Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753115AbdHROAw (ORCPT ); Fri, 18 Aug 2017 10:00:52 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:55245 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752314AbdHRNPm (ORCPT ); Fri, 18 Aug 2017 09:15:42 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Alan Stern" , "Guenter Roeck" , "Greg Kroah-Hartman" Date: Fri, 18 Aug 2017 14:13:20 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 012/134] usb: hub: Fix error loop seen after hub communication errors In-Reply-To: X-SA-Exim-Connect-IP: 82.70.136.246 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5018 Lines: 137 3.16.47-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Guenter Roeck commit 245b2eecee2aac6fdc77dcafaa73c33f9644c3c7 upstream. While stress testing a usb controller using a bind/unbind looop, the following error loop was observed. usb 7-1.2: new low-speed USB device number 3 using xhci-hcd usb 7-1.2: hub failed to enable device, error -108 usb 7-1-port2: cannot disable (err = -22) usb 7-1-port2: couldn't allocate usb_device usb 7-1-port2: cannot disable (err = -22) hub 7-1:1.0: hub_ext_port_status failed (err = -22) hub 7-1:1.0: hub_ext_port_status failed (err = -22) hub 7-1:1.0: activate --> -22 hub 7-1:1.0: hub_ext_port_status failed (err = -22) hub 7-1:1.0: hub_ext_port_status failed (err = -22) hub 7-1:1.0: activate --> -22 hub 7-1:1.0: hub_ext_port_status failed (err = -22) hub 7-1:1.0: hub_ext_port_status failed (err = -22) hub 7-1:1.0: activate --> -22 hub 7-1:1.0: hub_ext_port_status failed (err = -22) hub 7-1:1.0: hub_ext_port_status failed (err = -22) hub 7-1:1.0: activate --> -22 hub 7-1:1.0: hub_ext_port_status failed (err = -22) hub 7-1:1.0: hub_ext_port_status failed (err = -22) hub 7-1:1.0: activate --> -22 hub 7-1:1.0: hub_ext_port_status failed (err = -22) hub 7-1:1.0: hub_ext_port_status failed (err = -22) hub 7-1:1.0: activate --> -22 hub 7-1:1.0: hub_ext_port_status failed (err = -22) hub 7-1:1.0: hub_ext_port_status failed (err = -22) hub 7-1:1.0: activate --> -22 hub 7-1:1.0: hub_ext_port_status failed (err = -22) hub 7-1:1.0: hub_ext_port_status failed (err = -22) hub 7-1:1.0: activate --> -22 hub 7-1:1.0: hub_ext_port_status failed (err = -22) hub 7-1:1.0: hub_ext_port_status failed (err = -22) ** 57 printk messages dropped ** hub 7-1:1.0: activate --> -22 ** 82 printk messages dropped ** hub 7-1:1.0: hub_ext_port_status failed (err = -22) This continues forever. After adding tracebacks into the code, the call sequence leading to this is found to be as follows. [] hub_activate+0x368/0x7b8 [] hub_resume+0x2c/0x3c [] usb_resume_interface.isra.6+0x128/0x158 [] usb_suspend_both+0x1e8/0x288 [] usb_runtime_suspend+0x3c/0x98 [] __rpm_callback+0x48/0x7c [] rpm_callback+0xa8/0xd4 [] rpm_suspend+0x84/0x758 [] rpm_idle+0x2c8/0x498 [] __pm_runtime_idle+0x60/0xac [] usb_autopm_put_interface+0x6c/0x7c [] hub_event+0x10ac/0x12ac [] process_one_work+0x390/0x6b8 [] worker_thread+0x480/0x610 [] kthread+0x164/0x178 [] ret_from_fork+0x10/0x40 kick_hub_wq() is called from hub_activate() even after failures to communicate with the hub. This results in an endless sequence of hub event -> hub activate -> wq trigger -> hub event -> ... Provide two solutions for the problem. - Only trigger the hub event queue if communication with the hub is successful. - After a suspend failure, only resume already suspended interfaces if the communication with the device is still possible. Each of the changes fixes the observed problem. Use both to improve robustness. Acked-by: Alan Stern Signed-off-by: Guenter Roeck Signed-off-by: Greg Kroah-Hartman [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- drivers/usb/core/driver.c | 18 ++++++++++++++++++ drivers/usb/core/hub.c | 5 ++++- 2 files changed, 22 insertions(+), 1 deletion(-) --- a/drivers/usb/core/driver.c +++ b/drivers/usb/core/driver.c @@ -1331,6 +1331,24 @@ static int usb_suspend_both(struct usb_d */ if (udev->parent && !PMSG_IS_AUTO(msg)) status = 0; + + /* + * If the device is inaccessible, don't try to resume + * suspended interfaces and just return the error. + */ + if (status && status != -EBUSY) { + int err; + u16 devstat; + + err = usb_get_status(udev, USB_RECIP_DEVICE, 0, + &devstat); + if (err) { + dev_err(&udev->dev, + "Failed to suspend device, error %d\n", + status); + goto done; + } + } } /* If the suspend failed, resume interfaces that did get suspended */ --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -1044,6 +1044,9 @@ static void hub_activate(struct usb_hub portstatus = portchange = 0; status = hub_port_status(hub, port1, &portstatus, &portchange); + if (status) + goto abort; + if (udev || (portstatus & USB_PORT_STAT_CONNECTION)) dev_dbg(&port_dev->dev, "status %04x change %04x\n", portstatus, portchange); @@ -1176,7 +1179,7 @@ static void hub_activate(struct usb_hub /* Scan all ports that need attention */ kick_khubd(hub); - + abort: /* Allow autosuspend if it was suppressed */ if (type <= HUB_INIT3) usb_autopm_put_interface_async(to_usb_interface(hub->intfdev));