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Wed, 8 Jan 2020 12:40:59 +0000 (UTC) Received: from redhat.com (unknown [10.36.118.112]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D2FB860BE2; Wed, 8 Jan 2020 12:40:58 +0000 (UTC) From: Juan Quintela To: "Dr. David Alan Gilbert" Subject: Re: [PATCH 1/4] qemu-file: Don't do IO after shutdown In-Reply-To: <20200108094944.GA3184@work-vm> (David Alan Gilbert's message of "Wed, 8 Jan 2020 09:49:44 +0000") References: <20191218050439.5989-1-quintela@redhat.com> <20191218050439.5989-2-quintela@redhat.com> <20191218122702.GF3707@work-vm> <20200108094944.GA3184@work-vm> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) Date: Wed, 08 Jan 2020 13:40:55 +0100 Message-ID: <87d0bui0iw.fsf@secure.laptop> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-MC-Unique: aggE3JvuNWKvwQj-d5UKcQ-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 205.139.110.120 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: quintela@redhat.com Cc: Laurent Vivier , Paolo Bonzini , Thomas Huth , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" "Dr. David Alan Gilbert" wrote: > * Dr. David Alan Gilbert (dgilbert@redhat.com) wrote: >> * Juan Quintela (quintela@redhat.com) wrote: >> > Be sure that we are not doing neither read/write after shutdown of the >> > QEMUFile. >> >=20 >> > Signed-off-by: Juan Quintela >> > --- >> > migration/qemu-file.c | 13 +++++++++++++ >> > 1 file changed, 13 insertions(+) >> >=20 >> > diff --git a/migration/qemu-file.c b/migration/qemu-file.c >> > index 26fb25ddc1..1e5543a279 100644 >> > --- a/migration/qemu-file.c >> > +++ b/migration/qemu-file.c >> > @@ -53,6 +53,8 @@ struct QEMUFile { >> > =20 >> > int last_error; >> > Error *last_error_obj; >> > + /* has the file has been shutdown */ >> > + bool shutdown; >> > }; >> > =20 >> > /* >> > @@ -61,6 +63,7 @@ struct QEMUFile { >> > */ >> > int qemu_file_shutdown(QEMUFile *f) >> > { >> > + f->shutdown =3D true; >> > if (!f->ops->shut_down) { >> > return -ENOSYS; >> > } >> > @@ -214,6 +217,9 @@ void qemu_fflush(QEMUFile *f) >> > return; >> > } >> > =20 >> > + if (f->shutdown) { >> > + return; >> > + } >>=20 >> OK, I did wonder if you need to free the iovec. >>=20 >> > if (f->iovcnt > 0) { >> > expect =3D iov_size(f->iov, f->iovcnt); >> > ret =3D f->ops->writev_buffer(f->opaque, f->iov, f->iovcnt, f= ->pos, >> > @@ -328,6 +334,10 @@ static ssize_t qemu_fill_buffer(QEMUFile *f) >> > f->buf_index =3D 0; >> > f->buf_size =3D pending; >> > =20 >> > + if (f->shutdown) { >> > + return 0; >> > + } >>=20 >> I also wondered if perhaps an error would be reasonable here; but I'm >> not sure what a read(2) does after a shutdown(2). >>=20 >> Still, >>=20 >>=20 >> Reviewed-by: Dr. David Alan Gilbert > > Actually, it turns out this breaks an assumption - 'shutdown' must cause > reads/writes/etc to fail and for the qemu_file to go into error state. > There's a few places we loop doing IO until we either change migration > state or the file goes into error. > > > diff --git a/migration/qemu-file.c b/migration/qemu-file.c > index 1e5543a279..bbb2b63927 100644 > --- a/migration/qemu-file.c > +++ b/migration/qemu-file.c > @@ -63,11 +63,18 @@ struct QEMUFile { > */ > int qemu_file_shutdown(QEMUFile *f) > { > + int ret; > + > f->shutdown =3D true; > if (!f->ops->shut_down) { > return -ENOSYS; > } > - return f->ops->shut_down(f->opaque, true, true, NULL); > + ret =3D f->ops->shut_down(f->opaque, true, true, NULL); > + > + if (!f->last_error) { > + qemu_file_set_error(f, -EIO); > + } > + return ret; > } > =20 > /* > > > seems to fix it for me. will gve it a try later. Thanks.