Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935543AbdCJNtb (ORCPT ); Fri, 10 Mar 2017 08:49:31 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:42817 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934259AbdCJLwU (ORCPT ); Fri, 10 Mar 2017 06:52:20 -0500 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, "Greg Kroah-Hartman" , "Mathias Nyman" , "Lu Baolu" Date: Fri, 10 Mar 2017 11:46:22 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 153/370] usb: xhci: hold lock over xhci_abort_cmd_ring() 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: 2313 Lines: 63 3.16.42-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Lu Baolu commit 4dea70778c0f48b4385c7720c363ec8d37a401b4 upstream. In command timer function, xhci_handle_command_timeout(), xhci->lock is unlocked before call into xhci_abort_cmd_ring(). This might cause race between the timer function and the event handler. The xhci_abort_cmd_ring() function sets the CMD_RING_ABORT bit in the command register and polling it until the setting takes effect. A stop command ring event might be handled between writing the abort bit and polling for it. The event handler will restart the command ring, which causes the failure of polling, and we ever believed that we failed to stop it. As a bonus, this also fixes some issues of calling functions without locking in xhci_handle_command_timeout(). Signed-off-by: Lu Baolu Signed-off-by: Mathias Nyman Signed-off-by: Greg Kroah-Hartman [bwh: Backported to 3.16: drop changes to the "failed to restart, or host removed" case] Signed-off-by: Ben Hutchings --- drivers/usb/host/xhci-ring.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -1311,21 +1311,25 @@ void xhci_handle_command_timeout(unsigne hw_ring_state = xhci_read_64(xhci, &xhci->op_regs->cmd_ring); if ((xhci->cmd_ring_state & CMD_RING_STATE_RUNNING) && (hw_ring_state & CMD_RING_RUNNING)) { - - spin_unlock_irqrestore(&xhci->lock, flags); xhci_dbg(xhci, "Command timeout\n"); ret = xhci_abort_cmd_ring(xhci); if (unlikely(ret == -ESHUTDOWN)) { xhci_err(xhci, "Abort command ring failed\n"); xhci_cleanup_command_queue(xhci); + spin_unlock_irqrestore(&xhci->lock, flags); usb_hc_died(xhci_to_hcd(xhci)->primary_hcd); xhci_dbg(xhci, "xHCI host controller is dead.\n"); + + return; } - return; + + goto time_out_completed; } /* command timeout on stopped ring, ring can't be aborted */ xhci_dbg(xhci, "Command timeout on stopped ring\n"); xhci_handle_stopped_cmd_ring(xhci, xhci->current_cmd); + +time_out_completed: spin_unlock_irqrestore(&xhci->lock, flags); return; }