OSCL-LXR linux-6.0.1/​kernel/​resource.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  *  linux/kernel/resource.c
  *
  * Copyright (C) 1999   Linus Torvalds
  * Copyright (C) 1999   Martin Mares <mj@ucw.cz>
  *
  * Arbitrary resource management.
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/export.h>
 #include <linux/errno.h>
 #include <linux/ioport.h>
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <linux/fs.h>
 #include <linux/proc_fs.h>
 #include <linux/pseudo_fs.h>
 #include <linux/sched.h>
 #include <linux/seq_file.h>
 #include <linux/device.h>
 #include <linux/pfn.h>
 #include <linux/mm.h>
 #include <linux/mount.h>
 #include <linux/resource_ext.h>
 #include <uapi/linux/magic.h>
 #include <asm/io.h>
 
 
 struct resource ioport_resource = {
     .name   = "PCI IO",
     .start  = 0,
     .end    = IO_SPACE_LIMIT,
     .flags  = IORESOURCE_IO,
 };
 EXPORT_SYMBOL(ioport_resource);
 
 struct resource iomem_resource = {
     .name   = "PCI mem",
     .start  = 0,
     .end    = -1,
     .flags  = IORESOURCE_MEM,
 };
 EXPORT_SYMBOL(iomem_resource);
 
 /* constraints to be met while allocating resources */
 struct resource_constraint {
     resource_size_t min, max, align;
     resource_size_t (*alignf)(void *, const struct resource *,
             resource_size_t, resource_size_t);
     void *alignf_data;
 };
 
 static DEFINE_RWLOCK(resource_lock);
 
 static struct resource *next_resource(struct resource *p)
 {
     if (p->child)
         return p->child;
     while (!p->sibling && p->parent)
         p = p->parent;
     return p->sibling;
 }
 
 static struct resource *next_resource_skip_children(struct resource *p)
 {
     while (!p->sibling && p->parent)
         p = p->parent;
     return p->sibling;
 }
 
 #define for_each_resource(_root, _p, _skip_children) \
     for ((_p) = (_root)->child; (_p); \
          (_p) = (_skip_children) ? next_resource_skip_children(_p) : \
                        next_resource(_p))
 
 static void *r_next(struct seq_file *m, void *v, loff_t *pos)
 {
     struct resource *p = v;
     (*pos)++;
     return (void *)next_resource(p);
 }
 
 #ifdef CONFIG_PROC_FS
 
 enum { MAX_IORES_LEVEL = 5 };
 
 static void *r_start(struct seq_file *m, loff_t *pos)
     __acquires(resource_lock)
 {
     struct resource *p = pde_data(file_inode(m->file));
     loff_t l = 0;
     read_lock(&resource_lock);
     for (p = p->child; p && l < *pos; p = r_next(m, p, &l))
         ;
     return p;
 }
 
 static void r_stop(struct seq_file *m, void *v)
     __releases(resource_lock)
 {
     read_unlock(&resource_lock);
 }
 
 static int r_show(struct seq_file *m, void *v)
 {
     struct resource *root = pde_data(file_inode(m->file));
     struct resource *r = v, *p;
     unsigned long long start, end;
     int width = root->end < 0x10000 ? 4 : 8;
     int depth;
 
     for (depth = 0, p = r; depth < MAX_IORES_LEVEL; depth++, p = p->parent)
         if (p->parent == root)
             break;
 
     if (file_ns_capable(m->file, &init_user_ns, CAP_SYS_ADMIN)) {
         start = r->start;
         end = r->end;
     } else {
         start = end = 0;
     }
 
     seq_printf(m, "%*s%0*llx-%0*llx : %s\n",
             depth * 2, "",
             width, start,
             width, end,
             r->name ? r->name : "<BAD>");
     return 0;
 }
 
 static const struct seq_operations resource_op = {
     .start  = r_start,
     .next   = r_next,
     .stop   = r_stop,
     .show   = r_show,
 };
 
 static int __init ioresources_init(void)
 {
     proc_create_seq_data("ioports", 0, NULL, &resource_op,
             &ioport_resource);
     proc_create_seq_data("iomem", 0, NULL, &resource_op, &iomem_resource);
     return 0;
 }
 __initcall(ioresources_init);
 
 #endif /* CONFIG_PROC_FS */
 
 static void free_resource(struct resource *res)
 {
     /**
      * If the resource was allocated using memblock early during boot
      * we'll leak it here: we can only return full pages back to the
      * buddy and trying to be smart and reusing them eventually in
      * alloc_resource() overcomplicates resource handling.
      */
     if (res && PageSlab(virt_to_head_page(res)))
         kfree(res);
 }
 
 static struct resource *alloc_resource(gfp_t flags)
 {
     return kzalloc(sizeof(struct resource), flags);
 }
 
 /* Return the conflict entry if you can't request it */
 static struct resource * __request_resource(struct resource *root, struct resource *new)
 {
     resource_size_t start = new->start;
     resource_size_t end = new->end;
     struct resource *tmp, **p;
 
     if (end < start)
         return root;
     if (start < root->start)
         return root;
     if (end > root->end)
         return root;
     p = &root->child;
     for (;;) {
         tmp = *p;
         if (!tmp || tmp->start > end) {
             new->sibling = tmp;
             *p = new;
             new->parent = root;
             return NULL;
         }
         p = &tmp->sibling;
         if (tmp->end < start)
             continue;
         return tmp;
     }
 }
 
 static int __release_resource(struct resource *old, bool release_child)
 {
     struct resource *tmp, **p, *chd;
 
     p = &old->parent->child;
     for (;;) {
         tmp = *p;
         if (!tmp)
             break;
         if (tmp == old) {
             if (release_child || !(tmp->child)) {
                 *p = tmp->sibling;
             } else {
                 for (chd = tmp->child;; chd = chd->sibling) {
                     chd->parent = tmp->parent;
                     if (!(chd->sibling))
                         break;
                 }
                 *p = tmp->child;
                 chd->sibling = tmp->sibling;
             }
             old->parent = NULL;
             return 0;
         }
         p = &tmp->sibling;
     }
     return -EINVAL;
 }
 
 static void __release_child_resources(struct resource *r)
 {
     struct resource *tmp, *p;
     resource_size_t size;
 
     p = r->child;
     r->child = NULL;
     while (p) {
         tmp = p;
         p = p->sibling;
 
         tmp->parent = NULL;
         tmp->sibling = NULL;
         __release_child_resources(tmp);
 
         printk(KERN_DEBUG "release child resource %pR\n", tmp);
         /* need to restore size, and keep flags */
         size = resource_size(tmp);
         tmp->start = 0;
         tmp->end = size - 1;
     }
 }
 
 void release_child_resources(struct resource *r)
 {
     write_lock(&resource_lock);
     __release_child_resources(r);
     write_unlock(&resource_lock);
 }
 
 /**
  * request_resource_conflict - request and reserve an I/O or memory resource
  * @root: root resource descriptor
  * @new: resource descriptor desired by caller
  *
  * Returns 0 for success, conflict resource on error.
  */
 struct resource *request_resource_conflict(struct resource *root, struct resource *new)
 {
     struct resource *conflict;
 
     write_lock(&resource_lock);
     conflict = __request_resource(root, new);
     write_unlock(&resource_lock);
     return conflict;
 }
 
