From: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Date: Fri, 7 Jan 2011 11:51:47 +0000 (+0000)
Subject: xen/gntdev: Fix circular locking dependency
X-Git-Tag: v2.6.38-rc1~72^2~5
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f0a70c882ea546bbd802643990ceded32c39facc;p=pandora-kernel.git

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>
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