From patchwork Thu Nov 2 17:19:56 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Sebastian Andrzej Siewior X-Patchwork-Id: 10039051 X-Patchwork-Delegate: bhelgaas@google.com Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id E7791600C5 for ; Thu, 2 Nov 2017 17:20:04 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id CA9CD28C8F for ; Thu, 2 Nov 2017 17:20:04 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id BCF8B291CC; Thu, 2 Nov 2017 17:20:04 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id F330328C8F for ; Thu, 2 Nov 2017 17:19:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754205AbdKBRT6 convert rfc822-to-8bit (ORCPT ); Thu, 2 Nov 2017 13:19:58 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:55516 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751587AbdKBRT5 (ORCPT ); Thu, 2 Nov 2017 13:19:57 -0400 Received: from bigeasy by Galois.linutronix.de with local (Exim 4.80) (envelope-from ) id 1eAJ9O-0002cK-0X; Thu, 02 Nov 2017 18:19:30 +0100 Date: Thu, 2 Nov 2017 18:19:56 +0100 From: Sebastian Andrzej Siewior To: Logan Gunthorpe Cc: linux-pci@vger.kernel.org, tglx@linutronix.de, Kurt Schwemmer Subject: [PATCH v3] pci/switchtec: Don't use completion's wait queue Message-ID: <20171102171955.lvnvqnwl4qwhlmdk@linutronix.de> References: <20171004095007.19148-1-bigeasy@linutronix.de> <20171005105100.2nf4ih2fgq6dax5g@linutronix.de> <0ae3975a-b1b1-fb8b-2f90-ff103da9d178@deltatee.com> <20171102150729.5hylh6yjpqyqurnk@linutronix.de> <7f4a4474-bea2-f6b0-037e-2f487cc3d6cd@deltatee.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <7f4a4474-bea2-f6b0-037e-2f487cc3d6cd@deltatee.com> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The poll callback is using completion's wait_queue_head_t member and puts it in poll_wait() so the poll() caller gets a wakeup after command completed. This does not work on RT because we don't have a wait_queue_head_t in our completion implementation. Nobody in tree does like that in tree so this is the only driver that breaks. Instead of using the completion here is waitqueue with a status flag as suggested by Logan. I don't have the HW so I have no idea if it works as expected, so please test it. Cc: Kurt Schwemmer Cc: Logan Gunthorpe Signed-off-by: Sebastian Andrzej Siewior --- v2…v3: add a READ_ONCE while accessing ->cmd_done drivers/pci/switch/switchtec.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) --- a/drivers/pci/switch/switchtec.c +++ b/drivers/pci/switch/switchtec.c @@ -306,10 +306,11 @@ struct switchtec_user { enum mrpc_state state; - struct completion comp; + wait_queue_head_t cmd_comp; struct kref kref; struct list_head list; + bool cmd_done; u32 cmd; u32 status; u32 return_code; @@ -331,7 +332,7 @@ static struct switchtec_user *stuser_cre stuser->stdev = stdev; kref_init(&stuser->kref); INIT_LIST_HEAD(&stuser->list); - init_completion(&stuser->comp); + init_waitqueue_head(&stuser->cmd_comp); stuser->event_cnt = atomic_read(&stdev->event_cnt); dev_dbg(&stdev->dev, "%s: %p\n", __func__, stuser); @@ -414,7 +415,7 @@ static int mrpc_queue_cmd(struct switcht kref_get(&stuser->kref); stuser->read_len = sizeof(stuser->data); stuser_set_state(stuser, MRPC_QUEUED); - init_completion(&stuser->comp); + stuser->cmd_done = false; list_add_tail(&stuser->list, &stdev->mrpc_queue); mrpc_cmd_submit(stdev); @@ -451,7 +452,8 @@ static void mrpc_complete_cmd(struct swi stuser->read_len); out: - complete_all(&stuser->comp); + stuser->cmd_done = true; + wake_up_interruptible(&stuser->cmd_comp); list_del_init(&stuser->list); stuser_put(stuser); stdev->mrpc_busy = 0; @@ -721,10 +723,11 @@ static ssize_t switchtec_dev_read(struct mutex_unlock(&stdev->mrpc_mutex); if (filp->f_flags & O_NONBLOCK) { - if (!try_wait_for_completion(&stuser->comp)) + if (!READ_ONCE(stuser->cmd_done)) return -EAGAIN; } else { - rc = wait_for_completion_interruptible(&stuser->comp); + rc = wait_event_interruptible(stuser->cmd_comp, + stuser->cmd_done); if (rc < 0) return rc; } @@ -772,7 +775,7 @@ static unsigned int switchtec_dev_poll(s struct switchtec_dev *stdev = stuser->stdev; int ret = 0; - poll_wait(filp, &stuser->comp.wait, wait); + poll_wait(filp, &stuser->cmd_comp, wait); poll_wait(filp, &stdev->event_wq, wait); if (lock_mutex_and_test_alive(stdev)) @@ -780,7 +783,7 @@ static unsigned int switchtec_dev_poll(s mutex_unlock(&stdev->mrpc_mutex); - if (try_wait_for_completion(&stuser->comp)) + if (READ_ONCE(stuser->cmd_done)) ret |= POLLIN | POLLRDNORM; if (stuser->event_cnt != atomic_read(&stdev->event_cnt)) @@ -1255,7 +1258,8 @@ static void stdev_kill(struct switchtec_ /* Wake up and kill any users waiting on an MRPC request */ list_for_each_entry_safe(stuser, tmpuser, &stdev->mrpc_queue, list) { - complete_all(&stuser->comp); + stuser->cmd_done = true; + wake_up_interruptible(&stuser->cmd_comp); list_del_init(&stuser->list); stuser_put(stuser); }