From patchwork Sun Apr 23 23:20:43 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: William Breathitt Gray X-Patchwork-Id: 13221494 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 BA2A4C77B76 for ; Sun, 23 Apr 2023 23:21:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230185AbjDWXU6 (ORCPT ); Sun, 23 Apr 2023 19:20:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41438 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230177AbjDWXU5 (ORCPT ); Sun, 23 Apr 2023 19:20:57 -0400 Received: from mail-yb1-xb2f.google.com (mail-yb1-xb2f.google.com [IPv6:2607:f8b0:4864:20::b2f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D65CD10EB for ; Sun, 23 Apr 2023 16:20:55 -0700 (PDT) Received: by mail-yb1-xb2f.google.com with SMTP id 3f1490d57ef6-b98415ba97aso4843664276.0 for ; Sun, 23 Apr 2023 16:20:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1682292055; x=1684884055; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=7P/6zoNdnIVgVCEt5mDoPuKCp+7Gdkmg7/IH03tl/hc=; b=wEk96wY0BNTq4Si5T64xauv4RLRaJkGMx6CMD4mIf694zT68AiY4H/qDevf6Fehfqc JQOOaH/f+33/21XGfmN00faEd8Ew41fsJ357jQWHVdQda35ApZF71jWp1gAqCwMVs1F+ +X8P1x4c3HO3v3jGE7q6d525dYGo+9FxUzp9Hp6ZW7kZ9rjKH0qqSEVhZluxNi+TNvj0 WQjGb5YNeAn9TbOZUszCeGDDpm4ubTNVfUPTudWLST3e6X+6NdNpLDz0DaJAq93ehLBf K6EQIaA+8fFJ++AGF12JVUf0+3blgzzEGroRU9JcExEh5R3A4rOaXoI9kATzMiZkeUGp hy2g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1682292055; x=1684884055; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=7P/6zoNdnIVgVCEt5mDoPuKCp+7Gdkmg7/IH03tl/hc=; b=Ro1qnwKX0hru1SNuhivaBdJM1Nvyf5XZCw4JxNM11A/O5wlfX+46CYYLczK3uFelUF EI/yxqNaX38Vqq+gX6y0qXyDkwuNNXR1ret7ucfVra9gRvtal+OCbUvGsrP38XjJEFwe u/TwrcIUoe5rw+NA0kmy6avzMb0FTrH66EoMtr0yGl62E3/3EbktCqJ+20c1lVE5Klll u2w9EJrqHigSfIFbzUugs/qj9jn4vwQ6m68dGCPVjtrbAhmHy3UoD80l7CmXC3+HOD+e PtaBoewYEo7EMrNNdTJQpDCi+sHTTeLXCY3C5fipavvoS9EWzUnCEAMct7gMUD3OrceR AJlA== X-Gm-Message-State: AAQBX9c2TF4FwjeRemN+6Lr7P4U4l6WCuWPbUNdV+Zdqz/HB8X/t7b1K fpn8tLSs1qqgjmQPlGlvRiVEFJoIKfQxQNQYp5Y= X-Google-Smtp-Source: AKy350ZU8SD5UpSm8QXQFKQlKUpoJGlUSQa8uCIAy8admKw4hyfrd8JMtLXsezp3AJ+E4bCYPoR1OQ== X-Received: by 2002:a25:cac4:0:b0:b8f:2047:181a with SMTP id a187-20020a25cac4000000b00b8f2047181amr8493235ybg.24.1682292055043; Sun, 23 Apr 2023 16:20:55 -0700 (PDT) Received: from fedora.. ([198.136.190.5]) by smtp.gmail.com with ESMTPSA id z205-20020a0dd7d6000000b0054f856bdc4dsm2607352ywd.38.2023.04.23.16.20.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 23 Apr 2023 16:20:54 -0700 (PDT) From: William Breathitt Gray To: Greg Kroah-Hartman Cc: linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Jonathan Cameron , William Breathitt Gray , stable@vger.kernel.org Subject: [PATCH 4.14 v4 1/5] iio: counter: 104-quad-8: Fix race condition between FLAG and CNTR reads Date: Sun, 23 Apr 2023 19:20:43 -0400 Message-Id: <20230423232047.12589-1-william.gray@linaro.org> X-Mailer: git-send-email 2.40.0 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org commit 4aa3b75c74603c3374877d5fd18ad9cc3a9a62ed upstream. The Counter (CNTR) register is 24 bits wide, but we can have an effective 25-bit count value by setting bit 24 to