patchbot at xen
Aug 8, 2013, 10:24 PM
Post #1 of 1
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[xen master] mem_sharing_nominate_page: p2mt should never change before p2m_change_type()
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commit fa89d08f329e495f20a561a0dac80c325c8b7784
Author: Nai Xia <nai.xia [at] gmail>
AuthorDate: Wed Aug 7 00:25:48 2013 +0800
Commit: Tim Deegan <tim [at] xen>
CommitDate: Thu Aug 8 11:19:46 2013 +0100
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 [at] gmail>
Acked-by: Andres Lagar-Cavilla <andres [at] lagarcavilla>
Acked-by: Tim Deegan <tim [at] xen>
---
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 0364bb0..1e89f6c 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);
--
generated by git-patchbot for /home/xen/git/xen.git#master
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