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Tue, 28 Sep 2021 15:45:26 -0700 (PDT) Received: from t490s ([2607:fea8:56a2:9100::d3ec]) by smtp.gmail.com with ESMTPSA id b14sm229702ilc.63.2021.09.28.15.45.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Sep 2021 15:45:26 -0700 (PDT) Date: Tue, 28 Sep 2021 18:45:24 -0400 From: Peter Xu To: Leonardo Bras Subject: Re: [PATCH v3 2/3] QIOChannelSocket: Implement io_async_write & io_async_flush Message-ID: References: <20210922222423.644444-1-leobras@redhat.com> <20210922222423.644444-3-leobras@redhat.com> MIME-Version: 1.0 In-Reply-To: <20210922222423.644444-3-leobras@redhat.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=peterx@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, 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: qemu-devel@nongnu.org, Jason Wang , Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= , "Dr. David Alan Gilbert" , Juan Quintela Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Sep 22, 2021 at 07:24:22PM -0300, Leonardo Bras wrote: > +static void qio_channel_socket_async_flush(QIOChannel *ioc, > + Error **errp) > +{ > + QIOChannelSocket *sioc = QIO_CHANNEL_SOCKET(ioc); > + struct msghdr msg = {}; > + struct pollfd pfd; > + struct sock_extended_err *serr; > + struct cmsghdr *cm; > + char control[CMSG_SPACE(sizeof(int) * SOCKET_MAX_FDS)]; > + int ret; > + > + memset(control, 0, CMSG_SPACE(sizeof(int) * SOCKET_MAX_FDS)); > + msg.msg_control = control; > + msg.msg_controllen = sizeof(control); > + > + while (sioc->async_sent < sioc->async_queued) { > + ret = recvmsg(sioc->fd, &msg, MSG_ERRQUEUE); > + if (ret < 0) { > + if (errno == EAGAIN) { > + /* Nothing on errqueue, wait */ > + pfd.fd = sioc->fd; > + pfd.events = 0; > + ret = poll(&pfd, 1, 250); > + if (ret == 0) { > + /* > + * Timeout : After 250ms without receiving any zerocopy > + * notification, consider all data as sent. > + */ > + break; After a timeout, we'll break the while loop and continue parsing an invalid msg [1]. Is that what we want? Also, I don't think we can return the flush() even if timed out - iiuc we should keep polling until we have async_sent==async_queued. It depends on how we define flush(): if it's "when this function returns all data is sent", then we should keep polling, and afaict this is what we want here right now. > + } else if (ret < 0 || > + (pfd.revents & (POLLERR | POLLHUP | POLLNVAL))) { > + error_setg_errno(errp, errno, > + "Poll error"); > + break; > + } else { > + continue; > + } > + } > + if (errno == EINTR) { > + continue; > + } > + > + error_setg_errno(errp, errno, > + "Unable to read errqueue"); > + break; > + } > + > + cm = CMSG_FIRSTHDR(&msg); [1] > + if (cm->cmsg_level != SOL_IP && > + cm->cmsg_type != IP_RECVERR) { > + error_setg_errno(errp, EPROTOTYPE, > + "Wrong cmsg in errqueue"); > + break; > + } -- Peter Xu