diff options
| author | Paolo Bonzini <pbonzini@redhat.com> | 2016-06-09 13:06:08 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2016-08-04 13:52:21 +0200 |
| commit | 3aed64f6d341cdb62bb2d6232589fb13448ce063 (patch) | |
| tree | 33c7906993c84a861d4575a19a667bb5d8749046 /arch/x86/kernel/pvclock.c | |
| parent | 96b585267f552d4b6a28ea8bd75e5ed03deb6e71 (diff) | |
pvclock: introduce seqcount-like API
The version field in struct pvclock_vcpu_time_info basically implements
a seqcount. Wrap it with the usual read_begin and read_retry functions,
and use these APIs instead of peppering the code with smp_rmb()s.
While at it, change it to the more pedantically correct virt_rmb().
With this change, __pvclock_read_cycles can be simplified noticeably.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kernel/pvclock.c')
| -rw-r--r-- | arch/x86/kernel/pvclock.c | 17 |
1 files changed, 6 insertions, 11 deletions
diff --git a/arch/x86/kernel/pvclock.c b/arch/x86/kernel/pvclock.c index 06c58ce46762..3599404e3089 100644 --- a/arch/x86/kernel/pvclock.c +++ b/arch/x86/kernel/pvclock.c @@ -64,14 +64,9 @@ u8 pvclock_read_flags(struct pvclock_vcpu_time_info *src) u8 flags; do { - version = src->version; - /* Make the latest version visible */ - smp_rmb(); - + version = pvclock_read_begin(src); flags = src->flags; - /* Make sure that the version double-check is last. */ - smp_rmb(); - } while ((src->version & 1) || version != src->version); + } while (pvclock_read_retry(src, version)); return flags & valid_flags; } @@ -84,10 +79,10 @@ cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src) u8 flags; do { - version = __pvclock_read_cycles(src, &ret, &flags); - /* Make sure that the version double-check is last. */ - smp_rmb(); - } while ((src->version & 1) || version != src->version); + version = pvclock_read_begin(src); + ret = __pvclock_read_cycles(src); + flags = src->flags; + } while (pvclock_read_retry(src, version)); if (unlikely((flags & PVCLOCK_GUEST_STOPPED) != 0)) { src->flags &= ~PVCLOCK_GUEST_STOPPED; |