 /**
  * request_resource - request and reserve an I/O or memory resource
  * @root: root resource descriptor
  * @new: resource descriptor desired by caller
  *
  * Returns 0 for success, negative error code on error.
  */
 int request_resource(struct resource *root, struct resource *new)
 {
     struct resource *conflict;
 
     conflict = request_resource_conflict(root, new);
     return conflict ? -EBUSY : 0;
 }
 
 EXPORT_SYMBOL(request_resource);
 
 /**
  * release_resource - release a previously reserved resource
  * @old: resource pointer
  */
 int release_resource(struct resource *old)
 {
     int retval;
 
     write_lock(&resource_lock);
     retval = __release_resource(old, true);
     write_unlock(&resource_lock);
     return retval;
 }
 
 EXPORT_SYMBOL(release_resource);
 
 /**
  * find_next_iomem_res - Finds the lowest iomem resource that covers part of
  *           [@start..@end].
  *
  * If a resource is found, returns 0 and @*res is overwritten with the part
  * of the resource that's within [@start..@end]; if none is found, returns
  * -ENODEV.  Returns -EINVAL for invalid parameters.
  *
  * @start:  start address of the resource searched for
  * @end:    end address of same resource
  * @flags:  flags which the resource must have
  * @desc:   descriptor the resource must have
  * @res:    return ptr, if resource found
  *
  * The caller must specify @start, @end, @flags, and @desc
  * (which may be IORES_DESC_NONE).
  */
 static int find_next_iomem_res(resource_size_t start, resource_size_t end,
                    unsigned long flags, unsigned long desc,
                    struct resource *res)
 {
     struct resource *p;
 
     if (!res)
         return -EINVAL;
 
     if (start >= end)
         return -EINVAL;
 
     read_lock(&resource_lock);
 
     for (p = iomem_resource.child; p; p = next_resource(p)) {
         /* If we passed the resource we are looking for, stop */
         if (p->start > end) {
             p = NULL;
             break;
         }
 
         /* Skip until we find a range that matches what we look for */
         if (p->end < start)
             continue;
 
         if ((p->flags & flags) != flags)
             continue;
         if ((desc != IORES_DESC_NONE) && (desc != p->desc))
             continue;
 
         /* Found a match, break */
         break;
     }
 
     if (p) {
         /* copy data */
         *res = (struct resource) {
             .start = max(start, p->start),
             .end = min(end, p->end),
             .flags = p->flags,
             .desc = p->desc,
             .parent = p->parent,
         };
     }
 
     read_unlock(&resource_lock);
     return p ? 0 : -ENODEV;
 }
 
 static int __walk_iomem_res_desc(resource_size_t start, resource_size_t end,
                  unsigned long flags, unsigned long desc,
                  void *arg,
                  int (*func)(struct resource *, void *))
 {
     struct resource res;
     int ret = -EINVAL;
 
     while (start < end &&
            !find_next_iomem_res(start, end, flags, desc, &res)) {
         ret = (*func)(&res, arg);
         if (ret)
             break;
 
         start = res.end + 1;
     }
 
     return ret;
 }
 
 /**
  * walk_iomem_res_desc - Walks through iomem resources and calls func()
  *           with matching resource ranges.
  * *
  * @desc: I/O resource descriptor. Use IORES_DESC_NONE to skip @desc check.
  * @flags: I/O resource flags
  * @start: start addr
  * @end: end addr
  * @arg: function argument for the callback @func
  * @func: callback function that is called for each qualifying resource area
  *
  * All the memory ranges which overlap start,end and also match flags and
  * desc are valid candidates.
  *
  * NOTE: For a new descriptor search, define a new IORES_DESC in
  * <linux/ioport.h> and set it in 'desc' of a target resource entry.
  */
 int walk_iomem_res_desc(unsigned long desc, unsigned long flags, u64 start,
         u64 end, void *arg, int (*func)(struct resource *, void *))
 {
     return __walk_iomem_res_desc(start, end, flags, desc, arg, func);
 }
 EXPORT_SYMBOL_GPL(walk_iomem_res_desc);
 
 /*
  * This function calls the @func callback against all memory ranges of type
  * System RAM which are marked as IORESOURCE_SYSTEM_RAM and IORESOUCE_BUSY.
  * Now, this function is only for System RAM, it deals with full ranges and
  * not PFNs. If resources are not PFN-aligned, dealing with PFNs can truncate
  * ranges.
  */
 int walk_system_ram_res(u64 start, u64 end, void *arg,
             int (*func)(struct resource *, void *))
 {
     unsigned long flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
 
     return __walk_iomem_res_desc(start, end, flags, IORES_DESC_NONE, arg,
                      func);
 }
 
 /*
  * This function calls the @func callback against all memory ranges, which
  * are ranges marked as IORESOURCE_MEM and IORESOUCE_BUSY.
  */
 int walk_mem_res(u64 start, u64 end, void *arg,
          int (*func)(struct resource *, void *))
 {
     unsigned long flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 
     return __walk_iomem_res_desc(start, end, flags, IORES_DESC_NONE, arg,
                      func);
 }
 
 /*
  * This function calls the @func callback against all memory ranges of type
  * System RAM which are marked as IORESOURCE_SYSTEM_RAM and IORESOUCE_BUSY.
  * It is to be used only for System RAM.
  */
 int walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
               void *arg, int (*func)(unsigned long, unsigned long, void *))
 {
     resource_size_t start, end;
     unsigned long flags;
     struct resource res;
     unsigned long pfn, end_pfn;
     int ret = -EINVAL;
 
     start = (u64) start_pfn << PAGE_SHIFT;
     end = ((u64)(start_pfn + nr_pages) << PAGE_SHIFT) - 1;
     flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
     while (start < end &&
            !find_next_iomem_res(start, end, flags, IORES_DESC_NONE, &res)) {
         pfn = PFN_UP(res.start);
         end_pfn = PFN_DOWN(res.end + 1);
         if (end_pfn > pfn)
             ret = (*func)(pfn, end_pfn - pfn, arg);
         if (ret)
             break;
         start = res.end + 1;
     }
     return ret;
 }
 
 static int __is_ram(unsigned long pfn, unsigned long nr_pages, void *arg)
 {
     return 1;
 }
 
 /*
  * This generic page_is_ram() returns true if specified address is
  * registered as System RAM in iomem_resource list.
  */
 int __weak page_is_ram(unsigned long pfn)
 {
     return walk_system_ram_range(pfn, 1, NULL, __is_ram) == 1;
 }
 EXPORT_SYMBOL_GPL(page_is_ram);
 
 static int __region_intersects(struct resource *parent, resource_size_t start,
                    size_t size, unsigned long flags,
                    unsigned long desc)
 {
     struct resource res;
     int type = 0; int other = 0;
     struct resource *p;
 
     res.start = start;
     res.end = start + size - 1;
 
     for (p = parent->child; p ; p = p->sibling) {
         bool is_type = (((p->flags & flags) == flags) &&
                 ((desc == IORES_DESC_NONE) ||
                  (desc == p->desc)));
 
         if (resource_overlaps(p, &res))
             is_type ? type++ : other++;
     }
 
     if (type == 0)
         return REGION_DISJOINT;
 
     if (other == 0)
         return REGION_INTERSECTS;
 
