From patchwork Wed Oct 28 20:31:24 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mathias Nyman X-Patchwork-Id: 311160 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 32F78C55179 for ; Thu, 29 Oct 2020 02:45:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E18A52076B for ; Thu, 29 Oct 2020 02:45:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726085AbgJ1Vda (ORCPT ); Wed, 28 Oct 2020 17:33:30 -0400 Received: from mga03.intel.com ([134.134.136.65]:44643 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726025AbgJ1VdT (ORCPT ); Wed, 28 Oct 2020 17:33:19 -0400 IronPort-SDR: q7iquxM/ondJh42HI3aA42p4TxoMCWn74xZ2OjpQibp0R+Bq29dDE80LDUeuhLTFCUCPoCfujb QszYg0aEFZ9Q== X-IronPort-AV: E=McAfee;i="6000,8403,9788"; a="168432581" X-IronPort-AV: E=Sophos;i="5.77,428,1596524400"; d="scan'208";a="168432581" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Oct 2020 13:30:08 -0700 IronPort-SDR: rO3kI377EHDBcOhlUBqeSJDQbQTsStpR+rzc6r+365XZ5H/OKoIxf+36GFSl5FxlvQU+X5XdUJ vqhmivUJMx9Q== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.77,428,1596524400"; d="scan'208";a="323467833" Received: from mattu-haswell.fi.intel.com ([10.237.72.170]) by orsmga006.jf.intel.com with ESMTP; 28 Oct 2020 13:30:07 -0700 From: Mathias Nyman To: Cc: , Mathias Nyman , Hans de Goede , Mike Galbraith , Li Jun Subject: [PATCH 3/3] xhci: Don't create stream debugfs files with spinlock held. Date: Wed, 28 Oct 2020 22:31:24 +0200 Message-Id: <20201028203124.375344-4-mathias.nyman@linux.intel.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20201028203124.375344-1-mathias.nyman@linux.intel.com> References: <20201028203124.375344-1-mathias.nyman@linux.intel.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org Creating debugfs files while loding the spin_lock_irqsave(xhci->lock) creates a lock dependecy that could possibly deadlock. Lockdep warns: ===================================================== WARNING: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected 5.10.0-rc1pdx86+ #8 Not tainted ----------------------------------------------------- systemd-udevd/386 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire: ffffffffb1a94038 (pin_fs_lock){+.+.}-{2:2}, at: simple_pin_fs+0x22/0xa0 and this task is already holding: ffff9e7b87fbc430 (&xhci->lock){-.-.}-{2:2}, at: xhci_alloc_streams+0x5f9/0x810 which would create a new lock dependency: (&xhci->lock){-.-.}-{2:2} -> (pin_fs_lock){+.+.}-{2:2} Create the files a bit later after lock is released. Reported-by: Hans de Goede Reported-by: Mike Galbraith Tested-by: Hans de Goede CC: Li Jun Fixes: 673d74683627 ("usb: xhci: add debugfs support for ep with stream") Signed-off-by: Mathias Nyman --- drivers/usb/host/xhci.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c index 482fe8c5e3b4..d4a8d0efbbc4 100644 --- a/drivers/usb/host/xhci.c +++ b/drivers/usb/host/xhci.c @@ -3533,11 +3533,14 @@ static int xhci_alloc_streams(struct usb_hcd *hcd, struct usb_device *udev, xhci_dbg(xhci, "Slot %u ep ctx %u now has streams.\n", udev->slot_id, ep_index); vdev->eps[ep_index].ep_state |= EP_HAS_STREAMS; - xhci_debugfs_create_stream_files(xhci, vdev, ep_index); } xhci_free_command(xhci, config_cmd); spin_unlock_irqrestore(&xhci->lock, flags); + for (i = 0; i < num_eps; i++) { + ep_index = xhci_get_endpoint_index(&eps[i]->desc); + xhci_debugfs_create_stream_files(xhci, vdev, ep_index); + } /* Subtract 1 for stream 0, which drivers can't use */ return num_streams - 1;