Re: [PATCH 1/5] dynamic logical partitioning infrastructure

Michael Ellerman wrote:

On Fri, 2009-09-11 at 16:10 -0500, Nathan Fontenot wrote:

quoted

This patch provides the kernel DLPAR infrastructure in a new filed named
dlpar.c.  The functionality provided is for acquiring and releasing a resource from firmware and the parsing of information returned from the
ibm,configure-connector rtas call.  Additionally this exports the pSeries reconfiguration notifier chain so that it can be invoked when
device tree updates are made.

Signed-off-by: Nathan Fontenot <redacted>
---

Index: powerpc/arch/powerpc/platforms/pseries/dlpar.c
===================================================================

--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ powerpc/arch/powerpc/platforms/pseries/dlpar.c	2009-09-11 12:51:52.000000000 -0500

@@ -0,0 +1,416 @@
+/*
+ * dlpar.c - support for dynamic reconfiguration (including PCI
+ * Hotplug and Dynamic Logical Partitioning on RPA platforms).
+ *
+ * Copyright (C) 2009 Nathan Fontenot
+ * Copyright (C) 2009 IBM Corporation
+ *
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/kref.h>
+#include <linux/notifier.h>
+#include <linux/proc_fs.h>
+#include <linux/spinlock.h>
+
+#include <asm/prom.h>
+#include <asm/machdep.h>
+#include <asm/uaccess.h>
+#include <asm/rtas.h>
+#include <asm/pSeries_reconfig.h>
+
+#define CFG_CONN_WORK_SIZE	4096
+static char workarea[CFG_CONN_WORK_SIZE];
+spinlock_t workarea_lock;
+
+static struct property *parse_cc_property(char *workarea)
+{
+	struct property *prop;
+	u32 *work_ints;
+	char *name;
+	char *value;
+
+	prop = kzalloc(sizeof(*prop), GFP_KERNEL);
+	if (!prop)
+		return NULL;
+
+	work_ints = (u32 *)workarea;
+	name = workarea + work_ints[2];
+	prop->name = kzalloc(strlen(name) + 1, GFP_KERNEL);
+	if (!prop->name) {
+		kfree(prop);
+		return NULL;
+	}
+
+	strcpy(prop->name, name);
+
+	prop->length = work_ints[3];
+	value = workarea + work_ints[4];
+	prop->value = kzalloc(prop->length, GFP_KERNEL);

The use of work_ints is a bit opaque, it might be clearer if you define
a struct, something like:

struct cc_prop {
	u32 ?;
	u32 ?;
	u32 name_offset;
	u32 length;
	u32 value_offset;
};

cc = (struct cc_prop *)workarea;

name = workarea + cc->name_offset;
..
prop->length = cc->length;
value = workarea + cc->value_offset;

Good idea, and I agree that the use of the workarea/work_ints is a bit vague.
The current way works because sometimes its easier to think of the workarea
as a char buffer and sometimes as a int buffer.

I'll try to come up with something to make the parsing of the workarea buffer
easier to understand.

-Nathan Fontenot

etc.


Also I don't see any checking of the offsets into workarea (for name &
value), vs the size of workarea.

cheers