     return REGION_MIXED;
 }
 
 /**
  * region_intersects() - determine intersection of region with known resources
  * @start: region start address
  * @size: size of region
  * @flags: flags of resource (in iomem_resource)
  * @desc: descriptor of resource (in iomem_resource) or IORES_DESC_NONE
  *
  * Check if the specified region partially overlaps or fully eclipses a
  * resource identified by @flags and @desc (optional with IORES_DESC_NONE).
  * Return REGION_DISJOINT if the region does not overlap @flags/@desc,
  * return REGION_MIXED if the region overlaps @flags/@desc and another
  * resource, and return REGION_INTERSECTS if the region overlaps @flags/@desc
  * and no other defined resource. Note that REGION_INTERSECTS is also
  * returned in the case when the specified region overlaps RAM and undefined
  * memory holes.
  *
  * region_intersect() is used by memory remapping functions to ensure
  * the user is not remapping RAM and is a vast speed up over walking
  * through the resource table page by page.
  */
 int region_intersects(resource_size_t start, size_t size, unsigned long flags,
               unsigned long desc)
 {
     int ret;
 
     read_lock(&resource_lock);
     ret = __region_intersects(&iomem_resource, start, size, flags, desc);
     read_unlock(&resource_lock);
 
     return ret;
 }
 EXPORT_SYMBOL_GPL(region_intersects);
 
 void __weak arch_remove_reservations(struct resource *avail)
 {
 }
 
 static resource_size_t simple_align_resource(void *data,
                          const struct resource *avail,
                          resource_size_t size,
                          resource_size_t align)
 {
     return avail->start;
 }
 
 static void resource_clip(struct resource *res, resource_size_t min,
               resource_size_t max)
 {
     if (res->start < min)
         res->start = min;
     if (res->end > max)
         res->end = max;
 }
 
 /*
  * Find empty slot in the resource tree with the given range and
  * alignment constraints
  */
 static int __find_resource(struct resource *root, struct resource *old,
              struct resource *new,
              resource_size_t  size,
              struct resource_constraint *constraint)
 {
     struct resource *this = root->child;
     struct resource tmp = *new, avail, alloc;
 
     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.
      */
     if (this && this->start == root->start) {
         tmp.start = (this == old) ? old->start : this->end + 1;
         this = this->sibling;
     }
     for(;;) {
         if (this)
             tmp.end = (this == old) ?  this->end : this->start - 1;
         else
             tmp.end = root->end;
 
         if (tmp.end < tmp.start)
             goto next;
 
         resource_clip(&tmp, constraint->min, constraint->max);
         arch_remove_reservations(&tmp);
 
         /* Check for overflow after ALIGN() */
         avail.start = ALIGN(tmp.start, constraint->align);
         avail.end = tmp.end;
         avail.flags = new->flags & ~IORESOURCE_UNSET;
         if (avail.start >= tmp.start) {
             alloc.flags = avail.flags;
             alloc.start = constraint->alignf(constraint->alignf_data, &avail,
                     size, constraint->align);
             alloc.end = alloc.start + size - 1;
             if (alloc.start <= alloc.end &&
                 resource_contains(&avail, &alloc)) {
                 new->start = alloc.start;
                 new->end = alloc.end;
                 return 0;
             }
         }
 
 next:       if (!this || this->end == root->end)
             break;
 
         if (this != old)
             tmp.start = this->end + 1;
         this = this->sibling;
     }
     return -EBUSY;
 }
 
 /*
  * Find empty slot in the resource tree given range and alignment.
  */
 static int find_resource(struct resource *root, struct resource *new,
             resource_size_t size,
             struct resource_constraint  *constraint)
 {
     return  __find_resource(root, NULL, new, size, constraint);
 }
 
 /**
  * reallocate_resource - allocate a slot in the resource tree given range & alignment.
  *  The resource will be relocated if the new size cannot be reallocated in the
  *  current location.
  *
  * @root: root resource descriptor
  * @old:  resource descriptor desired by caller
  * @newsize: new size of the resource descriptor
  * @constraint: the size and alignment constraints to be met.
  */
 static int reallocate_resource(struct resource *root, struct resource *old,
                    resource_size_t newsize,
                    struct resource_constraint *constraint)
 {
     int err=0;
     struct resource new = *old;
     struct resource *conflict;
 
     write_lock(&resource_lock);
 
     if ((err = __find_resource(root, old, &new, newsize, constraint)))
         goto out;
 
     if (resource_contains(&new, old)) {
         old->start = new.start;
         old->end = new.end;
         goto out;
     }
 
     if (old->child) {
         err = -EBUSY;
         goto out;
     }
 
     if (resource_contains(old, &new)) {
         old->start = new.start;
         old->end = new.end;
     } else {
         __release_resource(old, true);
         *old = new;
         conflict = __request_resource(root, old);
         BUG_ON(conflict);
     }
 out:
     write_unlock(&resource_lock);
     return err;
 }
 
 
 /**
  * allocate_resource - allocate empty slot in the resource tree given range & alignment.
  *  The resource will be reallocated with a new size if it was already allocated
  * @root: root resource descriptor
  * @new: resource descriptor desired by caller
  * @size: requested resource region size
  * @min: minimum boundary to allocate
  * @max: maximum boundary to allocate
  * @align: alignment requested, in bytes
  * @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,
               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)
 {
     int err;
     struct resource_constraint constraint;
 
     if (!alignf)
         alignf = simple_align_resource;
 
     constraint.min = min;
     constraint.max = max;
     constraint.align = align;
     constraint.alignf = alignf;
     constraint.alignf_data = alignf_data;
 
     if ( new->parent ) {
         /* resource is already allocated, try reallocating with
            the new constraints */
         return reallocate_resource(root, new, size, &constraint);
     }
 
     write_lock(&resource_lock);
     err = find_resource(root, new, size, &constraint);
     if (err >= 0 && __request_resource(root, new))
         err = -EBUSY;
     write_unlock(&resource_lock);
     return err;
 }
 
 EXPORT_SYMBOL(allocate_resource);
 
 /**
  * lookup_resource - find an existing resource by a resource start address
  * @root: root resource descriptor
  * @start: resource start address
  *
  * Returns a pointer to the resource if found, NULL otherwise
  */
 struct resource *lookup_resource(struct resource *root, resource_size_t start)
 {
     struct resource *res;
 
     read_lock(&resource_lock);
     for (res = root->child; res; res = res->sibling) {
         if (res->start == start)
             break;
     }
     read_unlock(&resource_lock);
 
     return res;
 }
 
 /*
  * Insert a resource into the resource tree. If successful, return NULL,
  * otherwise return the conflicting resource (compare to __request_resource())
  */
 static struct resource * __insert_resource(struct resource *parent, struct resource *new)
 {
     struct resource *first, *next;
 
     for (;; parent = first) {
         first = __request_resource(parent, new);
         if (!first)
             return first;
 
         if (first == parent)
             return first;
         if (WARN_ON(first == new))  /* duplicated insertion */
             return first;
 
         if ((first->start > new->start) || (first->end < new->end))
             break;
         if ((first->start == new->start) && (first->end == new->end))
             break;
     }
 
     for (next = first; ; next = next->sibling) {
         /* Partial overlap? Bad, and unfixable */
         if (next->start < new->start || next->end > new->end)
             return next;
         if (!next->sibling)
             break;
         if (next->sibling->start > new->end)
             break;
     }
 
     new->parent = parent;
     new->sibling = next->sibling;
     new->child = first;
 
     next->sibling = NULL;
     for (next = first; next; next = next->sibling)
         next->parent = new;
 
     if (parent->child == first) {
         parent->child = new;
     } else {
         next = parent->child;
         while (next->sibling != first)
             next = next->sibling;
         next->sibling = new;
     }
     return NULL;
 }
 
