In accept1(), falloc() is called after the process has awoken, but prior

to removing the connection from the queue. The problem here is that
falloc() may block and this would allow another process to accept the
connection instead. If this happens to leave the queue empty, then the
system will panic with an "accept: nothing queued".

Also changed a wakeup() to a wakeup_one() to avoid the "thundering herd"
problem on new connections in Apache (or any other application that has
multiple processes blocked in accept() for the same socket).

1 files changed, 3 insertions, 3 deletions

diff --git a/sys/kern/uipc_socket2.c b/sys/kern/uipc_socket2.c
index e19db0c..4bddd1a 100644
--- a/sys/kern/uipc_socket2.c
+++ b/sys/kern/uipc_socket2.c
@@ -31,7 +31,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)uipc_socket2.c	8.1 (Berkeley) 6/10/93
- *	$Id: uipc_socket2.c,v 1.21 1997/02/19 19:15:43 wollman Exp $
+ *	$Id: uipc_socket2.c,v 1.22 1997/02/24 20:30:57 wollman Exp $
  */
 
 #include <sys/param.h>
@@ -111,9 +111,9 @@ soisconnected(so)
 		TAILQ_INSERT_TAIL(&head->so_comp, so, so_list);
 		so->so_state |= SS_COMP;
 		sorwakeup(head);
-		wakeup((caddr_t)&head->so_timeo);
+		wakeup_one(&head->so_timeo);
 	} else {
-		wakeup((caddr_t)&so->so_timeo);
+		wakeup(&so->so_timeo);
 		sorwakeup(so);
 		sowwakeup(so);
 	}