[Xen-devel] Re: [PATCH 2.6.12.6-xen] sysfs attributes for xen

[Greg KH <greg@xxxxxxxxx>]

> linux-2.6-xen-sparse/arch/xen/kernel/xen_sysfs.c
> --- /dev/null Fri Jan 27 11:48:32 2006
> +++ b/linux-2.6-xen-sparse/arch/xen/kernel/xen_sysfs.c        Fri Jan 27 
> 14:28:42 
> 2006
> @@ -0,0 +1,73 @@
> +/* 
> +    copyright (c) 2006 IBM Corporation 
> +    Mike Day <ncmike@xxxxxxxxxx>

Wrong copyright notice as per the IBM lawyers :)

> +
> +    This program is free software; you can redistribute it and/or modify
> +    it under the terms of the GNU General Public License as published by
> +    the Free Software Foundation; either version 2 of the License, or
> +    (at your option) any later version.

Are you sure about the version 2 or later?

> +
> +    This program is distributed in the hope that it will be useful,
> +    but WITHOUT ANY WARRANTY; without even the implied warranty of
> +    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +    GNU General Public License for more details.
> +
> +    You should have received a copy of the GNU General Public License
> +    along with this program; if not, write to the Free Software
> +    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  
> USA

These two paragraphs are not needed.

> +*/
> +
> +
> +
> +#include <linux/config.h>
> +#include <linux/kernel.h>
> +#include <linux/init.h>
> +#include <linux/kobject.h>
> +#include <linux/sysfs.h>
> +
> +#include <asm-xen/xen_sysfs.h>
> +
> +
> +static struct subsystem hypervisor_subsys = {
> +     .kset = {
> +             .kobj = {
> +                      .name = "hypervisor",
> +              },
> +     },
> +};

No, use the proper macros that define this for you.

> +
> +static struct kset xen_kset = {
> +
> +     .kobj = {
> +             .name = "xen",
> +     },
> +};

Why are you createing a xen kset?  You should not have to do this.

> +
> +struct subsystem * 
> +get_hyper_subsys(void) 
> +{
> +     return &hypervisor_subsys;
> +}

What does this do?  Just make the hypervisor subsystem structure global
like the rest of the kernel's subsystems are that need this.

> +
> +
> +struct kset *
> +get_xen_kset(void)
> +{
> +     return &xen_kset;
> +}

Again, not needed.

> +
> +int __init
> +hyper_sysfs_init(void)
> +{
> +     int err ;
> +     
> +     if( 0 ==  (err = subsystem_register(&hypervisor_subsys)) ) {
> +             xen_kset.subsys = &hypervisor_subsys;
> +             err = kset_register(&xen_kset);
> +     }

Is this the xen coding style?  If so, it's got to change before making
it into mainline...  Please fix this up.

Also, don't use a xen kset.  Make it a subsystem.  Life is much easier
that way.

> +/* xen version info */
> +static ssize_t xen_version_show(struct kobject * kobj, 
> +                             struct attribute * attr, 
> +                             char *page)

Trailing spaces here, and in a lot of other places in your patch.
Please clean them up (there are automatic tools that do this for you...)

> +{
> +     long version;
> +     long major, minor;
> +     char extra_version[16];
> +     
> +     if ( (version = HYPERVISOR_xen_version(XENVER_version, NULL)) ) {

Do not do assignments within if statments.  It's generally considered bad
form.  Also the spacing is wrong, but I know you will fix that up for
the rest of the patch too, so I'll just not mention it in every place.

> +             
> +             major = version >> 16;
> +             minor = version & 0xff;
> +             if( ! HYPERVISOR_xen_version(XENVER_extraversion, 
> +                                         extra_version) ) {
> +                     page[PAGE_SIZE - 1] = 0x00;

Not needed.

> +                     return snprintf(page, PAGE_SIZE - 1, 
> +                                     "xen-%ld.%ld%s\n",
> +                                     major, minor, extra_version);
> +             }
> +     }
> +     return 0;

Why not return an error number if this isn't successful?

> +}
> +
> +static struct xen_attr xen_ver_attr = {
> +     .attr = {
> +             .name = "version", 
> +             .mode = 0444, 
> +             .owner = THIS_MODULE, 
> +     },
> +     .show = xen_version_show,
> +};

Please use the proper macros to create these, do NOT do it by hand.

> +
> +static struct kobject xen_ver_obj = {
> +     .name = "version",
> +};

Wow, a static kobject.  Hint, not a good thing to do for a dynamic
thing.  This is not how you create a new attribute.

> +
> +/* xen compile info */
> +static ssize_t xen_compile_show(struct kobject * kobj, 
> +                             struct attribute * attr, 
> +                             char * page)
> +{
> +     struct xen_compile_info info;
> +     
> +     if( 0 == HYPERVISOR_xen_version(XENVER_compile_info, &info) ) {
> +             page[PAGE_SIZE - 1] = 0x00;

I'll not point this out again...

> +             return snprintf(page, PAGE_SIZE - 1, 
> +                             "compiled by %s, using %s, on %s\n", 
> +                             info.compile_by, 
> +                             info.compile_date, 
> +                             info.compiler);
> +     }
> +     return 0;

Nor this...

> +static struct xen_attr xen_compile_attr = {
> +     .attr = {
> +             .name = "compilation", 
> +             .mode = 0444, 
> +             .owner = THIS_MODULE, 
> +     },
> +     .show = xen_compile_show,
> +};

Nor this...

> +static struct kobject xen_compile_obj = {
> +     .name = "compilation",
> +};

Or this...

> linux-2.6-xen-sparse/include/asm-xen/xen_sysfs.h
> --- /dev/null Fri Jan 27 11:48:32 2006
> +++ b/linux-2.6-xen-sparse/include/asm-xen/xen_sysfs.h        Fri Jan 27 
> 14:28:42 
> 2006
> @@ -0,0 +1,45 @@
> +/* 
> +    copyright (c) 2006 IBM Corporation 
> +    Mike Day <ncmike@xxxxxxxxxx>
> +
> +    This program is free software; you can redistribute it and/or modify
> +    it under the terms of the GNU General Public License as published by
> +    the Free Software Foundation; either version 2 of the License, or
> +    (at your option) any later version.
> +
> +    This program is distributed in the hope that it will be useful,
> +    but WITHOUT ANY WARRANTY; without even the implied warranty of
> +    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +    GNU General Public License for more details.
> +
> +    You should have received a copy of the GNU General Public License
> +    along with this program; if not, write to the Free Software
> +    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  
> USA
> +*/
> +
> +
> +
> +#ifndef _XEN_SYSFS_H_
> +#define _XEN_SYSFS_H_
> +
> +#ifdef __KERNEL__ 

Is this really needed?  Would an userspace program ever need this?

> +
> +#include <linux/kobject.h>
> +#include <linux/sysfs.h>
> +#include <linux/module.h>

Not needed for this header file

> +#include <asm-xen/asm/hypercall.h>
> +#include <asm-xen/xen-public/version.h>

Nor these.

> +struct xen_attr {
> +     struct attribute attr;
> +     ssize_t (*show)(struct kobject *, struct attribute *, char *);
> +     ssize_t (*store)(struct kobject *, struct attribute *, char *);
> +};
> +
> +extern int HYPERVISOR_xen_version(int, void*);

Shouldn't this be declared somewhere else?

> +extern struct subsystem * get_hyper_subsys(void);
> +extern struct kset * get_xen_kset(void);

Not needed at all.

Hm, is this file even needed?

thanks,

greg k-h

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