in Xserver/os/connection.c, the Xserver calls CheckConnections() to check
the validity of the client file descriptors.  Even though the select is
called with a timeout of zero, it is still possible for the the OS to return
EINTR.  When this happens, an active client connection is dropped from the
server.

The LogWrite() is what I used to prove this is happening.  It can be removed.

N.B.: this patch includes the patch made for bug #7876.

--- xc/programs/Xserver/os/connection.c	2004-04-23 14:54:28.000000000 -0500
+++ xc/programs/Xserver/os/connection.c	2006-12-04 13:09:39.565957120 -0600
@@ -1056,8 +1056,11 @@ CheckConnections(void)
             FD_ZERO(&tmask);
             FD_SET(curclient, &tmask);
             r = Select (curclient + 1, &tmask, NULL, NULL, &notime);
-            if (r < 0)
-		CloseDownClient(clients[ConnectionTranslation[curclient]]);
+	    if (r < 0 && GetConnectionTranslation(curclient) > 0)
+		LogWrite(1, "CheckConnections: close down client, errno %d\n", errno);
+		if ((EINTR != errno) && (EAGAIN != errno))
+		    CloseDownClient(clients[ConnectionTranslation[curclient]]);
+	    }
 	    mask &= ~((fd_mask)1 << curoff);
 	}
     }