Date: Wed, 14 Jul 2004 00:30:40 -0400 (EDT) From: Robert Watson <rwatson@FreeBSD.org> To: current@FreeBSD.org Subject: Some netgraph node global locking patches Message-ID: <Pine.NEB.3.96L.1040714002717.83353E-100000@fledge.watson.org>
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I'm starting to work my way through locking for the various netgraph nodes
shipped with FreeBSD, but have a problem in that I can't easily configure
and test all of them. As such, I've done some initial global variable
locking, and am working on tricking various FreeBSD developers into
locking down per-node/per-instance variables, etc.
The attached patch locks down global variables found in the following node
implementations:
//depot/vendor/freebsd/src/sys/netgraph/ng_eiface.c
//depot/vendor/freebsd/src/sys/netgraph/ng_fec.c
//depot/vendor/freebsd/src/sys/netgraph/ng_iface.c
//depot/vendor/freebsd/src/sys/netgraph/ng_ppp.c
//depot/vendor/freebsd/src/sys/netgraph/ng_tty.c
If people using these netgraph modules could give the patch a spin, that
would be good. There are a couple of comments regarding locking nits.
If you're the owner of a netgraph module and want to take a lock at
locking down the softc/per-instance variables, I'd appreciate any help I
can get, as there's quite a bit of other locking work for the stack left
in the queue.
Robert N M Watson FreeBSD Core Team, TrustedBSD Projects
robert@fledge.watson.org Principal Research Scientist, McAfee Research
--- //depot/vendor/freebsd/src/sys/netgraph/ng_eiface.c 2004/07/04 16:15:35
+++ //depot/user/rwatson/netperf/sys/netgraph/ng_eiface.c 2004/07/09 21:19:53
@@ -33,8 +33,10 @@
#include <sys/systm.h>
#include <sys/errno.h>
#include <sys/kernel.h>
+#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
+#include <sys/mutex.h>
#include <sys/errno.h>
#include <sys/sockio.h>
#include <sys/socket.h>
@@ -119,6 +121,8 @@
#define UNITS_BITSPERWORD (sizeof(*ng_eiface_units) * NBBY)
+static struct mtx ng_eiface_mtx;
+MTX_SYSINIT(ng_eiface, &ng_eiface_mtx, "ng_eiface", MTX_DEF);
/************************************************************************
HELPER STUFF
@@ -132,6 +136,7 @@
{
int index, bit;
+ mtx_lock(&ng_eiface_mtx);
for (index = 0; index < ng_eiface_units_len
&& ng_eiface_units[index] == 0; index++);
if (index == ng_eiface_units_len) { /* extend array */
@@ -140,8 +145,10 @@
newlen = (2 * ng_eiface_units_len) + 4;
MALLOC(newarray, int *, newlen * sizeof(*ng_eiface_units),
M_NETGRAPH, M_NOWAIT);
- if (newarray == NULL)
+ if (newarray == NULL) {
+ mtx_unlock(&ng_eiface_mtx);
return (ENOMEM);
+ }
bcopy(ng_eiface_units, newarray,
ng_eiface_units_len * sizeof(*ng_eiface_units));
for (i = ng_eiface_units_len; i < newlen; i++)
@@ -157,6 +164,7 @@
ng_eiface_units[index] &= ~(1 << bit);
*unit = (index * UNITS_BITSPERWORD) + bit;
ng_units_in_use++;
+ mtx_unlock(&ng_eiface_mtx);
return (0);
}
@@ -170,6 +178,7 @@
index = unit / UNITS_BITSPERWORD;
bit = unit % UNITS_BITSPERWORD;
+ mtx_lock(&ng_eiface_mtx);
KASSERT(index < ng_eiface_units_len,
("%s: unit=%d len=%d", __func__, unit, ng_eiface_units_len));
KASSERT((ng_eiface_units[index] & (1 << bit)) == 0,
@@ -187,6 +196,7 @@
ng_eiface_units_len = 0;
ng_eiface_units = NULL;
}
+ mtx_unlock(&ng_eiface_mtx);
}
/************************************************************************
--- //depot/vendor/freebsd/src/sys/netgraph/ng_fec.c 2004/07/04 16:15:35
+++ //depot/user/rwatson/netperf/sys/netgraph/ng_fec.c 2004/07/09 21:19:53
@@ -257,6 +257,9 @@
#define UNITS_BITSPERWORD (sizeof(*ng_fec_units) * NBBY)
+static struct mtx ng_fec_mtx;
+MTX_SYSINIT(ng_fec, &ng_fec_mtx, "ng_fec", MTX_DEF);
+
/*
* Find the first free unit number for a new interface.
