From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44324) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1d32Cf-0008Sz-Da for qemu-devel@nongnu.org; Tue, 25 Apr 2017 11:16:36 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1d32CZ-0005Yw-Nl for qemu-devel@nongnu.org; Tue, 25 Apr 2017 11:16:33 -0400 Date: Tue, 25 Apr 2017 17:16:10 +0200 From: Kevin Wolf Message-ID: <20170425151610.GC4615@noname.redhat.com> References: <20170410150542.30376-1-famz@redhat.com> <20170410150542.30376-11-famz@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170410150542.30376-11-famz@redhat.com> Subject: Re: [Qemu-devel] [PATCH for 2.9 v3 10/10] block: Fix bdrv_co_flush early return List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Fam Zheng Cc: qemu-devel@nongnu.org, Paolo Bonzini , qemu-block@nongnu.org, Ed Swierk , Max Reitz , Eric Blake , Stefan Hajnoczi Am 10.04.2017 um 17:05 hat Fam Zheng geschrieben: > bdrv_inc_in_flight and bdrv_dec_in_flight are mandatory for > BDRV_POLL_WHILE to work, even for the shortcut case where flush is > unnecessary. Move the if block to below bdrv_dec_in_flight, and BTW fix > the variable declaration position. > > Signed-off-by: Fam Zheng > --- > block/io.c | 16 +++++++++------- > 1 file changed, 9 insertions(+), 7 deletions(-) > > diff --git a/block/io.c b/block/io.c > index 00e45ca..bae6947 100644 > --- a/block/io.c > +++ b/block/io.c > @@ -2278,16 +2278,17 @@ static void coroutine_fn bdrv_flush_co_entry(void *opaque) > > int coroutine_fn bdrv_co_flush(BlockDriverState *bs) > { > - int ret; > - > - if (!bs || !bdrv_is_inserted(bs) || bdrv_is_read_only(bs) || > - bdrv_is_sg(bs)) { > - return 0; > - } > + int current_gen; > + int ret = 0; > > bdrv_inc_in_flight(bs); As Coverity points out, we're now using bs... > - int current_gen = bs->write_gen; > + if (!bs || !bdrv_is_inserted(bs) || bdrv_is_read_only(bs) || ...before doing the NULL check. I'm not sure if we even need to have a NULL check here, but we would have to check all callers to make sure that it's unnecessary. Before commit 29cdb251, it only checked bs->drv and I don't see how that commit introduced a NULL caller, but maybe one was added later. In any case, bdrv_co_flush() needs a fix, either remove the NULL check or do it first. > + bdrv_is_sg(bs)) { > + goto early_exit; > + } Kevin