From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57580) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gNF5B-0003hW-KW for qemu-devel@nongnu.org; Thu, 15 Nov 2018 05:41:11 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gNF57-0000pA-BR for qemu-devel@nongnu.org; Thu, 15 Nov 2018 05:41:09 -0500 Received: from mga03.intel.com ([134.134.136.65]:14567) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gNF57-0000oM-2h for qemu-devel@nongnu.org; Thu, 15 Nov 2018 05:41:05 -0500 From: Wei Wang Date: Thu, 15 Nov 2018 18:07:57 +0800 Message-Id: <1542276484-25508-2-git-send-email-wei.w.wang@intel.com> In-Reply-To: <1542276484-25508-1-git-send-email-wei.w.wang@intel.com> References: <1542276484-25508-1-git-send-email-wei.w.wang@intel.com> Subject: [Qemu-devel] [PATCH v9 1/8] bitmap: fix bitmap_count_one List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org, virtio-dev@lists.oasis-open.org, mst@redhat.com, quintela@redhat.com, dgilbert@redhat.com Cc: peterx@redhat.com, pbonzini@redhat.com, liliang.opensource@gmail.com, nilal@redhat.com, riel@redhat.com, wei.w.wang@intel.com BITMAP_LAST_WORD_MASK(nbits) returns 0xffffffff when "nbits=0", which makes bitmap_count_one fail to handle the "nbits=0" case. It appears to be preferred to remain BITMAP_LAST_WORD_MASK identical to the kernel implementation that it is ported from. So this patch fixes bitmap_count_one to handle the nbits=0 case. Inital Discussion Link: https://www.mail-archive.com/qemu-devel@nongnu.org/msg554316.html Signed-off-by: Wei Wang CC: Juan Quintela CC: Dr. David Alan Gilbert CC: Peter Xu --- include/qemu/bitmap.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/include/qemu/bitmap.h b/include/qemu/bitmap.h index 509eedd..679f1bd 100644 --- a/include/qemu/bitmap.h +++ b/include/qemu/bitmap.h @@ -221,6 +221,10 @@ static inline int bitmap_intersects(const unsigned long *src1, static inline long bitmap_count_one(const unsigned long *bitmap, long nbits) { + if (unlikely(!nbits)) { + return 0; + } + if (small_nbits(nbits)) { return ctpopl(*bitmap & BITMAP_LAST_WORD_MASK(nbits)); } else { -- 1.8.3.1