First in a series of changes to remove the now-unused Giant compatibility

framework for non-MPSAFE network protocols:

- Remove debug_mpsafenet variable, sysctl, and tunable.
- Remove NET_NEEDS_GIANT() and associate SYSINITSs used by it to force
  debug.mpsafenet=0 if non-MPSAFE protocols are compiled into the kernel.
- Remove logic to automatically flag interrupt handlers as non-MPSAFE if
  debug.mpsafenet is set for an INTR_TYPE_NET handler.
- Remove logic to automatically flag netisr handlers as non-MPSAFE if
  debug.mpsafenet is set.
- Remove references in a few subsystems, including NFS and Cronyx drivers,
  which keyed off debug_mpsafenet to determine various aspects of their own
  locking behavior.
- Convert NET_LOCK_GIANT(), NET_UNLOCK_GIANT(), and NET_ASSERT_GIANT into
  no-op's, as their entire behavior was determined by the value in
  debug_mpsafenet.
- Alias NET_CALLOUT_MPSAFE to CALLOUT_MPSAFE.

Many remaining references to NET_.*_GIANT() and NET_CALLOUT_MPSAFE are still
present in subsystems, and will be removed in followup commits.

Reviewed by:	bz, jhb
Approved by:	re (kensmith)

sys/dev/ath/ath_rate/amrr/amrr.c

@@ -504,7 +504,7 @@ ath_rate_attach(struct ath_softc *sc)
 	if (asc == NULL)
 		return NULL;
 	asc->arc.arc_space = sizeof(struct amrr_node);
-	callout_init(&asc->timer, debug_mpsafenet ? CALLOUT_MPSAFE : 0);
+	callout_init(&asc->timer, CALLOUT_MPSAFE);
 	ath_rate_sysctlattach(sc);
 
 	return &asc->arc;

sys/dev/ath/ath_rate/onoe/onoe.c

@@ -478,7 +478,7 @@ ath_rate_attach(struct ath_softc *sc)
 	if (osc == NULL)
 		return NULL;
 	osc->arc.arc_space = sizeof(struct onoe_node);
-	callout_init(&osc->timer, debug_mpsafenet ? CALLOUT_MPSAFE : 0);
+	callout_init(&osc->timer, CALLOUT_MPSAFE);
 	ath_rate_sysctlattach(sc);
 
 	return &osc->arc;

sys/dev/ce/if_ce.c

@@ -2604,13 +2604,6 @@ static int ce_modevent (module_t mod, int type, void *unused)
 #if __FreeBSD_version < 500000
 	dev = makedev (CDEV_MAJOR, 0);
 #endif
-#if __FreeBSD_version >= 501114
-	if (!debug_mpsafenet && ce_mpsafenet) {
-		printf ("WORNING! Network stack is not MPSAFE. "
-			"Turning off debug.ce.mpsafenet.\n");
-		ce_mpsafenet = 0;
-	}
-#endif
 #if __FreeBSD_version >= 502103
 	if (ce_mpsafenet)
 		ce_cdevsw.d_flags &= ~D_NEEDGIANT;

sys/dev/cp/if_cp.c

@@ -2265,11 +2265,6 @@ static int cp_modevent (module_t mod, int type, void *unused)
 {
 	static int load_count = 0;
 
-	if (!debug_mpsafenet && cp_mpsafenet) {
-		printf ("WORNING! Network stack is not MPSAFE. "
-			"Turning off debug.cp.mpsafenet.\n");
-		cp_mpsafenet = 0;
-	}
 	if (cp_mpsafenet)
 		cp_cdevsw.d_flags &= ~D_NEEDGIANT;
 

sys/dev/ctau/if_ct.c

@@ -2206,11 +2206,6 @@ static int ct_modevent (module_t mod, int type, void *unused)
 {
 	static int load_count = 0;
 
-	if (!debug_mpsafenet && ct_mpsafenet) {
-		printf ("WORNING! Network stack is not MPSAFE. "
-			"Turning off debug.ct.mpsafenet.\n");
-		ct_mpsafenet = 0;
-	}
 	if (ct_mpsafenet)
 		ct_cdevsw.d_flags &= ~D_NEEDGIANT;
 

sys/dev/cx/if_cx.c

@@ -2523,11 +2523,6 @@ static int cx_modevent (module_t mod, int type, void *unused)
 {
 	static int load_count = 0;
 
