From mboxrd@z Thu Jan 1 00:00:00 1970 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=-8.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 CE196C43381 for ; Wed, 27 Feb 2019 22:19:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9894C2133D for ; Wed, 27 Feb 2019 22:19:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="QmNwv1T8" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730269AbfB0WTW (ORCPT ); Wed, 27 Feb 2019 17:19:22 -0500 Received: from mail-it1-f194.google.com ([209.85.166.194]:54998 "EHLO mail-it1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729825AbfB0WTV (ORCPT ); Wed, 27 Feb 2019 17:19:21 -0500 Received: by mail-it1-f194.google.com with SMTP id w18so11756067itj.4 for ; Wed, 27 Feb 2019 14:19:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=9H1l5Wdj1GWuKsEb4xNzSrNS9tB+LdMfzHBMpMzE48A=; b=QmNwv1T8AuLJaC/OXX05TWwgaBQeqHtWCR+72Tp5tU5Fdtxk+u1J88m+vW4O474Vjq nmCMCZK7dyF9TOSxDDBufD6GBiIBLdqkLLKp1sQ8CDlvEWdKxskozmoCjd/6OYwTTHn4 PC0/SxcqNJD3yy5DoUgbLv+EbjNVy8IA9qLek= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=9H1l5Wdj1GWuKsEb4xNzSrNS9tB+LdMfzHBMpMzE48A=; b=UxC6qrSiqfshyB4SORmyBe+G3xR/HWVvpzVJgLIy5GQrYZJ4rboNI+r0hMSIrE+K4b YxysVGhtSM2yEBplfHYSJSJ4Qk75RVm02prSgLP3Fe/vQWxPl6XWQQgEEMTC5NYdS7vq SN+aVJkzOnB1freLIfktvMlzotgi/GW3DQWJbgejWhvbzebHUzl7c3/10pWe+CTpHw56 R6uvRIpYy3pj54O+boN4d9L7iLgT3m4J9PSISPD1wNFqX4GnWh9RtaUheKDS8GHwgrXO ew1lX7Q7jgIzmSM7NOkrA/D9OMFmjaAYSCoGWatBZn2Jr9vjD7CyjkjhvbaSU1zxLDr5 4l3w== X-Gm-Message-State: APjAAAX1ZZ13jdse/9GqITzGw70qcEHGZu1k4oB4yCr+WeNu9mgEHno1 tW6IyNrsSdiiDjDKrEj4hLKPCA== X-Google-Smtp-Source: APXvYqzlBsBEVWWoISsS63dRohR/pC3fhAMWhce+XLOLVStAodHvLeqa7uG/A+22gWY9D0r7tbvabQ== X-Received: by 2002:a24:9d94:: with SMTP id f142mr1065663itd.9.1551305960716; Wed, 27 Feb 2019 14:19:20 -0800 (PST) Received: from djkurtz2.bld.corp.google.com ([2620:15c:183:0:1cfd:61a5:7215:5f9c]) by smtp.gmail.com with ESMTPSA id j143sm1906263itj.16.2019.02.27.14.19.19 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 27 Feb 2019 14:19:19 -0800 (PST) From: Daniel Kurtz Cc: rrangel@chromium.org, Daniel Kurtz , Mathias Nyman , Greg Kroah-Hartman , linux-usb@vger.kernel.org (open list:USB XHCI DRIVER), linux-kernel@vger.kernel.org (open list) Subject: [PATCH] xhci: use iopoll for xhci_handshake Date: Wed, 27 Feb 2019 15:19:17 -0700 Message-Id: <20190227221917.62567-1-djkurtz@chromium.org> X-Mailer: git-send-email 2.21.0.rc2.261.ga7da99ff1b-goog MIME-Version: 1.0 Content-Transfer-Encoding: 8bit To: unlisted-recipients:; (no To-header on input) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In cases such as xhci_abort_cmd_ring(), xhci_handshake() is called with a spin lock held (and local interrupts disabled) with a huge 5 second timeout. This can translates to 5 million calls to udelay(1). By its very nature, udelay() is not meant to be precise, it only guarantees to delay a minimum of 1 microsecond. Therefore the actual delay of xhci_handshake() can be significantly longer. If the average udelay(1) is greater than 2.2 us, the total time in xhci_handshake() - with interrupts disabled can be > 11 seconds triggering the kernel's soft lockup detector. To avoid this, let's replace the open coded io polling loop with one from iopoll.h that uses a loop timed with the more presumably reliable ktime infrastructure. Signed-off-by: Daniel Kurtz --- drivers/usb/host/xhci.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c index 005e65922608e..fde5ff84ba69b 100644 --- a/drivers/usb/host/xhci.c +++ b/drivers/usb/host/xhci.c @@ -16,6 +16,7 @@ #include #include #include +#include #include "xhci.h" #include "xhci-trace.h" @@ -69,18 +70,18 @@ static bool td_on_ring(struct xhci_td *td, struct xhci_ring *ring) int xhci_handshake(void __iomem *ptr, u32 mask, u32 done, int usec) { u32 result; + int ret; - do { - result = readl(ptr); - if (result == ~(u32)0) /* card removed */ - return -ENODEV; - result &= mask; - if (result == done) - return 0; - udelay(1); - usec--; - } while (usec > 0); - return -ETIMEDOUT; + ret = readl_poll_timeout_atomic(ptr, result, + ((result & mask) == done || (result == ~(u32)0)), + 1, usec); + if (ret) + return ret; + + if (result == ~(u32)0) /* card removed */ + return -ENODEV; + + return 0; } /* -- 2.21.0.rc2.261.ga7da99ff1b-goog