 /**
  * insert_resource_conflict - Inserts resource in the resource tree
  * @parent: parent of the new resource
  * @new: new resource to insert
  *
  * Returns 0 on success, conflict resource if the resource can't be inserted.
  *
  * This function is equivalent to request_resource_conflict when no conflict
  * happens. If a conflict happens, and the conflicting resources
  * entirely fit within the range of the new resource, then the new
  * resource is inserted and the conflicting resources become children of
  * the new resource.
  *
  * This function is intended for producers of resources, such as FW modules
  * and bus drivers.
  */
 struct resource *insert_resource_conflict(struct resource *parent, struct resource *new)
 {
     struct resource *conflict;
 
     write_lock(&resource_lock);
     conflict = __insert_resource(parent, new);
     write_unlock(&resource_lock);
     return conflict;
 }
 
 /**
  * insert_resource - Inserts a resource in the resource tree
  * @parent: parent of the new resource
  * @new: new resource to insert
  *
  * Returns 0 on success, -EBUSY if the resource can't be inserted.
  *
  * This function is intended for producers of resources, such as FW modules
  * and bus drivers.
  */
 int insert_resource(struct resource *parent, struct resource *new)
 {
     struct resource *conflict;
 
     conflict = insert_resource_conflict(parent, new);
     return conflict ? -EBUSY : 0;
 }
 EXPORT_SYMBOL_GPL(insert_resource);
 
 /**
  * insert_resource_expand_to_fit - Insert a resource into the resource tree
  * @root: root resource descriptor
  * @new: new resource to insert
  *
  * Insert a resource into the resource tree, possibly expanding it in order
  * to make it encompass any conflicting resources.
  */
 void insert_resource_expand_to_fit(struct resource *root, struct resource *new)
 {
     if (new->parent)
         return;
 
     write_lock(&resource_lock);
     for (;;) {
         struct resource *conflict;
 
         conflict = __insert_resource(root, new);
         if (!conflict)
             break;
         if (conflict == root)
             break;
 
         /* Ok, expand resource to cover the conflict, then try again .. */
         if (conflict->start < new->start)
             new->start = conflict->start;
         if (conflict->end > new->end)
             new->end = conflict->end;
 
         printk("Expanded resource %s due to conflict with %s\n", new->name, conflict->name);
     }
     write_unlock(&resource_lock);
 }
 /*
  * Not for general consumption, only early boot memory map parsing, PCI
  * resource discovery, and late discovery of CXL resources are expected
  * to use this interface. The former are built-in and only the latter,
  * CXL, is a module.
  */
 EXPORT_SYMBOL_NS_GPL(insert_resource_expand_to_fit, CXL);
 
 /**
  * remove_resource - Remove a resource in the resource tree
  * @old: resource to remove
  *
  * Returns 0 on success, -EINVAL if the resource is not valid.
  *
  * This function removes a resource previously inserted by insert_resource()
  * or insert_resource_conflict(), and moves the children (if any) up to
  * where they were before.  insert_resource() and insert_resource_conflict()
  * insert a new resource, and move any conflicting resources down to the
  * children of the new resource.
  *
  * insert_resource(), insert_resource_conflict() and remove_resource() are
  * intended for producers of resources, such as FW modules and bus drivers.
  */
 int remove_resource(struct resource *old)
 {
     int retval;
 
     write_lock(&resource_lock);
     retval = __release_resource(old, false);
     write_unlock(&resource_lock);
     return retval;
 }
 EXPORT_SYMBOL_GPL(remove_resource);
 
 static int __adjust_resource(struct resource *res, resource_size_t start,
                 resource_size_t size)
 {
     struct resource *tmp, *parent = res->parent;
     resource_size_t end = start + size - 1;
     int result = -EBUSY;
 
     if (!parent)
         goto skip;
 
     if ((start < parent->start) || (end > parent->end))
         goto out;
 
     if (res->sibling && (res->sibling->start <= end))
         goto out;
 
     tmp = parent->child;
     if (tmp != res) {
         while (tmp->sibling != res)
             tmp = tmp->sibling;
         if (start <= tmp->end)
             goto out;
     }
 
 skip:
     for (tmp = res->child; tmp; tmp = tmp->sibling)
         if ((tmp->start < start) || (tmp->end > end))
             goto out;
 
     res->start = start;
     res->end = end;
     result = 0;
 
  out:
     return result;
 }
 
 /**
  * adjust_resource - modify a resource's start and size
  * @res: resource to modify
  * @start: new start value
  * @size: new size
  *
  * Given an existing resource, change its start and size to match the
  * arguments.  Returns 0 on success, -EBUSY if it can't fit.
  * Existing children of the resource are assumed to be immutable.
  */
 int adjust_resource(struct resource *res, resource_size_t start,
             resource_size_t size)
 {
     int result;
 
     write_lock(&resource_lock);
     result = __adjust_resource(res, start, size);
     write_unlock(&resource_lock);
     return result;
 }
 EXPORT_SYMBOL(adjust_resource);
 
 static void __init
 __reserve_region_with_split(struct resource *root, resource_size_t start,
                 resource_size_t end, const char *name)
 {
     struct resource *parent = root;
     struct resource *conflict;
     struct resource *res = alloc_resource(GFP_ATOMIC);
     struct resource *next_res = NULL;
     int type = resource_type(root);
 
     if (!res)
         return;
 
     res->name = name;
     res->start = start;
     res->end = end;
     res->flags = type | IORESOURCE_BUSY;
     res->desc = IORES_DESC_NONE;
 
     while (1) {
 
         conflict = __request_resource(parent, res);
         if (!conflict) {
             if (!next_res)
                 break;
             res = next_res;
             next_res = NULL;
             continue;
         }
 
         /* conflict covered whole area */
         if (conflict->start <= res->start &&
                 conflict->end >= res->end) {
             free_resource(res);
             WARN_ON(next_res);
             break;
         }
 
         /* failed, split and try again */
         if (conflict->start > res->start) {
             end = res->end;
             res->end = conflict->start - 1;
             if (conflict->end < end) {
                 next_res = alloc_resource(GFP_ATOMIC);
                 if (!next_res) {
                     free_resource(res);
                     break;
                 }
                 next_res->name = name;
                 next_res->start = conflict->end + 1;
                 next_res->end = end;
                 next_res->flags = type | IORESOURCE_BUSY;
                 next_res->desc = IORES_DESC_NONE;
             }
         } else {
             res->start = conflict->end + 1;
         }
     }
 
 }
 
 void __init
 reserve_region_with_split(struct resource *root, resource_size_t start,
               resource_size_t end, const char *name)
 {
     int abort = 0;
 
     write_lock(&resource_lock);
     if (root->start > start || root->end < end) {
         pr_err("requested range [0x%llx-0x%llx] not in root %pr\n",
                (unsigned long long)start, (unsigned long long)end,
                root);
         if (start > root->end || end < root->start)
             abort = 1;
         else {
             if (end > root->end)
                 end = root->end;
             if (start < root->start)
                 start = root->start;
             pr_err("fixing request to [0x%llx-0x%llx]\n",
                    (unsigned long long)start,
                    (unsigned long long)end);
         }
         dump_stack();
     }
     if (!abort)
         __reserve_region_with_split(root, start, end, name);
     write_unlock(&resource_lock);
 }
 
