From: Menglong Dong dong.menglong@zte.com.cn
[ Upstream commit 0c6de0c943dbb42831bf7502eb5c007f71e752d2 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- 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 d0fc5fadbc68..b7943da9d095 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 {