Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752444AbdCHXLl (ORCPT ); Wed, 8 Mar 2017 18:11:41 -0500 Received: from bh-25.webhostbox.net ([208.91.199.152]:50109 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750727AbdCHXLk (ORCPT ); Wed, 8 Mar 2017 18:11:40 -0500 From: Guenter Roeck To: Greg Kroah-Hartman Cc: Douglas Anderson , Brian Norris , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, Guenter Roeck Subject: [PATCH] usb: hub: Fix error loop seen after hub communication errors Date: Wed, 8 Mar 2017 13:08:49 -0800 Message-Id: <1489007329-8352-1-git-send-email-linux@roeck-us.net> X-Mailer: git-send-email 2.7.4 X-Authenticated_sender: guenter@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: authenticated_id: guenter@roeck-us.net X-Authenticated-Sender: bh-25.webhostbox.net: guenter@roeck-us.net X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3482 Lines: 84 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 -> ... To break the loop, only trigger the hub event queue if communication with the hub is successful. Signed-off-by: Guenter Roeck --- drivers/usb/core/hub.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index 5286bf67869a..f22ab428b310 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -1197,7 +1197,8 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type) &hub->leds, LED_CYCLE_PERIOD); /* Scan all ports that need attention */ - kick_hub_wq(hub); + if (!status) + kick_hub_wq(hub); if (type == HUB_INIT2 || type == HUB_INIT3) { /* Allow autosuspend if it was suppressed */ -- 2.7.4