From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56753) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YnLin-0004LB-MA for qemu-devel@nongnu.org; Wed, 29 Apr 2015 02:43:50 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YnLii-0000dH-Nn for qemu-devel@nongnu.org; Wed, 29 Apr 2015 02:43:49 -0400 Date: Wed, 29 Apr 2015 08:43:35 +0200 From: Thomas Huth Message-ID: <20150429084335.24fbeb31@thh440s> In-Reply-To: <55407B8B.1010803@msgid.tls.msk.ru> References: <1430153944-24368-1-git-send-email-thuth@redhat.com> <55407B8B.1010803@msgid.tls.msk.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [Qemu-trivial] [PATCH] kvm: Silence warning from valgrind List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Michael Tokarev Cc: qemu-trivial@nongnu.org, Paolo Bonzini , qemu-devel@nongnu.org On Wed, 29 Apr 2015 09:34:51 +0300 Michael Tokarev wrote: > 27.04.2015 19:59, Thomas Huth wrote: > > valgrind complains here about uninitialized bytes with the following message: > > > > ==17814== Syscall param ioctl(generic) points to uninitialised byte(s) > > ==17814== at 0x466A780: ioctl (in /usr/lib64/power8/libc-2.17.so) > > ==17814== by 0x100735B7: kvm_vm_ioctl (kvm-all.c:1920) > > ==17814== by 0x10074583: kvm_set_ioeventfd_mmio (kvm-all.c:574) > > > > Let's fix it by using a proper struct initializer in kvm_set_ioeventfd_mmio(). > > > > Signed-off-by: Thomas Huth > > --- > > kvm-all.c | 14 +++++++------- > > 1 file changed, 7 insertions(+), 7 deletions(-) > > > > diff --git a/kvm-all.c b/kvm-all.c > > index dd44f8c..077b0ed 100644 > > --- a/kvm-all.c > > +++ b/kvm-all.c > > @@ -552,13 +552,13 @@ static int kvm_set_ioeventfd_mmio(int fd, hwaddr addr, uint32_t val, > > bool assign, uint32_t size, bool datamatch) > > { > > int ret; > > - struct kvm_ioeventfd iofd; > > - > > - iofd.datamatch = datamatch ? adjust_ioeventfd_endianness(val, size) : 0; > > - iofd.addr = addr; > > - iofd.len = size; > > - iofd.flags = 0; > > - iofd.fd = fd; > > + struct kvm_ioeventfd iofd = { > > + .datamatch = datamatch ? adjust_ioeventfd_endianness(val, size) : 0, > > + .addr = addr, > > + .len = size, > > + .flags = 0, > > + .fd = fd, > > + }; > > Hm. So, what's the difference? The same fields are assigned the same > values, why in first case we have some uninitialized data and in second > case everything is initialized? Does struct initializer zero-fills all > other places (alignments, missing fields etc) ? Right, the struct initializer fills the remaining fields with zeros. > If yes, there's no need to assign zero to flags, btw ;) True. Shall I sent a patch without that line? Thomas