ALIGN(BUF_OVERHEAD) -
 			 SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 
-static unsigned int align(unsigned int i)
-{
-	return (i + 3) & ~3u;
-}
-
 /**
  * tipc_buf_acquire - creates a TIPC message buffer
  * @size: message size (including TIPC header)
@@ -489,7 +485,7 @@ static bool tipc_msg_bundle(struct sk_buff *bskb, struct tipc_msg *msg,
 
 	msz = msg_size(msg);
 	bsz = msg_size(bmsg);
-	offset = align(bsz);
+	offset = BUF_ALIGN(bsz);
 	pad = offset - bsz;
 
 	if (unlikely(skb_tailroom(bskb) < (pad + msz)))
@@ -546,7 +542,7 @@ bool tipc_msg_try_bundle(struct sk_buff *tskb, struct sk_buff **skb, u32 mss,
 
 	/* Make a new bundle of the two messages if possible */
 	tsz = msg_size(buf_msg(tskb));
-	if (unlikely(mss < align(INT_H_SIZE + tsz) + msg_size(msg)))
+	if (unlikely(mss < BUF_ALIGN(INT_H_SIZE + tsz) + msg_size(msg)))
 		return true;
 	if (unlikely(pskb_expand_head(tskb, INT_H_SIZE, mss - tsz - INT_H_SIZE,
 				      GFP_ATOMIC)))
@@ -605,7 +601,7 @@ bool tipc_msg_extract(struct sk_buff *skb, struct sk_buff **iskb, int *pos)
 	if (unlikely(!tipc_msg_validate(iskb)))
 		goto none;
 
-	*pos += align(imsz);
+	*pos += BUF_ALIGN(imsz);
 	return true;
 none:
 	kfree_skb(skb);
-- 
2.32.0

Re: [PATCH v6 net-next 0/2] net: tipc: fix FB_MTU eat two pages and do some code cleanup

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (refs/heads/master):

On Sun, 27 Jun 2021 23:37:43 -0700 you wrote:
> From: Menglong Dong <dong.menglong@zte.com.cn>
> 
> In the first patch, FB_MTU is redefined to make sure data size will not
> exceed PAGE_SIZE. Besides, I removed the alignment for buf_size in
> tipc_buf_acquire, because skb_alloc_fclone will do the alignment job.
> 
> In the second patch, I removed align() in msg.c and replace it with
> ALIGN().
> 
> [...]

Here is the summary with links:
  - [v6,net-next,1/2] net: tipc: fix FB_MTU eat two pages
    https://git.kernel.org/netdev/net-next/c/0c6de0c943db
  - [v6,net-next,2/2] net: tipc: replace align() with ALIGN in msg.c
    https://git.kernel.org/netdev/net-next/c/d4cfb7fe5713

You are awesome, thank you!
--
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