the XOR of the Borrow flag and Carry flag. The flags can be read from the FLAG register, but a race condition exists: the Borrow flag and Carry flag are instantaneous and could change by the time the count value is read from the CNTR register. Since the race condition could result in an incorrect 25-bit count value, remove support for 25-bit count values from this driver. Fixes: 28e5d3bb0325 ("iio: 104-quad-8: Add IIO support for the ACCES 104-QUAD-8") Cc: # 4.14.x Signed-off-by: William Breathitt Gray --- drivers/iio/counter/104-quad-8.c | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-) base-commit: df06e352f27a9f368ec6a3b077881c35d933e32c diff --git a/drivers/iio/counter/104-quad-8.c b/drivers/iio/counter/104-quad-8.c index 181585ae6e..bdb07694e2 100644 --- a/drivers/iio/counter/104-quad-8.c +++ b/drivers/iio/counter/104-quad-8.c @@ -64,9 +64,6 @@ static int quad8_read_raw(struct iio_dev *indio_dev, { struct quad8_iio *const priv = iio_priv(indio_dev); const int base_offset = priv->base + 2 * chan->channel; - unsigned int flags; - unsigned int borrow; - unsigned int carry; int i; switch (mask) { @@ -76,12 +73,7 @@ static int quad8_read_raw(struct iio_dev *indio_dev, return IIO_VAL_INT; } - flags = inb(base_offset + 1); - borrow = flags & BIT(0); - carry = !!(flags & BIT(1)); - - /* Borrow XOR Carry effectively doubles count range */ - *val = (borrow ^ carry) << 24; + *val = 0; /* Reset Byte Pointer; transfer Counter to Output Latch */ outb(0x11, base_offset + 1); From patchwork Sun Apr 23 23:20:44 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: William Breathitt Gray X-Patchwork-Id: 13221495 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 2B92CC77B7C for ; Sun, 23 Apr 2023 23:21:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230235AbjDWXVA (ORCPT ); Sun, 23 Apr 2023 19:21:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41452 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230196AbjDWXU6 (ORCPT ); Sun, 23 Apr 2023 19:20:58 -0400 Received: from mail-yb1-xb33.google.com (mail-yb1-xb33.google.com [IPv6:2607:f8b0:4864:20::b33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ECFE710F9 for ; Sun, 23 Apr 2023 16:20:56 -0700 (PDT) Received: by mail-yb1-xb33.google.com with SMTP id 3f1490d57ef6-b992ed878ebso10019029276.0 for ; Sun, 23 Apr 2023 16:20:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1682292056; x=1684884056; 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=YzAHMc97ie/I1BcVW78M2VJNx9wjhBXHbWDgzi0U6j8=; b=DHVnP7nGrg3vRnIqtPn1Q7mvsvrHjcTern73pfkIbqsV9bRZPyP+MqQ5KrjJfSLW2A ImSGBdVeLWUAHIEaqo1ptnqhYq5k8JfyfS3qnHJvTvV/tJ5j9DWNh2Rnp6PxvxvNgP/a vaxJQXbZbAfwINkpKh1fg+2Jj2yF4CKx949f2oPgiuXGaGqBgCsSPyqL7zyobXg5BKi5 LTbWdtswKpcCYv0oAh41d0mqSd3G1qzTDrCtDXlwl7Tj0a2E7bWhYQA6vFVgqU3ZRS6/ osMpsJUlObexxTVr0xxCfrEZLHcJzr40NjKXCVYbPwuK8mtGtBBy17EYDtkBE+m22ItH t0fA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1682292056; x=1684884056; 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=YzAHMc97ie/I1BcVW78M2VJNx9wjhBXHbWDgzi0U6j8=; b=bjITbNszt4niB8EMAS5qYICud2Y+q8BXVVRCis+ys/6J29YPTuw4yRTz7sZjGtw6ry BP2+l9AFWUfnygLpMA1FpSzCinkVFn847cazELhT7PLqKWVFscu44WVaRUCyKKRBhBXG