 /**
  * resource_alignment - calculate resource's alignment
  * @res: resource pointer
  *
  * Returns alignment on success, 0 (invalid alignment) on failure.
  */
 resource_size_t resource_alignment(struct resource *res)
 {
     switch (res->flags & (IORESOURCE_SIZEALIGN | IORESOURCE_STARTALIGN)) {
     case IORESOURCE_SIZEALIGN:
         return resource_size(res);
     case IORESOURCE_STARTALIGN:
         return res->start;
     default:
         return 0;
     }
 }
 
 /*
  * This is compatibility stuff for IO resources.
  *
  * Note how this, unlike the above, knows about
  * the IO flag meanings (busy etc).
  *
  * request_region creates a new busy region.
  *
  * release_region releases a matching busy region.
  */
 
 static DECLARE_WAIT_QUEUE_HEAD(muxed_resource_wait);
 
 static struct inode *iomem_inode;
 
 #ifdef CONFIG_IO_STRICT_DEVMEM
 static void revoke_iomem(struct resource *res)
 {
     /* pairs with smp_store_release() in iomem_init_inode() */
     struct inode *inode = smp_load_acquire(&iomem_inode);
 
     /*
      * Check that the initialization has completed. Losing the race
      * is ok because it means drivers are claiming resources before
      * the fs_initcall level of init and prevent iomem_get_mapping users
      * from establishing mappings.
      */
     if (!inode)
         return;
 
     /*
      * The expectation is that the driver has successfully marked
      * the resource busy by this point, so devmem_is_allowed()
      * should start returning false, however for performance this
      * does not iterate the entire resource range.
      */
     if (devmem_is_allowed(PHYS_PFN(res->start)) &&
         devmem_is_allowed(PHYS_PFN(res->end))) {
         /*
          * *cringe* iomem=relaxed says "go ahead, what's the
          * worst that can happen?"
          */
         return;
     }
 
     unmap_mapping_range(inode->i_mapping, res->start, resource_size(res), 1);
 }
 #else
 static void revoke_iomem(struct resource *res) {}
 #endif
 
 struct address_space *iomem_get_mapping(void)
 {
     /*
      * This function is only called from file open paths, hence guaranteed
      * that fs_initcalls have completed and no need to check for NULL. But
      * since revoke_iomem can be called before the initcall we still need
      * the barrier to appease checkers.
      */
     return smp_load_acquire(&iomem_inode)->i_mapping;
 }
 
 static int __request_region_locked(struct resource *res, struct resource *parent,
                    resource_size_t start, resource_size_t n,
                    const char *name, int flags)
 {
     DECLARE_WAITQUEUE(wait, current);
 
     res->name = name;
     res->start = start;
     res->end = start + n - 1;
 
     for (;;) {
         struct resource *conflict;
 
         res->flags = resource_type(parent) | resource_ext_type(parent);
         res->flags |= IORESOURCE_BUSY | flags;
         res->desc = parent->desc;
 
         conflict = __request_resource(parent, res);
         if (!conflict)
             break;
         /*
          * mm/hmm.c reserves physical addresses which then
          * become unavailable to other users.  Conflicts are
          * not expected.  Warn to aid debugging if encountered.
          */
         if (conflict->desc == IORES_DESC_DEVICE_PRIVATE_MEMORY) {
             pr_warn("Unaddressable device %s %pR conflicts with %pR",
                 conflict->name, conflict, res);
         }
         if (conflict != parent) {
             if (!(conflict->flags & IORESOURCE_BUSY)) {
                 parent = conflict;
                 continue;
             }
         }
         if (conflict->flags & flags & IORESOURCE_MUXED) {
             add_wait_queue(&muxed_resource_wait, &wait);
             write_unlock(&resource_lock);
             set_current_state(TASK_UNINTERRUPTIBLE);
             schedule();
             remove_wait_queue(&muxed_resource_wait, &wait);
             write_lock(&resource_lock);
             continue;
         }
         /* Uhhuh, that didn't work out.. */
         return -EBUSY;
     }
 
     return 0;
 }
 
 /**
  * __request_region - create a new busy resource region
  * @parent: parent resource descriptor
  * @start: resource start address
  * @n: resource region size
  * @name: reserving caller's ID string
  * @flags: IO resource flags
  */
 struct resource *__request_region(struct resource *parent,
                   resource_size_t start, resource_size_t n,
                   const char *name, int flags)
 {
     struct resource *res = alloc_resource(GFP_KERNEL);
     int ret;
 
     if (!res)
         return NULL;
 
     write_lock(&resource_lock);
     ret = __request_region_locked(res, parent, start, n, name, flags);
     write_unlock(&resource_lock);
 
     if (ret) {
         free_resource(res);
         return NULL;
     }
 
     if (parent == &iomem_resource)
         revoke_iomem(res);
 
     return res;
 }
 EXPORT_SYMBOL(__request_region);
 
 /**
  * __release_region - release a previously reserved resource region
  * @parent: parent resource descriptor
  * @start: resource start address
  * @n: resource region size
  *
  * The described resource region must match a currently busy region.
  */
 void __release_region(struct resource *parent, resource_size_t start,
               resource_size_t n)
 {
     struct resource **p;
     resource_size_t end;
 
     p = &parent->child;
     end = start + n - 1;
 
     write_lock(&resource_lock);
 
     for (;;) {
         struct resource *res = *p;
 
         if (!res)
             break;
         if (res->start <= start && res->end >= end) {
             if (!(res->flags & IORESOURCE_BUSY)) {
                 p = &res->child;
                 continue;
             }
             if (res->start != start || res->end != end)
                 break;
             *p = res->sibling;
             write_unlock(&resource_lock);
             if (res->flags & IORESOURCE_MUXED)
                 wake_up(&muxed_resource_wait);
             free_resource(res);
             return;
         }
         p = &res->sibling;
     }
 
     write_unlock(&resource_lock);
 
     printk(KERN_WARNING "Trying to free nonexistent resource "
         "<%016llx-%016llx>\n", (unsigned long long)start,
         (unsigned long long)end);
 }
 EXPORT_SYMBOL(__release_region);
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
 /**
  * release_mem_region_adjustable - release a previously reserved memory region
  * @start: resource start address
  * @size: resource region size
  *
  * This interface is intended for memory hot-delete.  The requested region
  * is released from a currently busy memory resource.  The requested region
  * must either match exactly or fit into a single busy resource entry.  In
  * the latter case, the remaining resource is adjusted accordingly.
  * Existing children of the busy memory resource must be immutable in the
  * request.
  *
  * Note:
  * - Additional release conditions, such as overlapping region, can be
  *   supported after they are confirmed as valid cases.
  * - When a busy memory resource gets split into two entries, the code
  *   assumes that all children remain in the lower address entry for
  *   simplicity.  Enhance this logic when necessary.
  */
 void release_mem_region_adjustable(resource_size_t start, resource_size_t size)
 {
     struct resource *parent = &iomem_resource;
     struct resource *new_res = NULL;
     bool alloc_nofail = false;
     struct resource **p;
     struct resource *res;
     resource_size_t end;
 
     end = start + size - 1;
     if (WARN_ON_ONCE((start < parent->start) || (end > parent->end)))
         return;
 
