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| author | Keir Fraser <keir@xen.org> | 2011-01-08 10:09:44 +0000 |
|---|---|---|
| committer | Keir Fraser <keir@xen.org> | 2011-01-08 10:09:44 +0000 |
| commit | d8ec7a2381c2b26ea518610fa95c507c6872bdfa (patch) | |
| tree | 1c520feb146f6c0ff6ff80d82d3e4a245f0b0927 /xen/include/xen/timer.h | |
| parent | 44260b1a73a53f015530798438c20301f0858173 (diff) | |
| download | xen-d8ec7a2381c2b26ea518610fa95c507c6872bdfa.tar.gz xen-d8ec7a2381c2b26ea518610fa95c507c6872bdfa.tar.bz2 xen-d8ec7a2381c2b26ea518610fa95c507c6872bdfa.zip | |
timer: Ensure that CPU field of a timer is read safely when lock-free.
Firstly, all updates must use atomic_write16(), and lock-free reads
must use atomic_read16(). Secondly, we ensure ->cpu is the only field
accessed without a lock. This requires us to place a special sentinel
value in that field when a timer is killed, to avoid needing to read
->status outside a locked critical section.
Signed-off-by: Keir Fraser <keir@xen.org>
Diffstat (limited to 'xen/include/xen/timer.h')
| -rw-r--r-- | xen/include/xen/timer.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/xen/include/xen/timer.h b/xen/include/xen/timer.h index e8b80f248e..d2091420d7 100644 --- a/xen/include/xen/timer.h +++ b/xen/include/xen/timer.h @@ -32,6 +32,7 @@ struct timer { void *data; /* CPU on which this timer will be installed and executed. */ +#define TIMER_CPU_status_killed 0xffffu /* Timer is TIMER_STATUS_killed */ uint16_t cpu; /* Timer status. */ |