From: Stefan Hajnoczi <stefa...@redhat.com>
The fast path of cpu_physical_memory_sync_dirty_bitmap() directly
manipulates the dirty bitmap. Use atomic_xchg() to make the
test-and-clear atomic.
Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
Message-Id: <1417519399-3166-7-git-send-email-stefa...@redhat.com>
[Only do xchg on nonzero words. - Paolo]
Reviewed-by: Fam Zheng <f...@redhat.com>
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
include/exec/ram_addr.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
index a2beea7..c113f21 100644
--- a/include/exec/ram_addr.h
+++ b/include/exec/ram_addr.h
@@ -224,12 +224,12 @@ uint64_t cpu_physical_memory_sync_dirty_bitmap(unsigned
long *dest,
for (k = page; k < page + nr; k++) {
if (src[k]) {
+ unsigned long bits = atomic_xchg(&src[k], 0);
unsigned long new_dirty;
new_dirty = ~dest[k];
- dest[k] |= src[k];
- new_dirty &= src[k];
+ dest[k] |= bits;
+ new_dirty &= bits;
num_dirty += ctpopl(new_dirty);
- src[k] = 0;
}
}
} else {
--
2.4.1