RkT2x8Xy48j+0uPLospelSEaFE06HnVyphxUtyVH+LD7kx/hiA+KBp0uBuNZuqYCdnNt UoMB+uBm0wauQKPAFU85ASyT+46LBllqlzG+q/5mCSRhiwkuK0aMUymueoCj8h8M3prH octXNWRjy/uUJdnppsonaavOf8U9dk+DIuxb5seQ+DYEQtTVI0Hkt6y0MsWB50vVwF4L UTUA== X-Gm-Message-State: AAQBX9c7BLwDhlQK36Yx+14bDjluxxBljEWim+M7chWmwzfsrZG7QR7o ZRhBJt2+d4OKdT1S0aY3mfSc2DdfK6HetKYW9T4= X-Google-Smtp-Source: AKy350Y4bsziUezOmWgOvpjrp33g5jOYb3Yhg5QNTxK1FyUPU1gTw5mq7+2RSZuXM/1EMS6om+fMYw== X-Received: by 2002:a81:49cb:0:b0:54f:52b7:3eac with SMTP id w194-20020a8149cb000000b0054f52b73eacmr8050321ywa.9.1682292055967; Sun, 23 Apr 2023 16:20:55 -0700 (PDT) Received: from fedora.. ([198.136.190.5]) by smtp.gmail.com with ESMTPSA id z205-20020a0dd7d6000000b0054f856bdc4dsm2607352ywd.38.2023.04.23.16.20.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 23 Apr 2023 16:20:55 -0700 (PDT) From: William Breathitt Gray To: Greg Kroah-Hartman Cc: linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Jonathan Cameron , William Breathitt Gray , stable@vger.kernel.org Subject: [PATCH 4.19 v4 2/5] iio: counter: 104-quad-8: Fix race condition between FLAG and CNTR reads Date: Sun, 23 Apr 2023 19:20:44 -0400 Message-Id: <20230423232047.12589-2-william.gray@linaro.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230423232047.12589-1-william.gray@linaro.org> References: <20230423232047.12589-1-william.gray@linaro.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org commit 4aa3b75c74603c3374877d5fd18ad9cc3a9a62ed upstream. The Counter (CNTR) register is 24 bits wide, but we can have an effective 25-bit count value by setting bit 24 to the XOR of the Borrow flag and Carry flag. The flags can be read from the FLAG register, but a race condition exists: the Borrow flag and Carry flag are instantaneous and could change by the time the count value is read from the CNTR register. Since the race condition could result in an incorrect 25-bit count value, remove support for 25-bit count values from this driver. Fixes: 28e5d3bb0325 ("iio: 104-quad-8: Add IIO support for the ACCES 104-QUAD-8") Cc: # 4.19.x Signed-off-by: William Breathitt Gray --- drivers/iio/counter/104-quad-8.c | 14 +------------- 1 file changed, 1 insertion(+), 13 deletions(-) base-commit: a5b79a58cfc02977cd4d5c1e20454cd98e88f749 diff --git a/drivers/iio/counter/104-quad-8.c b/drivers/iio/counter/104-quad-8.c index 92be8d0f77..92e68cada8 100644 --- a/drivers/iio/counter/104-quad-8.c +++ b/drivers/iio/counter/104-quad-8.c @@ -61,10 +61,6 @@ struct quad8_iio { #define QUAD8_REG_CHAN_OP 0x11 #define QUAD8_REG_INDEX_INPUT_LEVELS 0x16 -/* Borrow Toggle flip-flop */ -#define QUAD8_FLAG_BT BIT(0) -/* Carry Toggle flip-flop */ -#define QUAD8_FLAG_CT BIT(1) /* Error flag */ #define QUAD8_FLAG_E BIT(4) /* Up/Down flag */ @@ -97,9 +93,6 @@ static int quad8_read_raw(struct iio_dev *indio_dev, { struct quad8_iio *const priv = iio_priv(indio_dev); const int base_offset = priv->base + 2 * chan->channel; - unsigned int flags; - unsigned int borrow; - unsigned int carry; int i; switch (mask) { @@ -110,12 +103,7 @@ static int quad8_read_raw(struct iio_dev *indio_dev, return IIO_VAL_INT; } - flags = inb(base_offset + 1); - borrow = flags & QUAD8_FLAG_BT; - carry = !!