-	if (!debug_mpsafenet && cx_mpsafenet) {
-		printf ("WORNING! Network stack is not MPSAFE. "
-			"Turning off debug.cx.mpsafenet.\n");
-		cx_mpsafenet = 0;
-	}
 	if (cx_mpsafenet)
 		cx_cdevsw.d_flags &= ~D_NEEDGIANT;
 

sys/kern/subr_bus.c

@@ -3464,9 +3464,6 @@ bus_setup_intr(device_t dev, struct resource *r, int flags,
 	int error;
 
 	if (dev->parent != NULL) {
-		if ((flags &~ INTR_ENTROPY) == (INTR_TYPE_NET | INTR_MPSAFE) &&
-		    !debug_mpsafenet)
-			flags &= ~INTR_MPSAFE;
 		error = BUS_SETUP_INTR(dev->parent, dev, r, flags,
 		    filter, handler, arg, cookiep);
 		if (error == 0) {

sys/kern/uipc_domain.c

@@ -211,13 +211,8 @@ domaininit(void *dummy)
 	if (max_linkhdr < 16)		/* XXX */
 		max_linkhdr = 16;
 
-	if (debug_mpsafenet) {
-		callout_init(&pffast_callout, CALLOUT_MPSAFE);
-		callout_init(&pfslow_callout, CALLOUT_MPSAFE);
-	} else {
-		callout_init(&pffast_callout, 0);
-		callout_init(&pfslow_callout, 0);
-	}
+	callout_init(&pffast_callout, CALLOUT_MPSAFE);
+	callout_init(&pfslow_callout, CALLOUT_MPSAFE);
 
 	mtx_lock(&dom_mtx);
 	KASSERT(domain_init_status == 0, ("domaininit called too late!"));

sys/net/if.c

@@ -2694,9 +2694,7 @@ void
 if_start(struct ifnet *ifp)
 {
 
-	NET_ASSERT_GIANT();
-
-	if ((ifp->if_flags & IFF_NEEDSGIANT) != 0 && debug_mpsafenet != 0) {
+	if (ifp->if_flags & IFF_NEEDSGIANT) {
 		if (mtx_owned(&Giant))
 			(*(ifp)->if_start)(ifp);
 		else
@@ -2711,11 +2709,6 @@ if_start_deferred(void *context, int pending)
 {
 	struct ifnet *ifp;
 
-	/*
-	 * This code must be entered with Giant, and should never run if
-	 * we're not running with debug.mpsafenet.
-	 */
-	KASSERT(debug_mpsafenet != 0, ("if_start_deferred: debug.mpsafenet"));
 	GIANT_REQUIRED;
 
 	ifp = context;

sys/net/if_ethersubr.c

@@ -922,7 +922,7 @@ ether_ifattach(struct ifnet *ifp, const u_int8_t *lla)
 			break; 
 	if (i != ifp->if_addrlen)
 		if_printf(ifp, "Ethernet address: %6D\n", lla, ":");
-	if (debug_mpsafenet && (ifp->if_flags & IFF_NEEDSGIANT) != 0)
+	if (ifp->if_flags & IFF_NEEDSGIANT)
 		if_printf(ifp, "if_start running deferred for Giant\n");
 }
 

sys/net/netisr.c

@@ -56,24 +56,6 @@
 #include <net/if_var.h>
 #include <net/netisr.h>
 
-/* 
- * debug_mpsafenet controls network subsystem-wide use of the Giant lock,
- * from system calls down to interrupt handlers.  It can be changed only via
- * a tunable at boot, not at run-time, due to the complexity of unwinding.
- * The compiled default is set via a kernel option; right now, the default
- * unless otherwise specified is to run the network stack without Giant.
- */
-#ifdef NET_WITH_GIANT
-int	debug_mpsafenet = 0;
-#else
-int	debug_mpsafenet = 1;
-#endif
-int	debug_mpsafenet_toolatetotwiddle = 0;
-
-TUNABLE_INT("debug.mpsafenet", &debug_mpsafenet);
-SYSCTL_INT(_debug, OID_AUTO, mpsafenet, CTLFLAG_RD, &debug_mpsafenet, 0,
-    "Enable/disable MPSAFE network support");
-
 volatile unsigned int	netisr;	/* scheduling bits for network */
 
 struct netisr {
@@ -84,78 +66,6 @@ struct netisr {
 
 static void *net_ih;
 