     /*
      * We free up quite a lot of memory on memory hotunplug (esp., memap),
      * just before releasing the region. This is highly unlikely to
      * fail - let's play save and make it never fail as the caller cannot
      * perform any error handling (e.g., trying to re-add memory will fail
      * similarly).
      */
 retry:
     new_res = alloc_resource(GFP_KERNEL | (alloc_nofail ? __GFP_NOFAIL : 0));
 
     p = &parent->child;
     write_lock(&resource_lock);
 
     while ((res = *p)) {
         if (res->start >= end)
             break;
 
         /* look for the next resource if it does not fit into */
         if (res->start > start || res->end < end) {
             p = &res->sibling;
             continue;
         }
 
         /*
          * All memory regions added from memory-hotplug path have the
          * flag IORESOURCE_SYSTEM_RAM. If the resource does not have
          * this flag, we know that we are dealing with a resource coming
          * from HMM/devm. HMM/devm use another mechanism to add/release
          * a resource. This goes via devm_request_mem_region and
          * devm_release_mem_region.
          * HMM/devm take care to release their resources when they want,
          * so if we are dealing with them, let us just back off here.
          */
         if (!(res->flags & IORESOURCE_SYSRAM)) {
             break;
         }
 
         if (!(res->flags & IORESOURCE_MEM))
             break;
 
         if (!(res->flags & IORESOURCE_BUSY)) {
             p = &res->child;
             continue;
         }
 
         /* found the target resource; let's adjust accordingly */
         if (res->start == start && res->end == end) {
             /* free the whole entry */
             *p = res->sibling;
             free_resource(res);
         } else if (res->start == start && res->end != end) {
             /* adjust the start */
             WARN_ON_ONCE(__adjust_resource(res, end + 1,
                                res->end - end));
         } else if (res->start != start && res->end == end) {
             /* adjust the end */
             WARN_ON_ONCE(__adjust_resource(res, res->start,
                                start - res->start));
         } else {
             /* split into two entries - we need a new resource */
             if (!new_res) {
                 new_res = alloc_resource(GFP_ATOMIC);
                 if (!new_res) {
                     alloc_nofail = true;
                     write_unlock(&resource_lock);
                     goto retry;
                 }
             }
             new_res->name = res->name;
             new_res->start = end + 1;
             new_res->end = res->end;
             new_res->flags = res->flags;
             new_res->desc = res->desc;
             new_res->parent = res->parent;
             new_res->sibling = res->sibling;
             new_res->child = NULL;
 
             if (WARN_ON_ONCE(__adjust_resource(res, res->start,
                                start - res->start)))
                 break;
             res->sibling = new_res;
             new_res = NULL;
         }
 
         break;
     }
 
     write_unlock(&resource_lock);
     free_resource(new_res);
 }
 #endif  /* CONFIG_MEMORY_HOTREMOVE */
 
 #ifdef CONFIG_MEMORY_HOTPLUG
 static bool system_ram_resources_mergeable(struct resource *r1,
                        struct resource *r2)
 {
     /* We assume either r1 or r2 is IORESOURCE_SYSRAM_MERGEABLE. */
     return r1->flags == r2->flags && r1->end + 1 == r2->start &&
            r1->name == r2->name && r1->desc == r2->desc &&
            !r1->child && !r2->child;
 }
 
 /**
  * merge_system_ram_resource - mark the System RAM resource mergeable and try to
  *  merge it with adjacent, mergeable resources
  * @res: resource descriptor
  *
  * This interface is intended for memory hotplug, whereby lots of contiguous
  * system ram resources are added (e.g., via add_memory*()) by a driver, and
  * the actual resource boundaries are not of interest (e.g., it might be
  * relevant for DIMMs). Only resources that are marked mergeable, that have the
  * same parent, and that don't have any children are considered. All mergeable
  * resources must be immutable during the request.
  *
  * Note:
  * - The caller has to make sure that no pointers to resources that are
  *   marked mergeable are used anymore after this call - the resource might
  *   be freed and the pointer might be stale!
  * - release_mem_region_adjustable() will split on demand on memory hotunplug
  */
 void merge_system_ram_resource(struct resource *res)
 {
     const unsigned long flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
     struct resource *cur;
 
     if (WARN_ON_ONCE((res->flags & flags) != flags))
         return;
 
     write_lock(&resource_lock);
     res->flags |= IORESOURCE_SYSRAM_MERGEABLE;
 
     /* Try to merge with next item in the list. */
     cur = res->sibling;
     if (cur && system_ram_resources_mergeable(res, cur)) {
         res->end = cur->end;
         res->sibling = cur->sibling;
         free_resource(cur);
     }
 
     /* Try to merge with previous item in the list. */
     cur = res->parent->child;
     while (cur && cur->sibling != res)
         cur = cur->sibling;
     if (cur && system_ram_resources_mergeable(cur, res)) {
         cur->end = res->end;
         cur->sibling = res->sibling;
         free_resource(res);
     }
     write_unlock(&resource_lock);
 }
 #endif  /* CONFIG_MEMORY_HOTPLUG */
 
 /*
  * Managed region resource
  */
 static void devm_resource_release(struct device *dev, void *ptr)
 {
     struct resource **r = ptr;
 
     release_resource(*r);
 }
 
 /**
  * devm_request_resource() - request and reserve an I/O or memory resource
  * @dev: device for which to request the resource
  * @root: root of the resource tree from which to request the resource
  * @new: descriptor of the resource to request
  *
  * This is a device-managed version of request_resource(). There is usually
  * no need to release resources requested by this function explicitly since
  * that will be taken care of when the device is unbound from its driver.
  * If for some reason the resource needs to be released explicitly, because
  * of ordering issues for example, drivers must call devm_release_resource()
  * rather than the regular release_resource().
  *
  * When a conflict is detected between any existing resources and the newly
  * requested resource, an error message will be printed.
  *
  * Returns 0 on success or a negative error code on failure.
  */
 int devm_request_resource(struct device *dev, struct resource *root,
               struct resource *new)
 {
     struct resource *conflict, **ptr;
 
     ptr = devres_alloc(devm_resource_release, sizeof(*ptr), GFP_KERNEL);
     if (!ptr)
         return -ENOMEM;
 
     *ptr = new;
 
     conflict = request_resource_conflict(root, new);
     if (conflict) {
         dev_err(dev, "resource collision: %pR conflicts with %s %pR\n",
             new, conflict->name, conflict);
         devres_free(ptr);
         return -EBUSY;
     }
 
     devres_add(dev, ptr);
     return 0;
 }
 EXPORT_SYMBOL(devm_request_resource);
 
 static int devm_resource_match(struct device *dev, void *res, void *data)
 {
     struct resource **ptr = res;
 
     return *ptr == data;
 }
 
 /**
  * devm_release_resource() - release a previously requested resource
  * @dev: device for which to release the resource
  * @new: descriptor of the resource to release
  *
  * Releases a resource previously requested using devm_request_resource().
  */
 void devm_release_resource(struct device *dev, struct resource *new)
 {
     WARN_ON(devres_release(dev, devm_resource_release, devm_resource_match,
                    new));
 }
 EXPORT_SYMBOL(devm_release_resource);
 
 struct region_devres {
     struct resource *parent;
     resource_size_t start;
     resource_size_t n;
 };
 
 static void devm_region_release(struct device *dev, void *res)
 {
     struct region_devres *this = res;
 