(flags & QUAD8_FLAG_CT); - - /* Borrow XOR Carry effectively doubles count range */ - *val = (borrow ^ carry) << 24; + *val = 0; /* Reset Byte Pointer; transfer Counter to Output Latch */ outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_BP | QUAD8_RLD_CNTR_OUT, From patchwork Sun Apr 23 23:20:45 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: William Breathitt Gray X-Patchwork-Id: 13221496 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 1F6BEC7EE20 for ; Sun, 23 Apr 2023 23:21:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230186AbjDWXVB (ORCPT ); Sun, 23 Apr 2023 19:21:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41476 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230199AbjDWXU7 (ORCPT ); Sun, 23 Apr 2023 19:20:59 -0400 Received: from mail-yw1-x1130.google.com (mail-yw1-x1130.google.com [IPv6:2607:f8b0:4864:20::1130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C8C5010FB for ; Sun, 23 Apr 2023 16:20:57 -0700 (PDT) Received: by mail-yw1-x1130.google.com with SMTP id 00721157ae682-54fb6ac1e44so44171847b3.1 for ; Sun, 23 Apr 2023 16:20:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1682292057; x=1684884057; 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=uwu1vhLpwiGpAHC/Cs/4RYcqfeSmxKDk74qORfSjerc=; b=KiJIx1lLBudl5/4Qj/SXSbYpb2JKY8zbM6jvYAio1X9nOb1fQ9hXxJQ8Kufczf8IIY JpkjEKSp1YfIO3fP56IzROgCrAXcBt0N1MN7DKTVZqG8UqT50v3N56L1RpXcQ873nCtv TpBAVN92QuLkzRS/iAX8e4BvMnOJqP6bLJfYc5qd+CQhsHJTx/XiWm1UpDi4wiIwooEi QcG4g3zGOBGa+qdPX4WXD5klcZ/qEKAsBPIKxhRmZpD4L1Mnl3xV1QxIBlhbvK0MGpbM PPTLz+PoOp+r3XhvRKScO2EgT4ptDqLIP22Dy+38rTLL7MpsvhWo//Vk4U6LElLiaxw0 wqTg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1682292057; x=1684884057; 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=uwu1vhLpwiGpAHC/Cs/4RYcqfeSmxKDk74qORfSjerc=; b=hNoJ3a3wq3jzC3HHvWa9085qm/IwPtwabzRYXFM/Od6a4jisEw7LwSaLR+mdfbt3FK iKzSQhKktHFJ7R6LCLFCI1PM9GWwF4rtRFdM4na/8uQ8clNplHyPLvvDE1RGU+iWHSCw LmK+tp/4CfhW3ZrpyrtEok3SKeHmUMfgUcxjnAiyUatpsYw/PXpnd/E3lEMk+Nco+XTv bKiVWFg8aCjKIH8k2Q2PgO/77IYr2XLbm4SsQ75Fl2jPaeT4FG6OCmfnDoJNpPXe/i7X pYS/3LJ4LOriQzdk551fVedTj03K8D/sGyQKyqtchNDs3fmTa7Kj2ipjKGi1DQtuyCW9 pFuA== X-Gm-Message-State: AAQBX9dTWgqJN4FAmfwddRIRI1Uv6wF5dHH76ZDO+1doM4LqYtomY5mH 4q5J3t7oGqgF9gM+31IYgAdK2LdvrnSDihwWKoA= X-Google-Smtp-Source: AKy350aKIQWgrvAgAAvztgDvqheIbGCFbUU49e68tH9Z7HssooWmErHS4yQsKScaMjot4tO5ooOuHA== X-Received: by 2002:a0d:ed07:0:b0:54e:b6b2:1bba with SMTP id w7-20020a0ded07000000b0054eb6b21bbamr6777137ywe.0.1682292056933; Sun, 23 Apr 2023 16:20:56 -0700 (PDT) Received: from fedora.. ([198.136.190.5]) by smtp.gmail.com with ESMTPSA id z205-20020a0dd7d6000000b0054f856bdc4dsm2607352ywd.38.2023.04.23.16.20.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 23 Apr 2023 16:20:56 -0700 (PDT) From: William Breathitt Gray To: Greg Kroah-Hartman Cc: linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Jonathan Cameron , William Breathitt Gray , stable@vger.kernel.org Subject: [PATCH 5.4 v4 3/5] counter: 104-quad-8: Fix race condition between FLAG and CNTR reads Date: Sun, 23 Apr 2023 19:20:45 -0400 Message-Id: <20230423232047.12589-3-william.gray@linaro.