newbus: Move from bus_child_{pnpinfo,location}_src to bus_child_{pnpinfo,location} with sbuf

Now that the upper layers all go through a layer to tie into these
information functions that translates an sbuf into char * and len. The
current interface suffers issues of what to do in cases of truncation,
etc. Instead, migrate all these functions to using struct sbuf and these
issues go away. The caller is also in charge of any memory allocation
and/or expansion that's needed during this process.

Create a bus_generic_child_{pnpinfo,location} and make it default. It
just returns success. This is for those busses that have no information
for these items. Migrate the now-empty routines to using this as
appropriate.

Document these new interfaces with man pages, and oversight from before.

Reviewed by:		jhb, bcr
Sponsored by:		Netflix
Differential Revision:	https://reviews.freebsd.org/D29937

1 files changed, 4 insertions, 9 deletions

diff --git a/sys/dev/nvdimm/nvdimm_acpi.c b/sys/dev/nvdimm/nvdimm_acpi.c
index ccb5dd048210..11c93ad29fdb 100644
--- a/sys/dev/nvdimm/nvdimm_acpi.c
+++ b/sys/dev/nvdimm/nvdimm_acpi.c
@@ -41,6 +41,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/lock.h>
 #include <sys/malloc.h>
 #include <sys/module.h>
+#include <sys/sbuf.h>
 #include <sys/uuid.h>
 
 #include <contrib/dev/acpica/include/acpi.h>
@@ -245,20 +246,14 @@ nvdimm_root_write_ivar(device_t dev, device_t child, int index,
 }
 
 static int
-nvdimm_root_child_location_str(device_t dev, device_t child, char *buf,
-    size_t buflen)
+nvdimm_root_child_location(device_t dev, device_t child, struct sbuf *sb)
 {
 	ACPI_HANDLE handle;
-	int res;
 
 	handle = nvdimm_root_get_acpi_handle(child);
 	if (handle != NULL)
-		res = snprintf(buf, buflen, "handle=%s", acpi_name(handle));
-	else
-		res = snprintf(buf, buflen, "");
+		sbuf_printf(sb, "handle=%s", acpi_name(handle));
 
-	if (res >= buflen)
-		return (EOVERFLOW);
 	return (0);
 }
 
@@ -269,7 +264,7 @@ static device_method_t nvdimm_acpi_methods[] = {
 	DEVMETHOD(bus_add_child, bus_generic_add_child),
 	DEVMETHOD(bus_read_ivar, nvdimm_root_read_ivar),
 	DEVMETHOD(bus_write_ivar, nvdimm_root_write_ivar),
-	DEVMETHOD(bus_child_location_str, nvdimm_root_child_location_str),
+	DEVMETHOD(bus_child_location, nvdimm_root_child_location),
 	DEVMETHOD_END
 };