459c1517f9
Achieve better usage of the DMA coherent region by doing top-down allocation rather than bottom up. If we ask for a 128kB allocation, this will be aligned to 128kB and satisfied from the very bottom address. If we then ask for a 600kB allocation, this will be aligned to 1MB, and we will have a 896kB hole. Performing top-down allocation resolves this by allocating the 128kB at the very top, and then the 600kB can come in below it without any unnecessary wastage. This problem was reported by Janusz Krzysztofik, who had 2 x 128kB + 1 x 640kB allocations which wouldn't fit into 1MB. Tested-by: Janusz Krzysztofik <jkrzyszt@tis.icnet.pl> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
132 lines
3.1 KiB
C
132 lines
3.1 KiB
C
#include <linux/spinlock.h>
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#include <linux/list.h>
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#include <linux/slab.h>
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#include "vmregion.h"
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/*
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* VM region handling support.
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*
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* This should become something generic, handling VM region allocations for
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* vmalloc and similar (ioremap, module space, etc).
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*
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* I envisage vmalloc()'s supporting vm_struct becoming:
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*
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* struct vm_struct {
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* struct vmregion region;
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* unsigned long flags;
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* struct page **pages;
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* unsigned int nr_pages;
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* unsigned long phys_addr;
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* };
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*
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* get_vm_area() would then call vmregion_alloc with an appropriate
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* struct vmregion head (eg):
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*
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* struct vmregion vmalloc_head = {
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* .vm_list = LIST_HEAD_INIT(vmalloc_head.vm_list),
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* .vm_start = VMALLOC_START,
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* .vm_end = VMALLOC_END,
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* };
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*
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* However, vmalloc_head.vm_start is variable (typically, it is dependent on
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* the amount of RAM found at boot time.) I would imagine that get_vm_area()
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* would have to initialise this each time prior to calling vmregion_alloc().
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*/
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struct arm_vmregion *
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arm_vmregion_alloc(struct arm_vmregion_head *head, size_t align,
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size_t size, gfp_t gfp)
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{
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unsigned long start = head->vm_start, addr = head->vm_end;
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unsigned long flags;
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struct arm_vmregion *c, *new;
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if (head->vm_end - head->vm_start < size) {
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printk(KERN_WARNING "%s: allocation too big (requested %#x)\n",
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__func__, size);
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goto out;
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}
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new = kmalloc(sizeof(struct arm_vmregion), gfp);
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if (!new)
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goto out;
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spin_lock_irqsave(&head->vm_lock, flags);
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addr = rounddown(addr - size, align);
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list_for_each_entry_reverse(c, &head->vm_list, vm_list) {
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if (addr >= c->vm_end)
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goto found;
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addr = rounddown(c->vm_start - size, align);
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if (addr < start)
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goto nospc;
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}
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found:
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/*
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* Insert this entry after the one we found.
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*/
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list_add(&new->vm_list, &c->vm_list);
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new->vm_start = addr;
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new->vm_end = addr + size;
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new->vm_active = 1;
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spin_unlock_irqrestore(&head->vm_lock, flags);
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return new;
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nospc:
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spin_unlock_irqrestore(&head->vm_lock, flags);
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kfree(new);
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out:
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return NULL;
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}
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static struct arm_vmregion *__arm_vmregion_find(struct arm_vmregion_head *head, unsigned long addr)
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{
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struct arm_vmregion *c;
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list_for_each_entry(c, &head->vm_list, vm_list) {
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if (c->vm_active && c->vm_start == addr)
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goto out;
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}
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c = NULL;
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out:
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return c;
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}
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struct arm_vmregion *arm_vmregion_find(struct arm_vmregion_head *head, unsigned long addr)
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{
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struct arm_vmregion *c;
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unsigned long flags;
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spin_lock_irqsave(&head->vm_lock, flags);
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c = __arm_vmregion_find(head, addr);
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spin_unlock_irqrestore(&head->vm_lock, flags);
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return c;
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}
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struct arm_vmregion *arm_vmregion_find_remove(struct arm_vmregion_head *head, unsigned long addr)
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{
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struct arm_vmregion *c;
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unsigned long flags;
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spin_lock_irqsave(&head->vm_lock, flags);
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c = __arm_vmregion_find(head, addr);
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if (c)
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c->vm_active = 0;
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spin_unlock_irqrestore(&head->vm_lock, flags);
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return c;
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}
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void arm_vmregion_free(struct arm_vmregion_head *head, struct arm_vmregion *c)
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{
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unsigned long flags;
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spin_lock_irqsave(&head->vm_lock, flags);
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list_del(&c->vm_list);
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spin_unlock_irqrestore(&head->vm_lock, flags);
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kfree(c);
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}
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