Export a few SMP related symbols in UP kernels as well. This is needed to

aid other kernel code, especially code which can be in a module such as
the acpi_cpu(4) driver, to work properly with both SMP and UP kernels.
The exported symbols include mp_ncpus, all_cpus, mp_maxid, smp_started, and
the smp_rendezvous() function.  This also means that CPU_ABSENT() is now
always implemented the same on all kernels.

Approved by:	re (scottl)

3 files changed, 44 insertions, 7 deletions

diff --git a/sys/conf/files b/sys/conf/files
index 8eee001..710fb63 100644
--- a/sys/conf/files
+++ b/sys/conf/files
@@ -1152,7 +1152,7 @@ kern/subr_prof.c	standard
 kern/subr_rman.c	standard
 kern/subr_sbuf.c	standard
 kern/subr_scanf.c	standard
-kern/subr_smp.c		optional smp
+kern/subr_smp.c		standard
 kern/subr_taskqueue.c	standard
 kern/subr_trap.c	standard
 kern/subr_turnstile.c	standard
diff --git a/sys/kern/subr_smp.c b/sys/kern/subr_smp.c
index b6fd97f..b3b81ac 100644
--- a/sys/kern/subr_smp.c
+++ b/sys/kern/subr_smp.c
@@ -48,10 +48,13 @@ __FBSDID("$FreeBSD$");
 
 #include <machine/smp.h>
 
+#ifdef SMP
 volatile u_int stopped_cpus;
 volatile u_int started_cpus;
 
 void (*cpustop_restartfunc)(void);
+#endif
+
 int mp_ncpus;
 
 volatile int smp_started;
@@ -73,6 +76,7 @@ int smp_cpus = 1;	/* how many cpu's running */
 SYSCTL_INT(_kern_smp, OID_AUTO, cpus, CTLFLAG_RD, &smp_cpus, 0,
     "Number of CPUs online");
 
+#ifdef SMP
 /* Enable forwarding of a signal to a process running on a different CPU */
 static int forward_signal_enabled = 1;
 SYSCTL_INT(_kern_smp, OID_AUTO, forward_signal_enabled, CTLFLAG_RW,
@@ -331,3 +335,35 @@ smp_rendezvous(void (* setup_func)(void *),
 	/* release lock */
 	mtx_unlock_spin(&smp_rv_mtx);
 }
+#else /* !SMP */
+
+/*
+ * Provide dummy SMP support for UP kernels.  Modules that need to use SMP
+ * APIs will still work using this dummy support.
+ */
+static void
+mp_setvariables_for_up(void *dummy)
+{
+	mp_ncpus = 1;
+	mp_maxid = PCPU_GET(cpuid);
+	all_cpus = PCPU_GET(cpumask);
+	KASSERT(PCPU_GET(cpuid) == 0, ("UP must have a CPU ID of zero"));
+}
+SYSINIT(cpu_mp_setvariables, SI_SUB_TUNABLES, SI_ORDER_FIRST,
+    mp_setvariables_for_up, NULL)
+
+void
+smp_rendezvous(void (* setup_func)(void *), 
+	       void (* action_func)(void *),
+	       void (* teardown_func)(void *),
+	       void *arg)
+{
+
+	if (setup_func != NULL)
+		setup_func(arg);
+	if (action_func != NULL)
+		action_func(arg);
+	if (teardown_func != NULL)
+		teardown_func(arg);
+}
+#endif /* SMP */
diff --git a/sys/sys/smp.h b/sys/sys/smp.h
index 24ef367..cd96ebe 100644
--- a/sys/sys/smp.h
+++ b/sys/sys/smp.h
@@ -45,14 +45,16 @@ struct cpu_top {
 
 extern struct cpu_top *smp_topology;
 extern void (*cpustop_restartfunc)(void);
-extern int mp_ncpus;
 extern int smp_active;
-extern volatile int smp_started;
 extern int smp_cpus;
-extern u_int all_cpus;
 extern volatile u_int started_cpus;
 extern volatile u_int stopped_cpus;
+#endif /* SMP */
+
+extern u_int all_cpus;
 extern u_int mp_maxid;
+extern int mp_ncpus;
+extern volatile int smp_started;
 
 /*
  * Macro allowing us to determine whether a CPU is absent at any given
@@ -61,6 +63,7 @@ extern u_int mp_maxid;
  */
 #define	CPU_ABSENT(x_cpu)	((all_cpus & (1 << (x_cpu))) == 0)
 
+#ifdef SMP
 /*
  * Machine dependent functions used to initialize MP support.
  *
@@ -92,13 +95,11 @@ void	forward_roundrobin(void);
 int	restart_cpus(u_int);
 int	stop_cpus(u_int);
 void	smp_rendezvous_action(void);
+#endif /* SMP */
 void	smp_rendezvous(void (*)(void *), 
 		       void (*)(void *),
 		       void (*)(void *),
 		       void *arg);
-#else /* SMP */
-#define	CPU_ABSENT(x_cpu)	(0)
-#endif /* SMP */
 #endif /* !LOCORE */
 #endif /* _KERNEL */
 #endif /* _SYS_SMP_H_ */