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Index: lib/libc/sys/listen.2
===================================================================
--- lib/libc/sys/listen.2
+++ lib/libc/sys/listen.2
@@ -28,7 +28,7 @@
.\" From: @(#)listen.2 8.2 (Berkeley) 12/11/93
.\" $FreeBSD$
.\"
-.Dd August 18, 2016
+.Dd April 13, 2020
.Dt LISTEN 2
.Os
.Sh NAME
@@ -110,6 +110,13 @@
.Fa backlog
is silently forced to
.Va kern.ipc.soacceptqueue .
+.Pp
+If the listen queue overflows, the kernel will emit a LOG_DEBUG syslog message.
+The
+.Xr sysctl 3
+MIB variable
+.Va kern.ipc.sooverinterval
+specified a per-socket limit on how often the kernel will emit these messages.
.Sh INTERACTION WITH ACCEPT FILTERS
When accept filtering is used on a socket, a second queue will
be used to hold sockets that have connected, but have not yet
Index: sys/kern/uipc_socket.c
===================================================================
--- sys/kern/uipc_socket.c
+++ sys/kern/uipc_socket.c
@@ -571,6 +571,11 @@
&regression_sonewconn_earlytest, 0, "Perform early sonewconn limit test");
#endif
+static timeval overinterval = { 60, 0 };
+SYSCTL_TIMEVAL_SEC(_kern_ipc, OID_AUTO, sooverinterval, CTLFLAG_RW,
+ &overinterval,
+ "Delay in seconds between warnings for listen socket overflows");
+
/*
* When an attempt at a new connection is noted on a socket which accepts
* connections, sonewconn is called. If the connection is possible (subject
@@ -583,34 +588,43 @@
struct socket *
sonewconn(struct socket *head, int connstatus)
{
- static struct timeval lastover;
- static struct timeval overinterval = { 60, 0 };
- static int overcount;
-
struct socket *so;
- u_int over;
+ int overcount;
+ u_int qlen;
+ bool dolog, over;
SOLISTEN_LOCK(head);
over = (head->sol_qlen > 3 * head->sol_qlimit / 2);
- SOLISTEN_UNLOCK(head);
#ifdef REGRESSION
if (regression_sonewconn_earlytest && over) {
#else
if (over) {
#endif
- overcount++;
+ head->sol_overcount++;
+ dolog = !!ratecheck(&head->sol_lastover, &overinterval);
- if (ratecheck(&lastover, &overinterval)) {
+ /*
+ * If we're going to log, copy the overflow count and queue
+ * length from the listen socket before dropping the lock.
+ * Also, reset the overflow count.
+ */
+ if (dolog) {
+ overcount = head->sol_overcount;
+ head->sol_overcount = 0;
+ qlen = head->sol_qlen;
+ }
+ SOLISTEN_UNLOCK(head);
+
+ if (dolog) {
log(LOG_DEBUG, "%s: pcb %p: Listen queue overflow: "
"%i already in queue awaiting acceptance "
"(%d occurrences)\n",
- __func__, head->so_pcb, head->sol_qlen, overcount);
-
- overcount = 0;
+ __func__, head->so_pcb, qlen, overcount);
}
return (NULL);
}
+ SOLISTEN_UNLOCK(head);
VNET_ASSERT(head->so_vnet != NULL, ("%s: so %p vnet is NULL",
__func__, head));
so = soalloc(head->so_vnet);
Index: sys/sys/socketvar.h
===================================================================
--- sys/sys/socketvar.h
+++ sys/sys/socketvar.h
@@ -172,6 +172,10 @@
short sol_sbsnd_flags;
sbintime_t sol_sbrcv_timeo;
sbintime_t sol_sbsnd_timeo;
+
+ /* Information tracking listen queue overflows. */
+ struct timeval sol_lastover; /* (e) */
+ int sol_overcount; /* (e) */
};
};
};

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