Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758851Ab3GaCwd (ORCPT ); Tue, 30 Jul 2013 22:52:33 -0400 Received: from mail-pb0-f47.google.com ([209.85.160.47]:61736 "EHLO mail-pb0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751600Ab3GaCwb (ORCPT ); Tue, 30 Jul 2013 22:52:31 -0400 From: Julius Werner To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, Alan Stern , Sarah Sharp , Vincent Palatin , Benson Leung , Julius Werner Subject: [PATCH v2] usb: core: don't try to reset_device() a port that got just disconnected Date: Tue, 30 Jul 2013 19:51:20 -0700 Message-Id: <1375239080-21322-1-git-send-email-jwerner@chromium.org> X-Mailer: git-send-email 1.8.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2279 Lines: 58 The USB hub driver's event handler contains a check to catch SuperSpeed devices that transitioned into the SS.Inactive state and tries to fix them with a reset. It decides whether to do a plain hub port reset or call the usb_reset_device() function based on whether there was a device attached to the port. However, there are device/hub combinations (found with a JetFlash Transcend mass storage stick (8564:1000) on the root hub of an Intel LynxPoint PCH) which can transition to the SS.Inactive state on disconnect (and stay there long enough for the host to notice). In this case, above-mentioned reset check will call usb_reset_device() on the stale device data structure. The kernel will send pointless LPM control messages to the no longer connected device address and can even cause several 5 second khubd stalls on some (buggy?) host controllers, before finally accepting the device's fate amongst a flurry of error messages. This patch makes the choice of reset dependent on the port status that has just been read from the hub in addition to the existence of an in-kernel data structure for the device, and only proceeds with the more extensive reset if both are valid. Signed-off-by: Julius Werner --- drivers/usb/core/hub.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index 4a8a1d6..558313d 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -4798,7 +4798,8 @@ static void hub_events(void) hub->ports[i - 1]->child; dev_dbg(hub_dev, "warm reset port %d\n", i); - if (!udev) { + if (!udev || !(portstatus & + USB_PORT_STAT_CONNECTION)) { status = hub_port_reset(hub, i, NULL, HUB_BH_RESET_TIME, true); @@ -4808,8 +4809,8 @@ static void hub_events(void) usb_lock_device(udev); status = usb_reset_device(udev); usb_unlock_device(udev); + connect_change = 0; } - connect_change = 0; } if (connect_change) -- 1.7.12.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/