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Wed, 8 Jan 2020 09:49:47 +0000 (UTC) Received: from work-vm (unknown [10.36.118.12]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 89C6B5F700; Wed, 8 Jan 2020 09:49:46 +0000 (UTC) Date: Wed, 8 Jan 2020 09:49:44 +0000 From: "Dr. David Alan Gilbert" To: Juan Quintela Subject: Re: [PATCH 1/4] qemu-file: Don't do IO after shutdown Message-ID: <20200108094944.GA3184@work-vm> References: <20191218050439.5989-1-quintela@redhat.com> <20191218050439.5989-2-quintela@redhat.com> <20191218122702.GF3707@work-vm> MIME-Version: 1.0 In-Reply-To: <20191218122702.GF3707@work-vm> User-Agent: Mutt/1.13.0 (2019-11-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-MC-Unique: _pSL_fgKMFOIR3BQj-ipUw-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Content-Disposition: inline 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: , 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 (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. Dave > > len =3D f->ops->get_buffer(f->opaque, f->buf + pending, f->pos, > > IO_BUF_SIZE - pending, &local_error); > > if (len > 0) { > > @@ -642,6 +652,9 @@ int64_t qemu_ftell(QEMUFile *f) > > =20 > > int qemu_file_rate_limit(QEMUFile *f) > > { > > + if (f->shutdown) { > > + return 1; > > + } > > if (qemu_file_get_error(f)) { > > return 1; > > } > > --=20 > > 2.23.0 > >=20 > -- > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK >=20 >=20 -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK