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author | Nai Xia <nai.xia@gmail.com> | 2013-08-07 00:25:48 +0800 |
---|---|---|
committer | Tim Deegan <tim@xen.org> | 2013-08-08 11:19:46 +0100 |
commit | fa89d08f329e495f20a561a0dac80c325c8b7784 (patch) | |
tree | b17e7d638ab34b8535ac2e36c97962edd49cb23f /xen | |
parent | da56976f30dcea66c09c2d63554228bbf8cc1d34 (diff) | |
download | xen-fa89d08f329e495f20a561a0dac80c325c8b7784.tar.gz xen-fa89d08f329e495f20a561a0dac80c325c8b7784.tar.bz2 xen-fa89d08f329e495f20a561a0dac80c325c8b7784.zip |
mem_sharing_nominate_page: p2mt should never change before p2m_change_type()
The p2mt change check for p2m_change_type() was first introduced when
this code path was not protected by p2m_lock(). Now this code path is
protected by p2m_lock. So p2mt should never change before
p2m_change_type().
Signed-off-by: Nai Xia <nai.xia@gmail.com>
Acked-by: Andres Lagar-Cavilla <andres@lagarcavilla.org>
Acked-by: Tim Deegan <tim@xen.org>
Diffstat (limited to 'xen')
-rw-r--r-- | xen/arch/x86/mm/mem_sharing.c | 16 |
1 files changed, 2 insertions, 14 deletions
diff --git a/xen/arch/x86/mm/mem_sharing.c b/xen/arch/x86/mm/mem_sharing.c index 0364bb048e..1e89f6c4fc 100644 --- a/xen/arch/x86/mm/mem_sharing.c +++ b/xen/arch/x86/mm/mem_sharing.c @@ -900,20 +900,8 @@ int mem_sharing_nominate_page(struct domain *d, goto out; } - /* Change the p2m type */ - if ( p2m_change_type(d, gfn, p2mt, p2m_ram_shared) != p2mt ) - { - /* This is unlikely, as the type must have changed since we've checked - * it a few lines above. - * The mfn needs to revert back to rw type. This should never fail, - * since no-one knew that the mfn was temporarily sharable */ - mem_sharing_gfn_destroy(page, d, gfn_info); - xfree(page->sharing); - page->sharing = NULL; - /* NOTE: We haven't yet added this to the audit list. */ - BUG_ON(page_make_private(d, page) != 0); - goto out; - } + /* Change the p2m type, should never fail with p2m locked. */ + BUG_ON(p2m_change_type(d, gfn, p2mt, p2m_ram_shared) != p2mt); /* Account for this page. */ atomic_inc(&nr_shared_mfns); |