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| author | Yang Xiaowei <xiaowei.yang@intel.com> | 2009-09-09 21:44:52 +0200 |
|---|---|---|
| committer | Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> | 2009-09-10 01:38:44 +0200 |
| commit | 2496afbf1e50c70f80992656bcb730c8583ddac3 (patch) | |
| tree | fd701f588d8194cb1b296eca9c6288b6b8c342a1 /drivers/ata | |
| parent | xen: only enable interrupts while actually blocking for spinlock (diff) | |
| download | linux-2496afbf1e50c70f80992656bcb730c8583ddac3.tar.xz linux-2496afbf1e50c70f80992656bcb730c8583ddac3.zip | |
xen: use stronger barrier after unlocking lock
We need to have a stronger barrier between releasing the lock and
checking for any waiting spinners. A compiler barrier is not sufficient
because the CPU's ordering rules do not prevent the read xl->spinners
from happening before the unlock assignment, as they are different
memory locations.
We need to have an explicit barrier to enforce the write-read ordering
to different memory locations.
Because of it, I can't bring up > 4 HVM guests on one SMP machine.
[ Code and commit comments expanded -J ]
[ Impact: avoid deadlock when using Xen PV spinlocks ]
Signed-off-by: Yang Xiaowei <xiaowei.yang@intel.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Diffstat (limited to 'drivers/ata')
0 files changed, 0 insertions, 0 deletions