Logo Search packages:      
Sourcecode: linux version File versions  Download package

vmregion.c

#include <linux/spinlock.h>
#include <linux/list.h>
#include <linux/slab.h>

#include "vmregion.h"

/*
 * VM region handling support.
 *
 * This should become something generic, handling VM region allocations for
 * vmalloc and similar (ioremap, module space, etc).
 *
 * I envisage vmalloc()'s supporting vm_struct becoming:
 *
 *  struct vm_struct {
 *    struct vmregion   region;
 *    unsigned long     flags;
 *    struct page **pages;
 *    unsigned int      nr_pages;
 *    unsigned long     phys_addr;
 *  };
 *
 * get_vm_area() would then call vmregion_alloc with an appropriate
 * struct vmregion head (eg):
 *
 *  struct vmregion vmalloc_head = {
 *    .vm_list    = LIST_HEAD_INIT(vmalloc_head.vm_list),
 *    .vm_start   = VMALLOC_START,
 *    .vm_end           = VMALLOC_END,
 *  };
 *
 * However, vmalloc_head.vm_start is variable (typically, it is dependent on
 * the amount of RAM found at boot time.)  I would imagine that get_vm_area()
 * would have to initialise this each time prior to calling vmregion_alloc().
 */

struct arm_vmregion *
arm_vmregion_alloc(struct arm_vmregion_head *head, size_t align,
               size_t size, gfp_t gfp)
{
      unsigned long addr = head->vm_start, end = head->vm_end - size;
      unsigned long flags;
      struct arm_vmregion *c, *new;

      if (head->vm_end - head->vm_start < size) {
            printk(KERN_WARNING "%s: allocation too big (requested %#x)\n",
                  __func__, size);
            goto out;
      }

      new = kmalloc(sizeof(struct arm_vmregion), gfp);
      if (!new)
            goto out;

      spin_lock_irqsave(&head->vm_lock, flags);

      list_for_each_entry(c, &head->vm_list, vm_list) {
            if ((addr + size) < addr)
                  goto nospc;
            if ((addr + size) <= c->vm_start)
                  goto found;
            addr = ALIGN(c->vm_end, align);
            if (addr > end)
                  goto nospc;
      }

 found:
      /*
       * Insert this entry _before_ the one we found.
       */
      list_add_tail(&new->vm_list, &c->vm_list);
      new->vm_start = addr;
      new->vm_end = addr + size;
      new->vm_active = 1;

      spin_unlock_irqrestore(&head->vm_lock, flags);
      return new;

 nospc:
      spin_unlock_irqrestore(&head->vm_lock, flags);
      kfree(new);
 out:
      return NULL;
}

static struct arm_vmregion *__arm_vmregion_find(struct arm_vmregion_head *head, unsigned long addr)
{
      struct arm_vmregion *c;

      list_for_each_entry(c, &head->vm_list, vm_list) {
            if (c->vm_active && c->vm_start == addr)
                  goto out;
      }
      c = NULL;
 out:
      return c;
}

struct arm_vmregion *arm_vmregion_find(struct arm_vmregion_head *head, unsigned long addr)
{
      struct arm_vmregion *c;
      unsigned long flags;

      spin_lock_irqsave(&head->vm_lock, flags);
      c = __arm_vmregion_find(head, addr);
      spin_unlock_irqrestore(&head->vm_lock, flags);
      return c;
}

struct arm_vmregion *arm_vmregion_find_remove(struct arm_vmregion_head *head, unsigned long addr)
{
      struct arm_vmregion *c;
      unsigned long flags;

      spin_lock_irqsave(&head->vm_lock, flags);
      c = __arm_vmregion_find(head, addr);
      if (c)
            c->vm_active = 0;
      spin_unlock_irqrestore(&head->vm_lock, flags);
      return c;
}

void arm_vmregion_free(struct arm_vmregion_head *head, struct arm_vmregion *c)
{
      unsigned long flags;

      spin_lock_irqsave(&head->vm_lock, flags);
      list_del(&c->vm_list);
      spin_unlock_irqrestore(&head->vm_lock, flags);

      kfree(c);
}

Generated by  Doxygen 1.6.0   Back to index