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

[Nathan Fontenot]

Michael Ellerman wrote:
> On Fri, 2009-09-11 at 16:10 -0500, Nathan Fontenot wrote:
> > 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 <nfont@xxxxxxxxxxxxxx>
> > ---
> >
> > 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
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