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[PATCH] i386/x86-64: Don't call change_page_attr with a spinlock held

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It's illegal because it can sleep.

Use a two step lookup scheme instead.  First look up the vm_struct, then
change the direct mapping, then finally unmap it.  That's ok because nobody
can change the particular virtual address range as long as the vm_struct is
still in the global list.

Also added some LinuxDoc documentation to iounmap.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Andi Kleen 2005-12-12 22:17:09 -08:00 committed by Linus Torvalds
parent 5e9ef02ec0
commit bf5421c309
2 changed files with 60 additions and 14 deletions
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37
arch/i386/mm/ioremap.c
View File

@ -223,9 +223,15 @@ void __iomem *ioremap_nocache (unsigned long phys_addr, unsigned long size)
} }
EXPORT_SYMBOL(ioremap_nocache); EXPORT_SYMBOL(ioremap_nocache);
/**
* 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) void iounmap(volatile void __iomem *addr)
{ {
struct vm_struct *p; struct vm_struct *p, *o;
if ((void __force *)addr <= high_memory) if ((void __force *)addr <= high_memory)
return; return;
@ -239,22 +245,37 @@ void iounmap(volatile void __iomem *addr)
addr < phys_to_virt(ISA_END_ADDRESS)) addr < phys_to_virt(ISA_END_ADDRESS))
return; return;
write_lock(&vmlist_lock); addr = (volatile void *)(PAGE_MASK & (unsigned long __force)addr);
p = __remove_vm_area((void *)(PAGE_MASK & (unsigned long __force)addr));
if (!p) { /* Use the vm area unlocked, assuming the caller
printk(KERN_WARNING "iounmap: bad address %p\n", addr); 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);
dump_stack(); dump_stack();
goto out_unlock; return;
} }
/* Reset the direct mapping. Can block */
if ((p->flags >> 20) && p->phys_addr < virt_to_phys(high_memory) - 1) { if ((p->flags >> 20) && p->phys_addr < virt_to_phys(high_memory) - 1) {
change_page_attr(virt_to_page(__va(p->phys_addr)), change_page_attr(virt_to_page(__va(p->phys_addr)),
p->size >> PAGE_SHIFT, p->size >> PAGE_SHIFT,
PAGE_KERNEL); PAGE_KERNEL);
global_flush_tlb(); global_flush_tlb();
} }
out_unlock:
write_unlock(&vmlist_lock); /* Finally remove it */
o = remove_vm_area((void *)addr);
BUG_ON(p != o || o == NULL);
kfree(p); kfree(p);
} }
EXPORT_SYMBOL(iounmap); EXPORT_SYMBOL(iounmap);

37
arch/x86_64/mm/ioremap.c
View File

@ -247,9 +247,15 @@ void __iomem *ioremap_nocache (unsigned long phys_addr, unsigned long size)
return __ioremap(phys_addr, size, _PAGE_PCD); 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) void iounmap(volatile void __iomem *addr)
{ {
struct vm_struct *p; struct vm_struct *p, *o;
if (addr <= high_memory) if (addr <= high_memory)
return; return;
@ -257,12 +263,31 @@ void iounmap(volatile void __iomem *addr)
addr < phys_to_virt(ISA_END_ADDRESS)) addr < phys_to_virt(ISA_END_ADDRESS))
return; return;
write_lock(&vmlist_lock); addr = (volatile void *)(PAGE_MASK & (unsigned long __force)addr);
p = __remove_vm_area((void *)((unsigned long)addr & PAGE_MASK)); /* Use the vm area unlocked, assuming the caller
if (!p) 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); 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); 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); kfree(p);
} }