     __release_region(this->parent, this->start, this->n);
 }
 
 static int devm_region_match(struct device *dev, void *res, void *match_data)
 {
     struct region_devres *this = res, *match = match_data;
 
     return this->parent == match->parent &&
         this->start == match->start && this->n == match->n;
 }
 
 struct resource *
 __devm_request_region(struct device *dev, struct resource *parent,
               resource_size_t start, resource_size_t n, const char *name)
 {
     struct region_devres *dr = NULL;
     struct resource *res;
 
     dr = devres_alloc(devm_region_release, sizeof(struct region_devres),
               GFP_KERNEL);
     if (!dr)
         return NULL;
 
     dr->parent = parent;
     dr->start = start;
     dr->n = n;
 
     res = __request_region(parent, start, n, name, 0);
     if (res)
         devres_add(dev, dr);
     else
         devres_free(dr);
 
     return res;
 }
 EXPORT_SYMBOL(__devm_request_region);
 
 void __devm_release_region(struct device *dev, struct resource *parent,
                resource_size_t start, resource_size_t n)
 {
     struct region_devres match_data = { parent, start, n };
 
     __release_region(parent, start, n);
     WARN_ON(devres_destroy(dev, devm_region_release, devm_region_match,
                    &match_data));
 }
 EXPORT_SYMBOL(__devm_release_region);
 
 /*
  * Reserve I/O ports or memory based on "reserve=" kernel parameter.
  */
 #define MAXRESERVE 4
 static int __init reserve_setup(char *str)
 {
     static int reserved;
     static struct resource reserve[MAXRESERVE];
 
     for (;;) {
         unsigned int io_start, io_num;
         int x = reserved;
         struct resource *parent;
 
         if (get_option(&str, &io_start) != 2)
             break;
         if (get_option(&str, &io_num) == 0)
             break;
         if (x < MAXRESERVE) {
             struct resource *res = reserve + x;
 
             /*
              * If the region starts below 0x10000, we assume it's
              * I/O port space; otherwise assume it's memory.
              */
             if (io_start < 0x10000) {
                 res->flags = IORESOURCE_IO;
                 parent = &ioport_resource;
             } else {
                 res->flags = IORESOURCE_MEM;
                 parent = &iomem_resource;
             }
             res->name = "reserved";
             res->start = io_start;
             res->end = io_start + io_num - 1;
             res->flags |= IORESOURCE_BUSY;
             res->desc = IORES_DESC_NONE;
             res->child = NULL;
             if (request_resource(parent, res) == 0)
                 reserved = x+1;
         }
     }
     return 1;
 }
 __setup("reserve=", reserve_setup);
 
 /*
  * Check if the requested addr and size spans more than any slot in the
  * iomem resource tree.
  */
 int iomem_map_sanity_check(resource_size_t addr, unsigned long size)
 {
     struct resource *p = &iomem_resource;
     int err = 0;
     loff_t l;
 
     read_lock(&resource_lock);
     for (p = p->child; p ; p = r_next(NULL, p, &l)) {
         /*
          * We can probably skip the resources without
          * IORESOURCE_IO attribute?
          */
         if (p->start >= addr + size)
             continue;
         if (p->end < addr)
             continue;
         if (PFN_DOWN(p->start) <= PFN_DOWN(addr) &&
             PFN_DOWN(p->end) >= PFN_DOWN(addr + size - 1))
             continue;
         /*
          * if a resource is "BUSY", it's not a hardware resource
          * but a driver mapping of such a resource; we don't want
          * to warn for those; some drivers legitimately map only
          * partial hardware resources. (example: vesafb)
          */
         if (p->flags & IORESOURCE_BUSY)
             continue;
 
         printk(KERN_WARNING "resource sanity check: requesting [mem %#010llx-%#010llx], which spans more than %s %pR\n",
                (unsigned long long)addr,
                (unsigned long long)(addr + size - 1),
                p->name, p);
         err = -1;
         break;
     }
     read_unlock(&resource_lock);
 
     return err;
 }
 
 #ifdef CONFIG_STRICT_DEVMEM
 static int strict_iomem_checks = 1;
 #else
 static int strict_iomem_checks;
 #endif
 
 /*
  * Check if an address is exclusive to the kernel and must not be mapped to
  * user space, for example, via /dev/mem.
  *
  * Returns true if exclusive to the kernel, otherwise returns false.
  */
 bool iomem_is_exclusive(u64 addr)
 {
     const unsigned int exclusive_system_ram = IORESOURCE_SYSTEM_RAM |
                           IORESOURCE_EXCLUSIVE;
     bool skip_children = false, err = false;
     int size = PAGE_SIZE;
     struct resource *p;
 
     addr = addr & PAGE_MASK;
 
     read_lock(&resource_lock);
     for_each_resource(&iomem_resource, p, skip_children) {
         if (p->start >= addr + size)
             break;
         if (p->end < addr) {
             skip_children = true;
             continue;
         }
         skip_children = false;
 
         /*
          * IORESOURCE_SYSTEM_RAM resources are exclusive if
          * IORESOURCE_EXCLUSIVE is set, even if they
          * are not busy and even if "iomem=relaxed" is set. The
          * responsible driver dynamically adds/removes system RAM within
          * such an area and uncontrolled access is dangerous.
          */
         if ((p->flags & exclusive_system_ram) == exclusive_system_ram) {
             err = true;
             break;
         }
 
         /*
          * A resource is exclusive if IORESOURCE_EXCLUSIVE is set
          * or CONFIG_IO_STRICT_DEVMEM is enabled and the
          * resource is busy.
          */
         if (!strict_iomem_checks || !(p->flags & IORESOURCE_BUSY))
             continue;
         if (IS_ENABLED(CONFIG_IO_STRICT_DEVMEM)
                 || p->flags & IORESOURCE_EXCLUSIVE) {
             err = true;
             break;
         }
     }
     read_unlock(&resource_lock);
 
     return err;
 }
 
 struct resource_entry *resource_list_create_entry(struct resource *res,
                           size_t extra_size)
 {
     struct resource_entry *entry;
 
     entry = kzalloc(sizeof(*entry) + extra_size, GFP_KERNEL);
     if (entry) {
         INIT_LIST_HEAD(&entry->node);
         entry->res = res ? res : &entry->__res;
     }
 
     return entry;
 }
 EXPORT_SYMBOL(resource_list_create_entry);
 
 void resource_list_free(struct list_head *head)
 {
     struct resource_entry *entry, *tmp;
 
     list_for_each_entry_safe(entry, tmp, head, node)
         resource_list_destroy_entry(entry);
 }
 EXPORT_SYMBOL(resource_list_free);
 
