Re: [PATCH 2.6.12-rc4 1/3] dynamic sysfs callbacks

[Yani Ioannou <yani.ioannou@gmail.com>]

That just looks like a subset of the core patch except for the
member's name and the bin_attribute change I didn't notice (which
looks very useful), so yes that is good (although I don't see any
reason to change the name).

Truth is after looking at how all the sysfs derived attributes are
used its hard not to believe that all the attributes should be changed
for exactly the same reasons as device_attribute. For example my patch
against net-sysfs.c uses class_attributes, and that cleans up the code
nicely and saves space. What attribute type wouldn't benefit from this
change? I know its a lot of work to change the driver's to benefit
from it but it breaks nothing in the mean-time and I'm committed to
doing a fair bit of that work if need be.

If you think the patch should be split up more and incrementally
implemented I can understand that, but we obviously need to change the
derived attributes eventually to make use of it, why not now? It
doesn't really break anything, my large update is just to remove the
harmless warnings.

Thanks,
Yani

On 5/10/05, Greg KH <greg@kroah.com> wrote:
> On Sat, May 07, 2005 at 09:21:34AM -0400, Yani Ioannou wrote:
> > Hi,
> >
> > This patch against 2.6.12-rc4 adds a void * field to the base sysfs
> > attribute, and updates all the derived attributes (device_attribute,
> > etc) to pass the void * to their sysfs callbacks. This facilitates a
> > number of things:
> 
> Woah.  Why change _every_ type of attribute callback?  Why not only
> change the ones that actually need this kind of change?  That would
> reduce your patch immensly, and allow us to actually see what is going
> on.
> 
> And, in looking at the attribute structure, I see we already have a
> private pointer in the bin_attribute structure, so we might as well
> collapse them together.
> 
> So, here's a first patch to base your next changes off of.  It merely
> adds a private pointer to the struct attribute.  It breaks no code, and
> requires no other changes to get it to work properly.  Can you now work
> off of it and start changing _only_ the attribute types that need this
> change for now?  That should reduce your changes a lot.  I'll add this
> patch to my quilt tree so it will show up in the next -mm releases.
> 
> thanks,
> 
> greg k-h
> 
> Subject: sysfs: make attribute contain a private pointer.
> 
> Lets us get rid of the bin_attribute's pointer at the same time.
> This is being done so that sysfs code can determine what attribute is being
> accessed to allow smaller amounts of kernel code to be written.
> 
> Based on a patch from Yani Ioannou <yani.ioannou@gmail.com>
> 
> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
> 
> ---
>  drivers/pci/pci-sysfs.c |    4 ++--
>  include/linux/sysfs.h   |   30 ++++++++++++++++++++----------
>  2 files changed, 22 insertions(+), 12 deletions(-)
> 
> --- gregkh-2.6.orig/include/linux/sysfs.h       2005-05-10 14:15:04.000000000 -0700
> +++ gregkh-2.6/include/linux/sysfs.h    2005-05-10 15:10:31.000000000 -0700
> @@ -18,6 +18,7 @@
>  struct attribute {
>         const char              * name;
>         struct module           * owner;
> +       void                    * private;
>         mode_t                  mode;
>  };
> 
> @@ -33,15 +34,25 @@
>   * for examples..
>   */
> 
> -#define __ATTR(_name,_mode,_show,_store) { \
> -       .attr = {.name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE },     \
> -       .show   = _show,                                        \
> -       .store  = _store,                                       \
> -}
> -
> -#define __ATTR_RO(_name) { \
> -       .attr   = { .name = __stringify(_name), .mode = 0444, .owner = THIS_MODULE },   \
> -       .show   = _name##_show, \
> +#define __ATTR(_name,_mode,_show,_store) {     \
> +       .attr = {                               \
> +               .name = __stringify(_name),     \
> +               .mode = _mode,                  \
> +               .private = NULL,                \
> +               .owner = THIS_MODULE,           \
> +       },                                      \
> +       .show   = _show,                        \
> +       .store  = _store,                       \
> +}
> +
> +#define __ATTR_RO(_name) {                     \
> +       .attr   = {                             \
> +               .name = __stringify(_name),     \
> +               .mode = 0444,                   \
> +               .private = NULL,                \
> +               .owner = THIS_MODULE,           \
> +       },                                      \
> +       .show   = _name##_show,                 \
>  }
> 
>  #define __ATTR_NULL { .attr = { .name = NULL } }
> @@ -53,7 +64,6 @@
>  struct bin_attribute {
>         struct attribute        attr;
>         size_t                  size;
> -       void                    *private;
>         ssize_t (*read)(struct kobject *, char *, loff_t, size_t);
>         ssize_t (*write)(struct kobject *, char *, loff_t, size_t);
>         int (*mmap)(struct kobject *, struct bin_attribute *attr,
> --- gregkh-2.6.orig/drivers/pci/pci-sysfs.c     2005-05-10 14:15:04.000000000 -0700
> +++ gregkh-2.6/drivers/pci/pci-sysfs.c  2005-05-10 15:06:29.000000000 -0700
> @@ -299,7 +299,7 @@
>  {
>         struct pci_dev *pdev = to_pci_dev(container_of(kobj,
>                                                        struct device, kobj));
> -       struct resource *res = (struct resource *)attr->private;
> +       struct resource *res = (struct resource *)attr->attr.private;
>         enum pci_mmap_state mmap_type;
> 
>         vma->vm_pgoff += res->start >> PAGE_SHIFT;
> @@ -337,9 +337,9 @@
>                         res_attr->attr.name = res_attr_name;
>                         res_attr->attr.mode = S_IRUSR | S_IWUSR;
>                         res_attr->attr.owner = THIS_MODULE;
> +                       res_attr->attr.private = &pdev->resource[i];
>                         res_attr->size = pci_resource_len(pdev, i);
>                         res_attr->mmap = pci_mmap_resource;
> -                       res_attr->private = &pdev->resource[i];
>                         sysfs_create_bin_file(&pdev->dev.kobj, res_attr);
>                 }
>         }
>