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    Subject[PATCH 5/9] Revert "resources: support allocating space within a region from the top down"
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    Date

    This reverts commit e7f8567db9a7f6b3151b0b275e245c1cef0d9c70.

    Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
    ---

    Documentation/kernel-parameters.txt | 5 --
    include/linux/ioport.h | 1
    kernel/resource.c | 98 +----------------------------------
    3 files changed, 4 insertions(+), 100 deletions(-)


    diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
    index cdd2a6e..8b61c93 100644
    --- a/Documentation/kernel-parameters.txt
    +++ b/Documentation/kernel-parameters.txt
    @@ -2175,11 +2175,6 @@ and is between 256 and 4096 characters. It is defined in the file
    reset_devices [KNL] Force drivers to reset the underlying device
    during initialization.

    - resource_alloc_from_bottom
    - Allocate new resources from the beginning of available
    - space, not the end. If you need to use this, please
    - report a bug.
    -
    resume= [SWSUSP]
    Specify the partition device for software suspend

    diff --git a/include/linux/ioport.h b/include/linux/ioport.h
    index d377ea8..b227902 100644
    --- a/include/linux/ioport.h
    +++ b/include/linux/ioport.h
    @@ -112,7 +112,6 @@ struct resource_list {
    /* PC/ISA/whatever - the normal PC address spaces: IO and memory */
    extern struct resource ioport_resource;
    extern struct resource iomem_resource;
    -extern int resource_alloc_from_bottom;

    extern struct resource *request_resource_conflict(struct resource *root, struct resource *new);
    extern int request_resource(struct resource *root, struct resource *new);
    diff --git a/kernel/resource.c b/kernel/resource.c
    index 9fad33e..560659f 100644
    --- a/kernel/resource.c
    +++ b/kernel/resource.c
    @@ -40,23 +40,6 @@ EXPORT_SYMBOL(iomem_resource);

    static DEFINE_RWLOCK(resource_lock);

    -/*
    - * By default, we allocate free space bottom-up. The architecture can request
    - * top-down by clearing this flag. The user can override the architecture's
    - * choice with the "resource_alloc_from_bottom" kernel boot option, but that
    - * should only be a debugging tool.
    - */
    -int resource_alloc_from_bottom = 1;
    -
    -static __init int setup_alloc_from_bottom(char *s)
    -{
    - printk(KERN_INFO
    - "resource: allocating from bottom-up; please report a bug\n");
    - resource_alloc_from_bottom = 1;
    - return 0;
    -}
    -early_param("resource_alloc_from_bottom", setup_alloc_from_bottom);
    -
    static void *r_next(struct seq_file *m, void *v, loff_t *pos)
    {
    struct resource *p = v;
    @@ -397,74 +380,7 @@ static bool resource_contains(struct resource *res1, struct resource *res2)
    }

    /*
    - * Find the resource before "child" in the sibling list of "root" children.
    - */
    -static struct resource *find_sibling_prev(struct resource *root, struct resource *child)
    -{
    - struct resource *this;
    -
    - for (this = root->child; this; this = this->sibling)
    - if (this->sibling == child)
    - return this;
    -
    - return NULL;
    -}
    -
    -/*
    - * Find empty slot in the resource tree given range and alignment.
    - * This version allocates from the end of the root resource first.
    - */
    -static int find_resource_from_top(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)
    -{
    - struct resource *this;
    - struct resource tmp, avail, alloc;
    -
    - tmp.start = root->end;
    - tmp.end = root->end;
    -
    - this = find_sibling_prev(root, NULL);
    - for (;;) {
    - if (this) {
    - if (this->end < root->end)
    - tmp.start = this->end + 1;
    - } else
    - tmp.start = root->start;
    -
    - resource_clip(&tmp, min, max);
    -
    - /* Check for overflow after ALIGN() */
    - avail = *new;
    - avail.start = ALIGN(tmp.start, align);
    - avail.end = tmp.end;
    - if (avail.start >= tmp.start) {
    - alloc.start = alignf(alignf_data, &avail, size, align);
    - alloc.end = alloc.start + size - 1;
    - if (resource_contains(&avail, &alloc)) {
    - new->start = alloc.start;
    - new->end = alloc.end;
    - return 0;
    - }
    - }
    -
    - if (!this || this->start == root->start)
    - break;
    -
    - tmp.end = this->start - 1;
    - this = find_sibling_prev(root, this);
    - }
    - return -EBUSY;
    -}
    -
    -/*
    * Find empty slot in the resource tree given range and alignment.
    - * This version allocates from the beginning of the root resource first.
    */
    static int find_resource(struct resource *root, struct resource *new,
    resource_size_t size, resource_size_t min,
    @@ -480,15 +396,14 @@ static int find_resource(struct resource *root, struct resource *new,

    tmp.start = root->start;
    /*
    - * Skip past an allocated resource that starts at 0, since the
    - * assignment of this->start - 1 to tmp->end below would cause an
    - * underflow.
    + * Skip past an allocated resource that starts at 0, since the assignment
    + * of this->start - 1 to tmp->end below would cause an underflow.
    */
    if (this && this->start == 0) {
    tmp.start = this->end + 1;
    this = this->sibling;
    }
    - for (;;) {
    + for(;;) {
    if (this)
    tmp.end = this->start - 1;
    else
    @@ -509,10 +424,8 @@ static int find_resource(struct resource *root, struct resource *new,
    return 0;
    }
    }
    -
    if (!this)
    break;
    -
    tmp.start = this->end + 1;
    this = this->sibling;
    }
    @@ -545,10 +458,7 @@ int allocate_resource(struct resource *root, struct resource *new,
    alignf = simple_align_resource;

    write_lock(&resource_lock);
    - if (resource_alloc_from_bottom)
    - err = find_resource(root, new, size, min, max, align, alignf, alignf_data);
    - else
    - err = find_resource_from_top(root, new, size, min, max, align, alignf, alignf_data);
    + err = find_resource(root, new, size, min, max, align, alignf, alignf_data);
    if (err >= 0 && __request_resource(root, new))
    err = -EBUSY;
    write_unlock(&resource_lock);


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