-/*
- * Not all network code is currently capable of running MPSAFE; however,
- * most of it is.  Since those sections that are not are generally optional
- * components not shipped with default kernels, we provide a basic way to
- * determine whether MPSAFE operation is permitted: based on a default of
- * yes, we permit non-MPSAFE components to use a registration call to
- * identify that they require Giant.  If the system is early in the boot
- * process still, then we change the debug_mpsafenet setting to choose a
- * non-MPSAFE execution mode (degraded).  If it's too late for that (since
- * the setting cannot be changed at run time), we generate a console warning
- * that the configuration may be unsafe.
- */
-static int mpsafe_warn_count;
-
-/*
- * Function call implementing registration of a non-MPSAFE network component.
- */
-void
-net_warn_not_mpsafe(const char *component)
-{
-
-	/*
-	 * If we're running with Giant over the network stack, there is no
-	 * problem.
-	 */
-	if (!debug_mpsafenet)
-		return;
-
-	/*
-	 * If it's not too late to change the MPSAFE setting for the network
-	 * stack, do so now.  This effectively suppresses warnings by
-	 * components registering later.
-	 */
-	if (!debug_mpsafenet_toolatetotwiddle) {
-		debug_mpsafenet = 0;
-		printf("WARNING: debug.mpsafenet forced to 0 as %s requires "
-		    "Giant\n", component);
-		return;
-	}
-
-	/*
-	 * We must run without Giant, so generate a console warning with some
-	 * information with what to do about it.  The system may be operating
-	 * unsafely, however.
-	 */
-	printf("WARNING: Network stack Giant-free, but %s requires Giant.\n",
-	    component);
-	if (mpsafe_warn_count == 0)
-		printf("    Consider adding 'options NET_WITH_GIANT' or "
-		    "setting debug.mpsafenet=0\n");
-	mpsafe_warn_count++;
-}
-
-/*
- * This sysinit is run after any pre-loaded or compiled-in components have
- * announced that they require Giant, but before any modules loaded at
- * run-time.
- */
-static void
-net_mpsafe_toolate(void *arg)
-{
-
-	debug_mpsafenet_toolatetotwiddle = 1;
-
-	if (!debug_mpsafenet)
-		printf("WARNING: MPSAFE network stack disabled, expect "
-		    "reduced performance.\n");
-}
-
-SYSINIT(net_mpsafe_toolate, SI_SUB_SETTINGS, SI_ORDER_ANY, net_mpsafe_toolate,
-    NULL);
-
 void
 legacy_setsoftnet(void)
 {
@@ -170,8 +80,6 @@ netisr_register(int num, netisr_t *handler, struct ifqueue *inq, int flags)
 	    ("bad isr %d", num));
 	netisrs[num].ni_handler = handler;
 	netisrs[num].ni_queue = inq;
-	if ((flags & NETISR_MPSAFE) && !debug_mpsafenet)
-		flags &= ~NETISR_MPSAFE;
 	netisrs[num].ni_flags = flags;
 }
 

sys/nfsserver/nfs_srvsubs.c

@@ -549,10 +549,7 @@ nfsrv_modevent(module_t mod, int type, void *data)
 		nfsrv_initcache();	/* Init the server request cache */
 		NFSD_LOCK();
 		nfsrv_init(0);		/* Init server data structures */
-		if (debug_mpsafenet)
-			callout_init(&nfsrv_callout, CALLOUT_MPSAFE);
-		else
-			callout_init(&nfsrv_callout, 0);
+		callout_init(&nfsrv_callout, CALLOUT_MPSAFE);
 		NFSD_UNLOCK();
 		nfsrv_timer(0);
 

