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authorDaniel De Graaf <dgdegra@tycho.nsa.gov>2011-01-07 11:51:47 +0000
committerKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2011-01-11 14:31:47 -0500
commitf0a70c882ea546bbd802643990ceded32c39facc (patch)
tree3544db8b681c4bd513758579afc4847e2e87ecbf
parentba5d1012292403c8037adf4a54c4ec50dfe846c4 (diff)
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 <dgdegra@tycho.nsa.gov> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
-rw-r--r--drivers/xen/gntdev.c9
1 files 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;