* Increase the size of the unit bitmap as necessary.
@@ -266,6 +269,7 @@
{
int index, bit;
+ mtx_lock(&ng_fec_mtx);
for (index = 0; index < ng_fec_units_len
&& ng_fec_units[index] == 0; index++);
if (index == ng_fec_units_len) { /* extend array */
@@ -274,8 +278,10 @@
newlen = (2 * ng_fec_units_len) + 4;
MALLOC(newarray, int *, newlen * sizeof(*ng_fec_units),
M_NETGRAPH, M_NOWAIT);
- if (newarray == NULL)
+ if (newarray == NULL) {
+ mtx_unlock(&ng_fec_mtx);
return (ENOMEM);
+ }
bcopy(ng_fec_units, newarray,
ng_fec_units_len * sizeof(*ng_fec_units));
for (i = ng_fec_units_len; i < newlen; i++)
@@ -291,6 +297,7 @@
ng_fec_units[index] &= ~(1 << bit);
*unit = (index * UNITS_BITSPERWORD) + bit;
ng_units_in_use++;
+ mtx_unlock(&ng_fec_mtx);
return (0);
}
@@ -304,6 +311,7 @@
index = unit / UNITS_BITSPERWORD;
bit = unit % UNITS_BITSPERWORD;
+ mtx_lock(&ng_fec_mtx);
KASSERT(index < ng_fec_units_len,
("%s: unit=%d len=%d", __FUNCTION__, unit, ng_fec_units_len));
KASSERT((ng_fec_units[index] & (1 << bit)) == 0,
@@ -321,6 +329,7 @@
ng_fec_units_len = 0;
ng_fec_units = NULL;
}
+ mtx_unlock(&ng_fec_mtx);
}
/************************************************************************
--- //depot/vendor/freebsd/src/sys/netgraph/ng_iface.c 2004/07/04 16:15:35
+++ //depot/user/rwatson/netperf/sys/netgraph/ng_iface.c 2004/07/09 21:19:53
@@ -59,8 +59,10 @@
#include <sys/systm.h>
#include <sys/errno.h>
#include <sys/kernel.h>
+#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
+#include <sys/mutex.h>
#include <sys/errno.h>
#include <sys/random.h>
#include <sys/sockio.h>
@@ -218,6 +220,9 @@
#define UNITS_BITSPERWORD (sizeof(*ng_iface_units) * NBBY)
+static struct mtx ng_iface_mtx;
+MTX_SYSINIT(ng_iface, &ng_iface_mtx, "ng_iface", MTX_DEF);
+
/************************************************************************
HELPER STUFF
************************************************************************/
@@ -289,6 +294,7 @@
{
int index, bit;
+ mtx_lock(&ng_iface_mtx);
for (index = 0; index < ng_iface_units_len
&& ng_iface_units[index] == 0; index++);
if (index == ng_iface_units_len) { /* extend array */
@@ -297,8 +303,10 @@
newlen = (2 * ng_iface_units_len) + 4;
MALLOC(newarray, int *, newlen * sizeof(*ng_iface_units),
M_NETGRAPH_IFACE, M_NOWAIT);
- if (newarray == NULL)
+ if (newarray == NULL) {
+ mtx_unlock(&ng_iface_mtx);
return (ENOMEM);
+ }
bcopy(ng_iface_units, newarray,
ng_iface_units_len * sizeof(*ng_iface_units));
for (i = ng_iface_units_len; i < newlen; i++)
@@ -314,6 +322,7 @@
ng_iface_units[index] &= ~(1 << bit);
*unit = (index * UNITS_BITSPERWORD) + bit;
ng_units_in_use++;
+ mtx_unlock(&ng_iface_mtx);
return (0);
}
@@ -327,6 +336,7 @@
index = unit / UNITS_BITSPERWORD;
bit = unit % UNITS_BITSPERWORD;
+ mtx_lock(&ng_iface_mtx);
KASSERT(index < ng_iface_units_len,
("%s: unit=%d len=%d", __func__, unit, ng_iface_units_len));
KASSERT((ng_iface_units[index] & (1 << bit)) == 0,
@@ -344,6 +354,7 @@
ng_iface_units_len = 0;
ng_iface_units = NULL;
}
+ mtx_unlock(&ng_iface_mtx);
}
/************************************************************************
--- //depot/vendor/freebsd/src/sys/netgraph/ng_ppp.c 2004/06/26 22:25:30
+++ //depot/user/rwatson/netperf/sys/netgraph/ng_ppp.c 2004/06/27 16:41:59
@@ -362,6 +362,13 @@
static int *compareLatencies; /* hack for ng_ppp_intcmp() */
+/*
+ * XXXRW: An ugly synchronization hack to protect an ugly hack.
