[Xen-changelog] [xen stable-4.4] VT-d/qinval: make local variable used for communication with IOMMU "volatile"

[patchbot@xxxxxxx]

commit a5d7d7a6dc79f618f7f8baabe4561c40a0820650
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Jun 24 09:43:31 2014 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Jun 24 09:43:31 2014 +0200

    VT-d/qinval: make local variable used for communication with IOMMU 
"volatile"
    
    Without that there is - afaict - nothing preventing the compiler from
    putting the variable into a register for the duration of the wait loop.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Acked-by: Yang Zhang <yang.z.zhang@xxxxxxxxx>
    master commit: ceec46c02074e1b2ade0b13c3c4a2f3942ae698c
    master date: 2014-06-20 10:25:33 +0200
---
 xen/drivers/passthrough/vtd/qinval.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/xen/drivers/passthrough/vtd/qinval.c 
b/xen/drivers/passthrough/vtd/qinval.c
index ef5de99..fe29e82 100644
--- a/xen/drivers/passthrough/vtd/qinval.c
+++ b/xen/drivers/passthrough/vtd/qinval.c
@@ -196,7 +196,7 @@ static int queue_invalidate_wait(struct iommu *iommu,
     u8 iflag, u8 sw, u8 fn)
 {
     s_time_t start_time;
-    u32 poll_slot = QINVAL_STAT_INIT;
+    volatile u32 poll_slot = QINVAL_STAT_INIT;
     int index = -1;
     int ret = -1;
     unsigned long flags;
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.4

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