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Sun, 29 Dec 2019 18:20:19 +0000 (UTC) Received: from redhat.com (ovpn-116-53.ams2.redhat.com [10.36.116.53]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E7E7460CC0; Sun, 29 Dec 2019 18:20:18 +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: <20191218122702.GF3707@work-vm> (David Alan Gilbert's message of "Wed, 18 Dec 2019 12:27:02 +0000") References: <20191218050439.5989-1-quintela@redhat.com> <20191218050439.5989-2-quintela@redhat.com> <20191218122702.GF3707@work-vm> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) Date: Sun, 29 Dec 2019 19:20:11 +0100 Message-ID: <87png7kn8k.fsf@trasno.org> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-MC-Unique: q02aJ6INNc2xzMScXvc6Qg-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: > * 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; >> + } > > OK, I did wonder if you need to free the iovec. We need to improve things here. We should free it on the 1st error/shutdown. Withought fixing all callers, I don't feel "safe" doing it. > >> 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; >> + } > > 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). We should check this sooner. Same than prevoious. If there has been an error anywhere else, we should fail qemu_fill_buffer(). Right now we don't do it. and we should. qemu_get_error() and the setter should dissapear. And we should just return errors in all functions. Especially now that we have migration thread, and we don't have callbacks anymore. > Still, > > > Reviewed-by: Dr. David Alan Gilbert Thanks, Juan. >> 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