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Date: Tue, 1 May 2012 17:57:58 -0600
From: Bjorn Helgaas <bhelgaas@...gle.com>
To: Yinghai Lu <yinghai@...nel.org>
Cc: Jesse Barnes <jbarnes@...tuousgeek.org>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Tony Luck <tony.luck@...el.com>,
David Miller <davem@...emloft.net>, x86 <x86@...nel.org>,
Dominik Brodowski <linux@...inikbrodowski.net>,
Andrew Morton <akpm@...ux-foundation.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arch@...r.kernel.org
Subject: Re: [PATCH -v11 17/30] resources: Add probe_resource()
On Sun, Mar 18, 2012 at 11:42 PM, Yinghai Lu <yinghai@...nel.org> wrote:
> It is changed from busn_res only version, because Bjorn found that version
> was not holding resource_lock.
> Even it may be ok for busn_res not holding resource_lock.
> It would be better to have it to be generic and use lock and we would
> use it for other resources.
>
> probe_resource() will try to find specified size or more in parent bus.
> If can not find current parent resource, and it will try to expand parents
> top.
> If still can not find that specified on top, it will try to reduce target size
> until find one.
>
> It will return 0, if it find any resource that it could use.
>
> Returned resource already register in the tree.
>
> So caller may still need call resource_replace to put real resource in
> the tree.
>
> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> ---
> include/linux/ioport.h | 7 ++
> kernel/resource.c | 160 ++++++++++++++++++++++++++++++++++++++++++++++--
> 2 files changed, 162 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/ioport.h b/include/linux/ioport.h
> index e885ba2..20a30df 100644
> --- a/include/linux/ioport.h
> +++ b/include/linux/ioport.h
> @@ -156,6 +156,13 @@ extern int allocate_resource(struct resource *root, struct resource *new,
> resource_size_t,
> resource_size_t),
> void *alignf_data);
> +void resource_shrink_parents_top(struct resource *b_res,
> + long size, struct resource *parent_res);
> +struct device;
> +int probe_resource(struct resource *b_res,
> + struct device *dev, struct resource *busn_res,
> + resource_size_t needed_size, struct resource **p,
> + int skip_nr, int limit, char *name);
This interface is a mess. I have a vague impression that this is
supposed to figure out whether a resource can be expanded, but why
does it need a struct device *? (I can read the code and see how you
use it, but it just doesn't fit in the resource abstraction.)
Supplying one struct resource * makes sense, but you have three. A
char * name? What's skip_nr? This just doesn't make sense to me.
I think you need a simpler, more general interface. update_resource()
seems OK to me -- it's pretty straightforward and has an obvious
meaning. Maybe you can make a resource_expand() or something that
just expands a resource in both directions as far as possible (until
it hits a sibling or the parent limits). Then you would know the
maximum possible size, and you could use update_resource() to shrink
it again and give up anything you don't need.
I spent most of the day merging the patches up to this point, and they
mostly make sense, but this one and the following ones are beyond my
ken, so I gave up.
> struct resource *lookup_resource(struct resource *root, resource_size_t start);
> int adjust_resource(struct resource *res, resource_size_t start,
> resource_size_t size);
> diff --git a/kernel/resource.c b/kernel/resource.c
> index 7640b3a..0c9616f 100644
> --- a/kernel/resource.c
> +++ b/kernel/resource.c
> @@ -521,14 +521,14 @@ out:
> * @alignf: alignment function, optional, called if not NULL
> * @alignf_data: arbitrary data to pass to the @alignf function
> */
> -int allocate_resource(struct resource *root, struct resource *new,
> +static int __allocate_resource(struct resource *root, struct resource *new,
> resource_size_t size, resource_size_t min,
> resource_size_t max, resource_size_t align,
> resource_size_t (*alignf)(void *,
> const struct resource *,
> resource_size_t,
> resource_size_t),
> - void *alignf_data)
> + void *alignf_data, bool lock)
> {
> int err;
> struct resource_constraint constraint;
> @@ -542,19 +542,33 @@ int allocate_resource(struct resource *root, struct resource *new,
> constraint.alignf = alignf;
> constraint.alignf_data = alignf_data;
>
> - if ( new->parent ) {
> + if (new->parent && lock) {
> /* resource is already allocated, try reallocating with
> the new constraints */
> return reallocate_resource(root, new, size, &constraint);
> }
>
> - write_lock(&resource_lock);
