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Tue, 4 Aug 2020 12:49:50 +0000 (UTC) Date: Tue, 4 Aug 2020 13:49:49 +0100 From: Stefan Hajnoczi To: Jagannathan Raman Subject: Re: [PATCH v8 06/20] multi-process: define MPQemuMsg format and transmission functions Message-ID: <20200804124949.GB1284674@stefanha-x1.localdomain> References: <50f84ecac23889920aeed397adb9317b8ea5a54b.1596217462.git.jag.raman@oracle.com> MIME-Version: 1.0 In-Reply-To: <50f84ecac23889920aeed397adb9317b8ea5a54b.1596217462.git.jag.raman@oracle.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="rJwd6BRFiFCcLxzm" Content-Disposition: inline Received-SPF: pass client-ip=207.211.31.81; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/04 01:01:15 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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: elena.ufimtseva@oracle.com, fam@euphon.net, swapnil.ingle@nutanix.com, john.g.johnson@oracle.com, qemu-devel@nongnu.org, kraxel@redhat.com, quintela@redhat.com, mst@redhat.com, armbru@redhat.com, kanth.ghatraju@oracle.com, felipe@nutanix.com, thuth@redhat.com, ehabkost@redhat.com, konrad.wilk@oracle.com, dgilbert@redhat.com, alex.williamson@redhat.com, thanos.makatos@nutanix.com, rth@twiddle.net, kwolf@redhat.com, berrange@redhat.com, mreitz@redhat.com, ross.lagerwall@citrix.com, marcandre.lureau@gmail.com, pbonzini@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --rJwd6BRFiFCcLxzm Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Fri, Jul 31, 2020 at 02:20:13PM -0400, Jagannathan Raman wrote: > +static int mpqemu_readv(QIOChannel *ioc, struct iovec *iov, int **fds, > + size_t *nfds, Error **errp) readv(2) and similar functions take an int iovcnt argument while mpqemu_readv() takes just a single struct iovec. The name mpqemu_read() seems more appopriate and iov argument could be replaced by void *buf, size_t len. That is cleaner because this function modifies the iov argument (callers need to be be careful!). > +{ > + struct iovec *l_iov = iov; > + size_t *l_nfds = nfds; > + unsigned int niov = 1; > + int **l_fds = fds; > + size_t size, len; > + Error *local_err = NULL; > + > + size = iov->iov_len; > + > + while (size > 0) { > + len = qio_channel_readv_full(ioc, l_iov, niov, l_fds, l_nfds, > + &local_err); > + > + if (len == QIO_CHANNEL_ERR_BLOCK) { > + if (qemu_in_coroutine()) { > + qio_channel_yield(ioc, G_IO_IN); > + } else { > + qio_channel_wait(ioc, G_IO_IN); > + } > + continue; > + } > + > + if (len <= 0) { size_t is unsigned so this does not detect negative values. Please use qio_channel_readv_full()'s return type (ssize_t) instead. > + error_propagate(errp, local_err); > + return -EIO; > + } > + > + l_fds = NULL; > + l_nfds = NULL; > + > + size -= len; > + > + (void)iov_discard_front(&l_iov, &niov, len); > + } > + > + return iov->iov_len; read()-style functions return the number of bytes read. mpqemu_readv() returns the number of unread bytes remaining. Maintaining consistency with read() function conventions will reduce the chance of bugs, so I suggest returning the number of bytes read instead. > +} > + > +void mpqemu_msg_recv(MPQemuMsg *msg, QIOChannel *ioc, Error **errp) > +{ > + Error *local_err = NULL; > + int *fds = NULL; > + struct iovec hdr, data; > + size_t nfds = 0; > + > + hdr.iov_base = msg; > + hdr.iov_len = MPQEMU_MSG_HDR_SIZE; > + > + if (mpqemu_readv(ioc, &hdr, &fds, &nfds, &local_err) < 0) { > + error_propagate(errp, local_err); > + return; > + } Can we read less than MPQEMU_MSG_HDR_SIZE if the peer closes the socket? That case probably needs to be handled. > +void mpqemu_msg_cleanup(MPQemuMsg *msg) > +{ > + if (msg->data2) { > + free(msg->data2); The buffer was allocated with g_malloc0() so g_free() should be used to free it. --rJwd6BRFiFCcLxzm Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAl8pWW0ACgkQnKSrs4Gr c8jxYQf/ZcOxxZC9olljiHU+zLeRrF5KS5Ntn5e4JxJzFMcBXzgVpvWZVEIWleW9 24s9KaiGv3m4Ge28AKzQh4YadIT++uwfEFeI2kvvn95As2KGimzCb5rLM6B7KwRJ 0emMaS0ivmQnbHpmIKlpckg9x7Kle2ti+p10kVkg/SkrayNfs/T0vK9ylQDZ9cwC 8gMCcu2aJZp6tT2ydphRRlyoGNEnbaQel2B9MGVV/8TpclAmFNCjuVMJhzP2VOfN L5ckbsCzIwgxQY13R8WEHU1jgc3GXvqsM4DGBKqP5KRRKiuhDodG/rlsVQSSbQsZ 3/3G5qxG7iYnMvfPZS7B1D48gme4Jg== =x3oI -----END PGP SIGNATURE----- --rJwd6BRFiFCcLxzm--