From nobody Wed Feb 11 20:06:00 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7E927CA0EC3 for ; Mon, 11 Sep 2023 21:39:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349794AbjIKVex (ORCPT ); Mon, 11 Sep 2023 17:34:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53772 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244217AbjIKTjr (ORCPT ); Mon, 11 Sep 2023 15:39:47 -0400 Received: from mail-pj1-x102a.google.com (mail-pj1-x102a.google.com [IPv6:2607:f8b0:4864:20::102a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7FCE51B8 for ; Mon, 11 Sep 2023 12:39:42 -0700 (PDT) Received: by mail-pj1-x102a.google.com with SMTP id 98e67ed59e1d1-26d50a832a9so3339579a91.3 for ; Mon, 11 Sep 2023 12:39:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1694461182; x=1695065982; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=gdCNmE4TQzaUVGYBpjExxVlAWo5NcVTWN45t1mLK2Kw=; b=ogpttftmeuGXskkeyI7t4md+uLYnvUs0J/Pn3eJnYCUi/XytZcLFKUOVj3ijBzWBnO lJlDS1XHOVyvuJSBwO2U8D49Cx1zJ3IJSWBDxs2I/hGrWFvW1G+Q7AhJEaqoDt5mG7Fs QoHCsnruJJxVE7zckenLWst++1VoWlgJV8HGs= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1694461182; x=1695065982; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=gdCNmE4TQzaUVGYBpjExxVlAWo5NcVTWN45t1mLK2Kw=; b=mdiuWQd2Gx2fGkCLJWgejcILGgqE/f+T9lU5iFm/VPhfCq2hYoaf8oubywFkzyrF16 2dP784ZoQRAbYPbkfBh2eBkMvQ+WzNh5Ra/csoQUIEqlHDSbKKSpxh7lFHF/eOyIKE6v T+6o7g7pMUW4sJVLlW2KCrUtT0ugd4GPhv34F4V38b+EMhVlMm1HH+zqI1Z0Pt502lZp o1VPDrXW+bHPYVH74PpX2D35E2AB0HAANIIEBt0NCp5eeemTtp8Dos3/VKuMLsZeu1I4 lfC0AnKvDHWzKIZzA3gaGo0BsGoVziy0eRcxsYWEXNhhQTOdldK+IQ8NJ42Td93TU3S1 ZTPg== X-Gm-Message-State: AOJu0YyWWjhI3s2oqjoSb4cy4Ty9RkQCFo6MbIKAIirWHMx5eYFysd8x V3aeY9dAXI5PHN/Gw5yxh/VU6g== X-Google-Smtp-Source: AGHT+IGGvlqWnCd6FgKie+c4RBzySbl2Wtfy49TuNcsKhZkbb20DCZlYeRe7ju+YlMJNU0euA/ADjA== X-Received: by 2002:a17:90a:c246:b0:263:ebab:a152 with SMTP id d6-20020a17090ac24600b00263ebaba152mr8240717pjx.19.1694461181946; Mon, 11 Sep 2023 12:39:41 -0700 (PDT) Received: from smtp.gmail.com ([2620:15c:11a:201:d487:5e33:6656:3711]) by smtp.gmail.com with ESMTPSA id fu8-20020a17090ad18800b00262e485156esm7736543pjb.57.2023.09.11.12.39.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 11 Sep 2023 12:39:41 -0700 (PDT) From: Stephen Boyd To: Mika Westerberg , Hans de Goede , Mark Gross Cc: linux-kernel@vger.kernel.org, patches@lists.linux.dev, platform-driver-x86@vger.kernel.org, Andy Shevchenko , Kuppuswamy Sathyanarayanan , Prashant Malani Subject: [PATCH v3 1/4] platform/x86: intel_scu_ipc: Check status after timeout in busy_loop() Date: Mon, 11 Sep 2023 12:39:33 -0700 Message-ID: <20230911193937.302552-2-swboyd@chromium.org> X-Mailer: git-send-email 2.42.0.283.g2d96d420d3-goog In-Reply-To: <20230911193937.302552-1-swboyd@chromium.org> References: <20230911193937.302552-1-swboyd@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" It's possible for the polling loop in busy_loop() to get scheduled away for a long time. status =3D ipc_read_status(scu); // status =3D IPC_STATUS_BUSY if (!(status & IPC_STATUS_BUSY)) If this happens, then the status bit could change while the task is scheduled away and this function would never read the status again after timing out. Instead, the function will return -ETIMEDOUT when it's possible that scheduling didn't work out and the status bit was cleared. Bit polling code should always check the bit being polled one more time after the timeout in case this happens. Fix this by reading the status once more after the while loop breaks. The read_poll_timeout() macro implements all of this, and it is shorter, so use that macro here to consolidate code and fix this. There were some concerns with using read_poll_timeout() because it uses timekeeping, and timekeeping isn't running early on or during the late stages of system suspend or early stages of system resume, but an audit of the code concluded that this code isn't called during those times so it is safe to use the macro. Cc: Prashant Malani Cc: Andy Shevchenko Fixes: e7b7ab3847c9 ("platform/x86: intel_scu_ipc: Sleeping is fine when po= lling") Signed-off-by: Stephen Boyd Reviewed-by: Andy Shevchenko Reviewed-by: Kuppuswamy Sathyanarayanan Reviewed-by: Mika Westerberg --- drivers/platform/x86/intel_scu_ipc.c | 19 ++++++++----------- 1 file changed, 8 insertions(+), 11 deletions(-) diff --git a/drivers/platform/x86/intel_scu_ipc.c b/drivers/platform/x86/in= tel_scu_ipc.c index 6851d10d6582..5a37becc65aa 100644 --- a/drivers/platform/x86/intel_scu_ipc.c +++ b/drivers/platform/x86/intel_scu_ipc.c @@ -19,6 +19,7 @@ #include #include #include +#include #include #include =20 @@ -231,19 +232,15 @@ static inline u32 ipc_data_readl(struct intel_scu_ipc= _dev *scu, u32 offset) /* Wait till scu status is busy */ static inline int busy_loop(struct intel_scu_ipc_dev *scu) { - unsigned long end =3D jiffies + IPC_TIMEOUT; + u8 status; + int err; =20 - do { - u32 status; + err =3D read_poll_timeout(ipc_read_status, status, !(status & IPC_STATUS_= BUSY), + 100, jiffies_to_usecs(IPC_TIMEOUT), false, scu); + if (err) + return err; =20 - status =3D ipc_read_status(scu); - if (!(status & IPC_STATUS_BUSY)) - return (status & IPC_STATUS_ERR) ? -EIO : 0; - - usleep_range(50, 100); - } while (time_before(jiffies, end)); - - return -ETIMEDOUT; + return (status & IPC_STATUS_ERR) ? -EIO : 0; } =20 /* Wait till ipc ioc interrupt is received or timeout in 10 HZ */ --=20 https://chromeos.dev