From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41540) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XtyCp-0005Xd-Ia for qemu-devel@nongnu.org; Thu, 27 Nov 2014 07:30:02 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XtyCj-0004FJ-DM for qemu-devel@nongnu.org; Thu, 27 Nov 2014 07:29:55 -0500 Received: from mx1.redhat.com ([209.132.183.28]:36775) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XtyCj-0004F4-6G for qemu-devel@nongnu.org; Thu, 27 Nov 2014 07:29:49 -0500 From: Stefan Hajnoczi Date: Thu, 27 Nov 2014 12:29:26 +0000 Message-Id: <1417091366-4469-7-git-send-email-stefanha@redhat.com> In-Reply-To: <1417091366-4469-1-git-send-email-stefanha@redhat.com> References: <1417091366-4469-1-git-send-email-stefanha@redhat.com> Subject: [Qemu-devel] [RFC 6/6] memory: make cpu_physical_memory_sync_dirty_bitmap() fully atomic List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Peter Maydell , Paolo Bonzini , rth@redhat.com, Stefan Hajnoczi , Juan Quintela 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 --- include/exec/ram_addr.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h index cdcbe9a..3d2a4c1 100644 --- a/include/exec/ram_addr.h +++ b/include/exec/ram_addr.h @@ -195,13 +195,13 @@ uint64_t cpu_physical_memory_sync_dirty_bitmap(unsigned long *dest, unsigned long *src = ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION]; for (k = page; k < page + nr; k++) { - if (src[k]) { + unsigned long bits = atomic_xchg(&src[k], 0); + if (bits) { 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 { -- 2.1.0