Add reader/writer lock around mem_range_attr_get() and mem_range_attr_set().

Compile sys/dev/mem/memutil.c for all supported platforms and remove now
unnecessary dev_mem_md_init().  Consistently define mem_range_softc from
mem.c for all platforms.  Add missing #include guards for machine/memdev.h
and sys/memrange.h.  Clean up some nearby style(9) nits.

MFC after:	1 month

2 files changed, 40 insertions, 9 deletions

diff --git a/sys/dev/mem/memdev.c b/sys/dev/mem/memdev.c
index 9fb33d2..28ed6eb 100644
--- a/sys/dev/mem/memdev.c
+++ b/sys/dev/mem/memdev.c
@@ -34,6 +34,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/kernel.h>
 #include <sys/lock.h>
 #include <sys/malloc.h>
+#include <sys/memrange.h>
 #include <sys/module.h>
 #include <sys/mutex.h>
 #include <sys/proc.h>
@@ -80,7 +81,7 @@ mem_modevent(module_t mod __unused, int type, void *data __unused)
 	case MOD_LOAD:
 		if (bootverbose)
 			printf("mem: <memory>\n");
-		dev_mem_md_init(); /* Machine dependant bit */
+		mem_range_init();
 		memdev = make_dev(&mem_cdevsw, CDEV_MINOR_MEM,
 			UID_ROOT, GID_KMEM, 0640, "mem");
 		kmemdev = make_dev(&mem_cdevsw, CDEV_MINOR_KMEM,
@@ -88,6 +89,7 @@ mem_modevent(module_t mod __unused, int type, void *data __unused)
 		break;
 
 	case MOD_UNLOAD:
+		mem_range_destroy();
 		destroy_dev(memdev);
 		destroy_dev(kmemdev);
 		break;
diff --git a/sys/dev/mem/memutil.c b/sys/dev/mem/memutil.c
index f514f50..f4ea103 100644
--- a/sys/dev/mem/memutil.c
+++ b/sys/dev/mem/memutil.c
@@ -28,35 +28,64 @@
 __FBSDID("$FreeBSD$");
 
 #include <sys/param.h>
+#include <sys/kernel.h>
+#include <sys/lock.h>
 #include <sys/malloc.h>
 #include <sys/memrange.h>
+#include <sys/rwlock.h>
 #include <sys/systm.h>
 
+static struct rwlock	mr_lock;
+
 /*
  * Implementation-neutral, kernel-callable functions for manipulating
  * memory range attributes.
  */
+void
+mem_range_init(void)
+{
+
+	if (mem_range_softc.mr_op == NULL)
+		return;
+	rw_init(&mr_lock, "memrange");
+	mem_range_softc.mr_op->init(&mem_range_softc);
+}
+
+void
+mem_range_destroy(void)
+{
+
+	if (mem_range_softc.mr_op == NULL)
+		return;
+	rw_destroy(&mr_lock);
+}
+
 int
 mem_range_attr_get(struct mem_range_desc *mrd, int *arg)
 {
-	/* can we handle this? */
+	int nd;
+
 	if (mem_range_softc.mr_op == NULL)
 		return (EOPNOTSUPP);
-
-	if (*arg == 0)
+	nd = *arg;
+	rw_rlock(&mr_lock);
+	if (nd == 0)
 		*arg = mem_range_softc.mr_ndesc;
 	else
-		bcopy(mem_range_softc.mr_desc, mrd,
-			(*arg) * sizeof(struct mem_range_desc));
+		bcopy(mem_range_softc.mr_desc, mrd, nd * sizeof(*mrd));
+	rw_runlock(&mr_lock);
 	return (0);
 }
 
 int
 mem_range_attr_set(struct mem_range_desc *mrd, int *arg)
 {
-	/* can we handle this? */
+	int ret;
+
 	if (mem_range_softc.mr_op == NULL)
 		return (EOPNOTSUPP);
-
-	return (mem_range_softc.mr_op->set(&mem_range_softc, mrd, arg));
+	rw_wlock(&mr_lock);
+	ret = mem_range_softc.mr_op->set(&mem_range_softc, mrd, arg);
+	rw_wunlock(&mr_lock);
+	return (ret);
 }