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Diffstat (limited to 'arch/x86_64/mm/ioremap.c')
-rw-r--r--arch/x86_64/mm/ioremap.c37
1 files changed, 31 insertions, 6 deletions
diff --git a/arch/x86_64/mm/ioremap.c b/arch/x86_64/mm/ioremap.c
index ecf7acb5db9..0d260e4492f 100644
--- a/arch/x86_64/mm/ioremap.c
+++ b/arch/x86_64/mm/ioremap.c
@@ -247,9 +247,15 @@ void __iomem *ioremap_nocache (unsigned long phys_addr, unsigned long size)
return __ioremap(phys_addr, size, _PAGE_PCD);
}
+/**
+ * iounmap - Free a IO remapping
+ * @addr: virtual address from ioremap_*
+ *
+ * Caller must ensure there is only one unmapping for the same pointer.
+ */
void iounmap(volatile void __iomem *addr)
{
- struct vm_struct *p;
+ struct vm_struct *p, *o;
if (addr <= high_memory)
return;
@@ -257,12 +263,31 @@ void iounmap(volatile void __iomem *addr)
addr < phys_to_virt(ISA_END_ADDRESS))
return;
- write_lock(&vmlist_lock);
- p = __remove_vm_area((void *)((unsigned long)addr & PAGE_MASK));
- if (!p)
+ addr = (volatile void *)(PAGE_MASK & (unsigned long __force)addr);
+ /* Use the vm area unlocked, assuming the caller
+ ensures there isn't another iounmap for the same address
+ in parallel. Reuse of the virtual address is prevented by
+ leaving it in the global lists until we're done with it.
+ cpa takes care of the direct mappings. */
+ read_lock(&vmlist_lock);
+ for (p = vmlist; p; p = p->next) {
+ if (p->addr == addr)
+ break;
+ }
+ read_unlock(&vmlist_lock);
+
+ if (!p) {
printk("iounmap: bad address %p\n", addr);
- else if (p->flags >> 20)
+ dump_stack();
+ return;
+ }
+
+ /* Reset the direct mapping. Can block */
+ if (p->flags >> 20)
ioremap_change_attr(p->phys_addr, p->size, 0);
- write_unlock(&vmlist_lock);
+
+ /* Finally remove it */
+ o = remove_vm_area((void *)addr);
+ BUG_ON(p != o || o == NULL);
kfree(p);
}