From bf5421c309bb89e5106452bc840983b1b4754d61 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Mon, 12 Dec 2005 22:17:09 -0800 Subject: [PATCH] i386/x86-64: Don't call change_page_attr with a spinlock held 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/i386/mm/ioremap.c | 37 +++++++++++++++++++++++++++++-------- 1 file changed, 29 insertions(+), 8 deletions(-) (limited to 'arch/i386/mm') diff --git a/arch/i386/mm/ioremap.c b/arch/i386/mm/ioremap.c index 5d09de8d1c6..8498b5ac395 100644 --- a/arch/i386/mm/ioremap.c +++ b/arch/i386/mm/ioremap.c @@ -223,9 +223,15 @@ void __iomem *ioremap_nocache (unsigned long phys_addr, unsigned long size) } 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) { - struct vm_struct *p; + struct vm_struct *p, *o; if ((void __force *)addr <= high_memory) return; @@ -239,22 +245,37 @@ void iounmap(volatile void __iomem *addr) addr < phys_to_virt(ISA_END_ADDRESS)) return; - write_lock(&vmlist_lock); - p = __remove_vm_area((void *)(PAGE_MASK & (unsigned long __force)addr)); - if (!p) { - printk(KERN_WARNING "iounmap: bad address %p\n", addr); + 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); 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) { change_page_attr(virt_to_page(__va(p->phys_addr)), p->size >> PAGE_SHIFT, PAGE_KERNEL); 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); } EXPORT_SYMBOL(iounmap); -- cgit v1.2.3