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authorMenglong Dong <dong.menglong@zte.com.cn>2021-06-27 23:37:44 -0700
committerDavid S. Miller <davem@davemloft.net>2021-06-28 13:31:57 -0700
commit0c6de0c943dbb42831bf7502eb5c007f71e752d2 (patch)
tree6364734be857c1e028de3cd2e6f7a1a37721f18c /net/tipc/bcast.c
parent1b077ce1c5be7cdb0e40ea2c2565ed8c878b05e9 (diff)
downloadlinux-0c6de0c943dbb42831bf7502eb5c007f71e752d2.tar.gz
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>
Diffstat (limited to 'net/tipc/bcast.c')
-rw-r--r--net/tipc/bcast.c2
1 files changed, 1 insertions, 1 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,