Commit 77b75f4d authored by Rainer Weikusat's avatar Rainer Weikusat Committed by David S. Miller

unix: use wq_has_sleeper in unix_dgram_recvmsg

The current unix_dgram_recvmsg does a wake up for every received
datagram. This seems wasteful as only SOCK_DGRAM client sockets in an
n:1 association with a server socket will ever wait because of the
associated condition. The patch below changes the function such that the
wake up only happens if wq_has_sleeper indicates that someone actually
wants to be notified. Testing with SOCK_SEQPACKET and SOCK_DGRAM socket
seems to confirm that this is an improvment.
Signed-Off-By: default avatarRainer Weikusat <rweikusat@mobileactivedefense.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 75c4a57c
...@@ -1914,8 +1914,10 @@ static int unix_dgram_recvmsg(struct socket *sock, struct msghdr *msg, ...@@ -1914,8 +1914,10 @@ static int unix_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
goto out_unlock; goto out_unlock;
} }
wake_up_interruptible_sync_poll(&u->peer_wait, if (wq_has_sleeper(&u->peer_wait))
POLLOUT | POLLWRNORM | POLLWRBAND); wake_up_interruptible_sync_poll(&u->peer_wait,
POLLOUT | POLLWRNORM |
POLLWRBAND);
if (msg->msg_name) if (msg->msg_name)
unix_copy_addr(msg, skb->sk); unix_copy_addr(msg, skb->sk);
......
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