+ */
+static struct mtx ng_ppp_latencies_mtx;
+MTX_SYSINIT(ng_ppp_latencies, &ng_ppp_latencies_mtx, "ng_ppp_latencies",
+ MTX_DEF);
+
/* Address and control field header */
static const u_char ng_ppp_acf[2] = { 0xff, 0x03 };
@@ -1764,10 +1771,12 @@
}
/* Sort active links by latency */
+ mtx_lock(&ng_ppp_latencies_mtx);
compareLatencies = latency;
qsort(sortByLatency,
priv->numActiveLinks, sizeof(*sortByLatency), ng_ppp_intcmp);
compareLatencies = NULL;
+ mtx_unlock(&ng_ppp_latencies_mtx);
/* Find the interval we need (add links in sortByLatency[] order) */
for (numFragments = 1;
@@ -1858,6 +1867,8 @@
const int index1 = *((const int *) v1);
const int index2 = *((const int *) v2);
+ mtx_assert(&ng_ppp_latencies_mtx, MA_OWNED);
+
return compareLatencies[index1] - compareLatencies[index2];
}
--- //depot/vendor/freebsd/src/sys/netgraph/ng_pppoe.c 2004/06/26 22:25:30
+++ //depot/user/rwatson/netperf/sys/netgraph/ng_pppoe.c 2004/06/27 16:41:59
@@ -238,6 +238,10 @@
};
typedef struct PPPOE *priv_p;
+/*
+ * XXXRW: Leave this unsynchronized, since only a single field is modified,
+ * and it's done so infrequently. Likewise, pppoe_mode.
+ */
struct ether_header eh_prototype =
{{0xff,0xff,0xff,0xff,0xff,0xff},
{0x00,0x00,0x00,0x00,0x00,0x00},
--- //depot/vendor/freebsd/src/sys/netgraph/ng_tty.c 2004/06/26 08:45:27
+++ //depot/user/rwatson/netperf/sys/netgraph/ng_tty.c 2004/06/27 03:09:51
@@ -166,10 +166,18 @@
};
NETGRAPH_INIT(tty, &typestruct);
+/*
+ * XXXRW: ngt_unit is protected by ng_tty_mtx. ngt_ldisc is constant once
+ * ng_tty is initialized. ngt_nodeop_ok is untouched, and might want to be a
+ * sleep lock in the future?
+ */
static int ngt_unit;
static int ngt_nodeop_ok; /* OK to create/remove node */
static int ngt_ldisc;
+static struct mtx ng_tty_mtx;
+MTX_SYSINIT(ng_tty, &ng_tty_mtx, "ng_tty", MTX_DEF);
+
/******************************************************************
LINE DISCIPLINE METHODS
******************************************************************/
@@ -214,7 +222,9 @@
FREE(sc, M_NETGRAPH);
goto done;
}
+ mtx_lock(&ng_tty_mtx);
snprintf(name, sizeof(name), "%s%d", typestruct.name, ngt_unit++);
+ mtx_unlock(&ng_tty_mtx);
/* Assign node its name */
if ((error = ng_name_node(sc->node, name))) {
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