From f0a70c882ea546bbd802643990ceded32c39facc Mon Sep 17 00:00:00 2001 From: Daniel De Graaf Date: Fri, 7 Jan 2011 11:51:47 +0000 Subject: [PATCH] xen/gntdev: Fix circular locking dependency apply_to_page_range will acquire PTE lock while priv->lock is held, and mn_invl_range_start tries to acquire priv->lock with PTE already held. Fix by not holding priv->lock during the entire map operation. This is safe because map->vma is set nonzero while the lock is held, which will cause subsequent maps to fail and will cause the unmap ioctl (and other users of gntdev_del_map) to return -EBUSY until the area is unmapped. It is similarly impossible for gntdev_vma_close to be called while the vma is still being created. Signed-off-by: Daniel De Graaf Signed-off-by: Konrad Rzeszutek Wilk --- drivers/xen/gntdev.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c index a2ea5335e152..aba76d437ea8 100644 --- a/drivers/xen/gntdev.c +++ b/drivers/xen/gntdev.c @@ -575,21 +575,26 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma) if (!(vma->vm_flags & VM_WRITE)) map->flags |= GNTMAP_readonly; + spin_unlock(&priv->lock); + err = apply_to_page_range(vma->vm_mm, vma->vm_start, vma->vm_end - vma->vm_start, find_grant_ptes, map); if (err) { printk(KERN_WARNING "find_grant_ptes() failure.\n"); - goto unlock_out; + return err; } err = map_grant_pages(map); if (err) { printk(KERN_WARNING "map_grant_pages() failure.\n"); - goto unlock_out; + return err; } + map->is_mapped = 1; + return 0; + unlock_out: spin_unlock(&priv->lock); return err; -- 2.20.1