 #ifdef CONFIG_GET_FREE_REGION
 #define GFR_DESCENDING      (1UL << 0)
 #define GFR_REQUEST_REGION  (1UL << 1)
 #define GFR_DEFAULT_ALIGN (1UL << PA_SECTION_SHIFT)
 
 static resource_size_t gfr_start(struct resource *base, resource_size_t size,
                  resource_size_t align, unsigned long flags)
 {
     if (flags & GFR_DESCENDING) {
         resource_size_t end;
 
         end = min_t(resource_size_t, base->end,
                 (1ULL << MAX_PHYSMEM_BITS) - 1);
         return end - size + 1;
     }
 
     return ALIGN(base->start, align);
 }
 
 static bool gfr_continue(struct resource *base, resource_size_t addr,
              resource_size_t size, unsigned long flags)
 {
     if (flags & GFR_DESCENDING)
         return addr > size && addr >= base->start;
     /*
      * In the ascend case be careful that the last increment by
      * @size did not wrap 0.
      */
     return addr > addr - size &&
            addr <= min_t(resource_size_t, base->end,
                  (1ULL << MAX_PHYSMEM_BITS) - 1);
 }
 
 static resource_size_t gfr_next(resource_size_t addr, resource_size_t size,
                 unsigned long flags)
 {
     if (flags & GFR_DESCENDING)
         return addr - size;
     return addr + size;
 }
 
 static void remove_free_mem_region(void *_res)
 {
     struct resource *res = _res;
 
     if (res->parent)
         remove_resource(res);
     free_resource(res);
 }
 
 static struct resource *
 get_free_mem_region(struct device *dev, struct resource *base,
             resource_size_t size, const unsigned long align,
             const char *name, const unsigned long desc,
             const unsigned long flags)
 {
     resource_size_t addr;
     struct resource *res;
     struct region_devres *dr = NULL;
 
     size = ALIGN(size, align);
 
     res = alloc_resource(GFP_KERNEL);
     if (!res)
         return ERR_PTR(-ENOMEM);
 
     if (dev && (flags & GFR_REQUEST_REGION)) {
         dr = devres_alloc(devm_region_release,
                 sizeof(struct region_devres), GFP_KERNEL);
         if (!dr) {
             free_resource(res);
             return ERR_PTR(-ENOMEM);
         }
     } else if (dev) {
         if (devm_add_action_or_reset(dev, remove_free_mem_region, res))
             return ERR_PTR(-ENOMEM);
     }
 
     write_lock(&resource_lock);
     for (addr = gfr_start(base, size, align, flags);
          gfr_continue(base, addr, size, flags);
          addr = gfr_next(addr, size, flags)) {
         if (__region_intersects(base, addr, size, 0, IORES_DESC_NONE) !=
             REGION_DISJOINT)
             continue;
 
         if (flags & GFR_REQUEST_REGION) {
             if (__request_region_locked(res, &iomem_resource, addr,
                             size, name, 0))
                 break;
 
             if (dev) {
                 dr->parent = &iomem_resource;
                 dr->start = addr;
                 dr->n = size;
                 devres_add(dev, dr);
             }
 
             res->desc = desc;
             write_unlock(&resource_lock);
 
 
             /*
              * A driver is claiming this region so revoke any
              * mappings.
              */
             revoke_iomem(res);
         } else {
             res->start = addr;
             res->end = addr + size - 1;
             res->name = name;
             res->desc = desc;
             res->flags = IORESOURCE_MEM;
 
             /*
              * Only succeed if the resource hosts an exclusive
              * range after the insert
              */
             if (__insert_resource(base, res) || res->child)
                 break;
 
             write_unlock(&resource_lock);
         }
 
         return res;
     }
     write_unlock(&resource_lock);
 
     if (flags & GFR_REQUEST_REGION) {
         free_resource(res);
         devres_free(dr);
     } else if (dev)
         devm_release_action(dev, remove_free_mem_region, res);
 
     return ERR_PTR(-ERANGE);
 }
 
 /**
  * devm_request_free_mem_region - find free region for device private memory
  *
  * @dev: device struct to bind the resource to
  * @size: size in bytes of the device memory to add
  * @base: resource tree to look in
  *
  * This function tries to find an empty range of physical address big enough to
  * contain the new resource, so that it can later be hotplugged as ZONE_DEVICE
  * memory, which in turn allocates struct pages.
  */
 struct resource *devm_request_free_mem_region(struct device *dev,
         struct resource *base, unsigned long size)
 {
     unsigned long flags = GFR_DESCENDING | GFR_REQUEST_REGION;
 
     return get_free_mem_region(dev, base, size, GFR_DEFAULT_ALIGN,
                    dev_name(dev),
                    IORES_DESC_DEVICE_PRIVATE_MEMORY, flags);
 }
 EXPORT_SYMBOL_GPL(devm_request_free_mem_region);
 
 struct resource *request_free_mem_region(struct resource *base,
         unsigned long size, const char *name)
 {
     unsigned long flags = GFR_DESCENDING | GFR_REQUEST_REGION;
 
     return get_free_mem_region(NULL, base, size, GFR_DEFAULT_ALIGN, name,
                    IORES_DESC_DEVICE_PRIVATE_MEMORY, flags);
 }
 EXPORT_SYMBOL_GPL(request_free_mem_region);
 
 /**
  * alloc_free_mem_region - find a free region relative to @base
  * @base: resource that will parent the new resource
  * @size: size in bytes of memory to allocate from @base
  * @align: alignment requirements for the allocation
  * @name: resource name
  *
  * Buses like CXL, that can dynamically instantiate new memory regions,
  * need a method to allocate physical address space for those regions.
  * Allocate and insert a new resource to cover a free, unclaimed by a
  * descendant of @base, range in the span of @base.
  */
 struct resource *alloc_free_mem_region(struct resource *base,
                        unsigned long size, unsigned long align,
                        const char *name)
 {
     /* Default of ascending direction and insert resource */
     unsigned long flags = 0;
 
     return get_free_mem_region(NULL, base, size, align, name,
                    IORES_DESC_NONE, flags);
 }
 EXPORT_SYMBOL_NS_GPL(alloc_free_mem_region, CXL);
 #endif /* CONFIG_GET_FREE_REGION */
 
 static int __init strict_iomem(char *str)
 {
     if (strstr(str, "relaxed"))
         strict_iomem_checks = 0;
     if (strstr(str, "strict"))
         strict_iomem_checks = 1;
     return 1;
 }
 
 static int iomem_fs_init_fs_context(struct fs_context *fc)
 {
     return init_pseudo(fc, DEVMEM_MAGIC) ? 0 : -ENOMEM;
 }
 
 static struct file_system_type iomem_fs_type = {
     .name       = "iomem",
     .owner      = THIS_MODULE,
     .init_fs_context = iomem_fs_init_fs_context,
     .kill_sb    = kill_anon_super,
 };
 
 static int __init iomem_init_inode(void)
 {
     static struct vfsmount *iomem_vfs_mount;
     static int iomem_fs_cnt;
     struct inode *inode;
     int rc;
 
     rc = simple_pin_fs(&iomem_fs_type, &iomem_vfs_mount, &iomem_fs_cnt);
     if (rc < 0) {
         pr_err("Cannot mount iomem pseudo filesystem: %d\n", rc);
         return rc;
     }
 
     inode = alloc_anon_inode(iomem_vfs_mount->mnt_sb);
     if (IS_ERR(inode)) {
         rc = PTR_ERR(inode);
         pr_err("Cannot allocate inode for iomem: %d\n", rc);
         simple_release_fs(&iomem_vfs_mount, &iomem_fs_cnt);
         return rc;
     }
 
     /*
      * Publish iomem revocation inode initialized.
      * Pairs with smp_load_acquire() in revoke_iomem().
      */
     smp_store_release(&iomem_inode, inode);
 
     return 0;
 }
 
 fs_initcall(iomem_init_inode);
 
 __setup("iomem=", strict_iomem);

This page was automatically generated by the 2.1.0 LXR engine. The LXR team