From patchwork Mon Sep 23 13:58:39 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bill Kuzeja X-Patchwork-Id: 11156989 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4D95414DB for ; Mon, 23 Sep 2019 13:58:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 35C692168B for ; Mon, 23 Sep 2019 13:58:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2408331AbfIWN6p convert rfc822-to-8bit (ORCPT ); Mon, 23 Sep 2019 09:58:45 -0400 Received: from us-smtp-delivery-131.mimecast.com ([63.128.21.131]:51799 "EHLO us-smtp-delivery-131.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2406362AbfIWN6p (ORCPT ); Mon, 23 Sep 2019 09:58:45 -0400 Received: from mailhub5.stratus.com (134.111.1.18 [134.111.1.18]) by relay.mimecast.com with ESMTP id us-mta-72-V2PPOjCePjOdd4e-xM_m3w-1; Mon, 23 Sep 2019 09:58:40 -0400 Received: from EXHQ1.corp.stratus.com (exhq1.corp.stratus.com [134.111.200.125]) by mailhub5.stratus.com (8.12.11/8.12.11) with ESMTP id x8NDwdnB029381; Mon, 23 Sep 2019 09:58:40 -0400 Received: from linuxdev.lnx.eng.stratus.com (134.111.220.63) by EXHQ1.corp.stratus.com (134.111.200.125) with Microsoft SMTP Server (TLS) id 14.3.279.2; Mon, 23 Sep 2019 09:58:34 -0400 From: Bill Kuzeja To: , , , Subject: [PATCH v2] xhci: Prevent deadlock when xhci adapter breaks during init Date: Mon, 23 Sep 2019 09:58:39 -0400 Message-ID: <1569247119-32708-1-git-send-email-William.Kuzeja@stratus.com> X-Mailer: git-send-email 1.8.3.1 MIME-Version: 1.0 X-MC-Unique: V2PPOjCePjOdd4e-xM_m3w-1 X-Mimecast-Spam-Score: 0 Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org The system can hit a deadlock if an xhci adapter breaks while initializing. The deadlock is between two threads: thread 1 is tearing down the adapter and is stuck in usb_unlocked_disable_lpm waiting to lock the hcd->handwidth_mutex. Thread 2 is holding this mutex (while still trying to add a usb device), but is stuck in xhci_endpoint_reset waiting for a stop or config command to complete. A reboot is required to resolve. It turns out when calling xhci_queue_stop_endpoint and xhci_queue_configure_endpoint in xhci_endpoint_reset, the return code is not checked for errors. If the timing is right and the adapter dies just before either of these commands get issued, we hang indefinitely waiting for a completion on a command that didn't get issued. This wasn't a problem before the following fix because we didn't send commands in xhci_endpoint_reset: commit f5249461b504 ("xhci: Clear the host side toggle manually when endpoint is soft reset") With the patch I am submitting, a duration test which breaks adapters during initialization (and which deadlocks with the standard kernel) runs without issue. Fixes: f5249461b504 ("xhci: Clear the host side toggle manually when endpoint is soft reset") Cc: Mathias Nyman Cc: Torez Smith Signed-off-by: Bill Kuzeja Signed-off-by: Torez Smith --- drivers/usb/host/xhci.c | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-) diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c index 5008659..ed44ec2 100644 --- a/drivers/usb/host/xhci.c +++ b/drivers/usb/host/xhci.c @@ -3083,6 +3083,7 @@ static void xhci_endpoint_reset(struct usb_hcd *hcd, unsigned int ep_index; unsigned long flags; u32 ep_flag; + int err; xhci = hcd_to_xhci(hcd); if (!host_ep->hcpriv) @@ -3142,7 +3143,17 @@ static void xhci_endpoint_reset(struct usb_hcd *hcd, xhci_free_command(xhci, cfg_cmd); goto cleanup; } - xhci_queue_stop_endpoint(xhci, stop_cmd, udev->slot_id, ep_index, 0); + + err = xhci_queue_stop_endpoint(xhci, stop_cmd, udev->slot_id, + ep_index, 0); + if (err < 0) { + spin_unlock_irqrestore(&xhci->lock, flags); + xhci_free_command(xhci, cfg_cmd); + xhci_dbg(xhci, "%s: Failed to queue stop ep command, %d ", + __func__, err); + goto cleanup; + } + xhci_ring_cmd_db(xhci); spin_unlock_irqrestore(&xhci->lock, flags); @@ -3156,8 +3167,16 @@ static void xhci_endpoint_reset(struct usb_hcd *hcd, ctrl_ctx, ep_flag, ep_flag); xhci_endpoint_copy(xhci, cfg_cmd->in_ctx, vdev->out_ctx, ep_index); - xhci_queue_configure_endpoint(xhci, cfg_cmd, cfg_cmd->in_ctx->dma, + err = xhci_queue_configure_endpoint(xhci, cfg_cmd, cfg_cmd->in_ctx->dma, udev->slot_id, false); + if (err < 0) { + spin_unlock_irqrestore(&xhci->lock, flags); + xhci_free_command(xhci, cfg_cmd); + xhci_dbg(xhci, "%s: Failed to queue config ep command, %d ", + __func__, err); + goto cleanup; + } + xhci_ring_cmd_db(xhci); spin_unlock_irqrestore(&xhci->lock, flags);