sys/nfsserver/nfs_syscalls.c

@@ -561,16 +561,10 @@ nfssvc_nfsd(struct thread *td)
 			nfsd->nfsd_slp = NULL;
 			nfsrv_slpderef(slp);
 		}
-		KASSERT(!(debug_mpsafenet == 0 && !mtx_owned(&Giant)),
-		    ("nfssvc_nfsd(): debug.mpsafenet=0 && !Giant"));
-		KASSERT(!(debug_mpsafenet == 1 && mtx_owned(&Giant)),
-		    ("nfssvc_nfsd(): debug.mpsafenet=1 && Giant"));
+		mtx_assert(&Giant, MA_NOTOWNED);
 	}
 done:
-	KASSERT(!(debug_mpsafenet == 0 && !mtx_owned(&Giant)),
-	    ("nfssvc_nfsd(): debug.mpsafenet=0 && !Giant"));
-	KASSERT(!(debug_mpsafenet == 1 && mtx_owned(&Giant)),
-	    ("nfssvc_nfsd(): debug.mpsafenet=1 && Giant"));
+	mtx_assert(&Giant, MA_NOTOWNED);
 	TAILQ_REMOVE(&nfsd_head, nfsd, nfsd_chain);
 	splx(s);
 	free((caddr_t)nfsd, M_NFSD);

sys/sys/kernel.h

@@ -343,11 +343,6 @@ struct tunable_str {
 #define	TUNABLE_STR_FETCH(path, var, size)			\
 	getenv_string((path), (var), (size))
 
-void	net_warn_not_mpsafe(const char *component);
-#define	NET_NEEDS_GIANT(component)					\
-	SYSINIT(__CONCAT(__net_warn_not_mpsafe_, __LINE__),		\
-	    SI_SUB_SETTINGS, SI_ORDER_SECOND, net_warn_not_mpsafe, component);
-
 struct intr_config_hook {
 	TAILQ_ENTRY(intr_config_hook) ich_links;
 	void	(*ich_func)(void *arg);

sys/sys/mutex.h

@@ -397,35 +397,18 @@ do {									\
 } while (0)
 
 /*
- * Network MPSAFE temporary workarounds.  When debug_mpsafenet
- * is 1 the network is assumed to operate without Giant on the
- * input path and protocols that require Giant must collect it
- * on entry.  When 0 Giant is grabbed in the network interface
- * ISR's and in the netisr path and there is no need to grab
- * the Giant lock.  Note that, unlike PICKUP_GIANT() and
- * DROP_GIANT(), these macros directly wrap mutex operations
- * without special recursion handling.
- *
- * This mechanism is intended as temporary until everything of
- * importance is properly locked.  Note: the semantics for
- * NET_{LOCK,UNLOCK}_GIANT() are not the same as DROP_GIANT()
- * and PICKUP_GIANT(), as they are plain mutex operations
- * without a recursion counter.
+ * With the advent of fine-grained locking, the Giant lock is no longer
+ * required around the network stack.  These macros exist for historical
+ * reasons, allowing conditional acquisition of Giant based on a debugging
+ * setting, and will be removed.
  */
-extern	int debug_mpsafenet;		/* defined in net/netisr.c */
 #define	NET_LOCK_GIANT() do {						\
-	if (!debug_mpsafenet)						\
-		mtx_lock(&Giant);					\
 } while (0)
 #define	NET_UNLOCK_GIANT() do {						\
-	if (!debug_mpsafenet)						\
-		mtx_unlock(&Giant);					\
 } while (0)
 #define	NET_ASSERT_GIANT() do {						\
-	if (!debug_mpsafenet)						\
-		mtx_assert(&Giant, MA_OWNED);				\
 } while (0)
-#define	NET_CALLOUT_MPSAFE	(debug_mpsafenet ? CALLOUT_MPSAFE : 0)
+#define	NET_CALLOUT_MPSAFE	CALLOUT_MPSAFE
 
 struct mtx_args {
 	struct mtx	*ma_mtx;