> + if (lock)
> + write_lock(&resource_lock);
> err = find_resource(root, new, size, &constraint);
> if (err >= 0 && __request_resource(root, new))
> err = -EBUSY;
> - write_unlock(&resource_lock);
> + if (lock)
> + write_unlock(&resource_lock);
> return err;
> }
> +int allocate_resource(struct resource *root, struct resource *new,
> + resource_size_t size, resource_size_t min,
> + resource_size_t max, resource_size_t align,
> + resource_size_t (*alignf)(void *,
> + const struct resource *,
> + resource_size_t,
> + resource_size_t),
> + void *alignf_data)
> +{
> + return __allocate_resource(root, new, size, min, max, align,
> + alignf, alignf_data, true);
> +}
>
> EXPORT_SYMBOL(allocate_resource);
>
> @@ -962,6 +976,142 @@ void __release_region(struct resource *parent, resource_size_t start,
> }
> EXPORT_SYMBOL(__release_region);
>
> +static void __resource_update_parents_top(struct resource *b_res,
> + long size, struct resource *parent_res)
> +{
> + struct resource *res = b_res;
> +
> + if (!size)
> + return;
> +
> + while (res) {
> + if (res == parent_res)
> + break;
> + res->end += size;
> + res = res->parent;
> + }
> +}
> +
> +static void __resource_extend_parents_top(struct resource *b_res,
> + long size, struct resource *parent_res)
> +{
> + __resource_update_parents_top(b_res, size, parent_res);
> +}
> +
> +void resource_shrink_parents_top(struct resource *b_res,
> + long size, struct resource *parent_res)
> +{
> + write_lock(&resource_lock);
> + __resource_update_parents_top(b_res, -size, parent_res);
> + write_unlock(&resource_lock);
> +}
> +
> +static resource_size_t __find_res_top_free_size(struct resource *res)
> +{
> + resource_size_t n_size;
> + struct resource tmp_res;
> +
> + /*
> + * find out number below res->end, that we can use at first
> + * res->start can not be used.
> + */
> + n_size = resource_size(res) - 1;
> + memset(&tmp_res, 0, sizeof(struct resource));
> + while (n_size > 0) {
> + int ret;
> +
> + ret = __allocate_resource(res, &tmp_res, n_size,
> + res->end - n_size + 1, res->end,
> + 1, NULL, NULL, false);
> + if (ret == 0) {
> + __release_resource(&tmp_res);
> + break;
> + }
> + n_size--;
> + }
> +
> + return n_size;
> +}
> +
> +int probe_resource(struct resource *b_res,
> + struct device *dev, struct resource *busn_res,
> + resource_size_t needed_size, struct resource **p,
> + int skip_nr, int limit, char *name)
> +{
> + int ret = -ENOMEM;
> + resource_size_t n_size;
> + struct resource *parent_res = NULL;
> + resource_size_t tmp = b_res->end + 1;
> +
> +again:
> + /*
> + * find biggest range in b_res that we can use in the middle
> + * and we can not use some spots from start of b_res.
> + */
> + n_size = resource_size(b_res);
> + if (n_size > skip_nr)
> + n_size -= skip_nr;
> + else
> + n_size = 0;
> +
> + memset(busn_res, 0, sizeof(struct resource));
> + dev_printk(KERN_DEBUG, dev, "find free %s in res: %pR\n", name, b_res);
> + while (n_size >= needed_size) {
> + ret = allocate_resource(b_res, busn_res, n_size,
> + b_res->start + skip_nr, b_res->end,
> + 1, NULL, NULL);
> + if (!ret)
> + return ret;
> + n_size--;
> + }
> +
> + /* try extend the top of parent bus, find free under top at first */
> + write_lock(&resource_lock);
> + n_size = __find_res_top_free_size(b_res);
> + dev_printk(KERN_DEBUG, dev, "found free %s %ld in res: %pR top\n",
> + name, (unsigned long)n_size, b_res);
> +
> + /* can not extend cross local boundary */
> + if ((limit - b_res->end) < (needed_size - n_size))
> + goto reduce_needed_size;
> +
> + /* find extended range */
> + memset(busn_res, 0, sizeof(struct resource));
> + parent_res = b_res;
> + while (parent_res) {
> + ret = __allocate_resource(parent_res, busn_res,
> + needed_size - n_size,
> + tmp, tmp + needed_size - n_size - 1,
> + 1, NULL, NULL, false);
> + if (!ret) {
> + /* save parent_res, we need it as stopper later */
> + *p = parent_res;
> +
> + /* prepare busn_res for return */
> + __release_resource(busn_res);
> + busn_res->start -= n_size;
> +
> + /* extend parent bus top*/
> + __resource_extend_parents_top(b_res,
> + needed_size - n_size, parent_res);
> + __request_resource(b_res, busn_res);
> +
> + write_unlock(&resource_lock);
> + return ret;
> + }
> + parent_res = parent_res->parent;
> + }
> +
> +reduce_needed_size:
> + write_unlock(&resource_lock);
> + /* ret must not be 0 here */
> + needed_size--;
> + if (needed_size)
> + goto again;
> +
> + return ret;
> +}
> +
> /*
> * Managed region resource
> */
> --
> 1.7.7
>
--
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