From 5f2cb94688bd0b2c88e0fc1ac3c4582965b7b106 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Tue, 2 Dec 2014 11:23:19 +0000 Subject: memory: make cpu_physical_memory_sync_dirty_bitmap() fully atomic 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 Message-Id: <1417519399-3166-7-git-send-email-stefanha@redhat.com> [Only do xchg on nonzero words. - Paolo] Reviewed-by: Fam Zheng Signed-off-by: Paolo Bonzini --- include/exec/ram_addr.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'include/exec/ram_addr.h') diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h index a2beea7925..c113f21140 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 { -- cgit v1.2.1