Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752002AbdFUU36 (ORCPT ); Wed, 21 Jun 2017 16:29:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:33040 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751108AbdFUU35 (ORCPT ); Wed, 21 Jun 2017 16:29:57 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EAD6C2187C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=sstabellini@kernel.org Date: Wed, 21 Jun 2017 13:29:53 -0700 (PDT) From: Stefano Stabellini X-X-Sender: sstabellini@sstabellini-ThinkPad-X260 To: Boris Ostrovsky cc: Stefano Stabellini , xen-devel@lists.xen.org, linux-kernel@vger.kernel.org, jgross@suse.com, Stefano Stabellini Subject: Re: [PATCH v4 11/18] xen/pvcalls: implement accept command In-Reply-To: Message-ID: References: <1497553787-3709-1-git-send-email-sstabellini@kernel.org> <1497553787-3709-11-git-send-email-sstabellini@kernel.org> User-Agent: Alpine 2.10 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4107 Lines: 140 On Tue, 20 Jun 2017, Boris Ostrovsky wrote: > > static void __pvcalls_back_accept(struct work_struct *work) > > { > > + struct sockpass_mapping *mappass = container_of( > > + work, struct sockpass_mapping, register_work); > > + struct sock_mapping *map; > > + struct pvcalls_ioworker *iow; > > + struct pvcalls_fedata *fedata; > > + struct socket *sock; > > + struct xen_pvcalls_response *rsp; > > + struct xen_pvcalls_request *req; > > + int notify; > > + int ret = -EINVAL; > > + unsigned long flags; > > + > > + fedata = mappass->fedata; > > + /* > > + * __pvcalls_back_accept can race against pvcalls_back_accept. > > + * We only need to check the value of "cmd" on read. It could be > > + * done atomically, but to simplify the code on the write side, we > > + * use a spinlock. > > + */ > > + spin_lock_irqsave(&mappass->copy_lock, flags); > > + req = &mappass->reqcopy; > > + if (req->cmd != PVCALLS_ACCEPT) { > > + spin_unlock_irqrestore(&mappass->copy_lock, flags); > > + return; > > + } > > + spin_unlock_irqrestore(&mappass->copy_lock, flags); > > + > > + sock = sock_alloc(); > > + if (sock == NULL) > > + goto out_error; > > + sock->type = mappass->sock->type; > > + sock->ops = mappass->sock->ops; > > + > > + ret = inet_accept(mappass->sock, sock, O_NONBLOCK, true); > > + if (ret == -EAGAIN) { > > + sock_release(sock); > > + goto out_error; > > + } > > + > > + map = pvcalls_new_active_socket(fedata, > > + req->u.accept.id_new, > > + req->u.accept.ref, > > + req->u.accept.evtchn, > > + sock); > > + if (!map) { > > + sock_release(sock); > > + goto out_error; > > Again, lost ret value. Yep, I'll fix > > + } > > + > > + map->sockpass = mappass; > > + iow = &map->ioworker; > > + atomic_inc(&map->read); > > + atomic_inc(&map->io); > > + queue_work(iow->wq, &iow->register_work); > > + > > +out_error: > > + rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++); > > + rsp->req_id = req->req_id; > > + rsp->cmd = req->cmd; > > + rsp->u.accept.id = req->u.accept.id; > > + rsp->ret = ret; > > + RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&fedata->ring, notify); > > + if (notify) > > + notify_remote_via_irq(fedata->irq); > > + > > + mappass->reqcopy.cmd = 0; > > } > > > > static void pvcalls_pass_sk_data_ready(struct sock *sock) > > { > > + struct sockpass_mapping *mappass = sock->sk_user_data; > > + > > + if (mappass == NULL) > > + return; > > + > > + queue_work(mappass->wq, &mappass->register_work); > > } > > > > static int pvcalls_back_bind(struct xenbus_device *dev, > > @@ -383,6 +456,43 @@ static int pvcalls_back_listen(struct xenbus_device *dev, > > static int pvcalls_back_accept(struct xenbus_device *dev, > > struct xen_pvcalls_request *req) > > { > > + struct pvcalls_fedata *fedata; > > + struct sockpass_mapping *mappass; > > + int ret = -EINVAL; > > Unnecessary initialization. It is not unnecessary: if mappass is NULL few lines below, it will goto out_error without setting ret. > > + struct xen_pvcalls_response *rsp; > > + unsigned long flags; > > + > > + fedata = dev_get_drvdata(&dev->dev); > > + > > + mappass = radix_tree_lookup(&fedata->socketpass_mappings, > > + req->u.accept.id); > > + if (mappass == NULL) > > + goto out_error; > > + > > + /* > > + * Limitation of the current implementation: only support one > > + * concurrent accept or poll call on one socket. > > + */ > > + spin_lock_irqsave(&mappass->copy_lock, flags); > > + if (mappass->reqcopy.cmd != 0) { > > + spin_unlock_irqrestore(&mappass->copy_lock, flags); > > + ret = -EINTR; > > + goto out_error; > > + } > > + > > + mappass->reqcopy = *req; > > + spin_unlock_irqrestore(&mappass->copy_lock, flags); > > + queue_work(mappass->wq, &mappass->register_work); > > + > > + /* Tell the caller we don't need to send back a notification yet */ > > + return -1; > > + > > +out_error: > > + rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++); > > + rsp->req_id = req->req_id; > > + rsp->cmd = req->cmd; > > + rsp->u.accept.id = req->u.accept.id; > > + rsp->ret = ret; > > return 0; > > } > > >