net: tipc: fix FB_MTU eat two pages
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>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/tipc/msg.c b/net/tipc/msg.c
index ce6ab54..7053c22 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))