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230423232047.12589-1-william.gray@linaro.org> References: <20230423232047.12589-1-william.gray@linaro.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org commit 4aa3b75c74603c3374877d5fd18ad9cc3a9a62ed upstream. The Counter (CNTR) register is 24 bits wide, but we can have an effective 25-bit count value by setting bit 24 to the XOR of the Borrow flag and Carry flag. The flags can be read from the FLAG register, but a race condition exists: the Borrow flag and Carry flag are instantaneous and could change by the time the count value is read from the CNTR register. Since the race condition could result in an incorrect 25-bit count value, remove support for 25-bit count values from this driver. Fixes: 28e5d3bb0325 ("iio: 104-quad-8: Add IIO support for the ACCES 104-QUAD-8") Cc: # 5.4.x Signed-off-by: William Breathitt Gray --- drivers/counter/104-quad-8.c | 20 +++----------------- 1 file changed, 3 insertions(+), 17 deletions(-) base-commit: 58f42ed1cd31238745bddd943c4f5849dc83a2ac diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c index f261a57af1..48de69f58e 100644 --- a/drivers/counter/104-quad-8.c +++ b/drivers/counter/104-quad-8.c @@ -57,10 +57,6 @@ struct quad8_iio { #define QUAD8_REG_CHAN_OP 0x11 #define QUAD8_REG_INDEX_INPUT_LEVELS 0x16 -/* Borrow Toggle flip-flop */ -#define QUAD8_FLAG_BT BIT(0) -/* Carry Toggle flip-flop */ -#define QUAD8_FLAG_CT BIT(1) /* Error flag */ #define QUAD8_FLAG_E BIT(4) /* Up/Down flag */ @@ -639,19 +635,9 @@ static int quad8_count_read(struct counter_device *counter, { struct quad8_iio *const priv = counter->priv; const int base_offset = priv->base + 2 * count->id; - unsigned int flags; - unsigned int borrow; - unsigned int carry; - unsigned long position; + unsigned long position = 0; int i; - flags = inb(base_offset + 1); - borrow = flags & QUAD8_FLAG_BT; - carry = !!(flags & QUAD8_FLAG_CT); - - /* Borrow XOR Carry effectively doubles count range */ - position = (unsigned long)(borrow ^ carry) << 24; - mutex_lock(&priv->lock); /* Reset Byte Pointer; transfer Counter to Output Latch */ @@ -1204,8 +1190,8 @@ static ssize_t quad8_count_ceiling_read(struct counter_device *counter, mutex_unlock(&priv->lock); - /* By default 0x1FFFFFF (25 bits unsigned) is maximum count */ - return sprintf(buf, "33554431\n"); + /* By default 0xFFFFFF (24 bits unsigned) is maximum count */ + return sprintf(buf, "16777215\n"); } static ssize_t quad8_count_ceiling_write(struct counter_device *counter, From patchwork Sun Apr 23 23:20:46 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: William Breathitt Gray X-Patchwork-Id: 13221497 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 CAB87C7EE21 for ; Sun, 23 Apr 2023 23:21:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230251AbjDWXVC (ORCPT ); Sun, 23 Apr 2023 19:21:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41494 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230219AbjDWXVA (ORCPT ); Sun, 23 Apr 2023 19:21:00 -0400 Received: from mail-yw1-x112f.google.com (mail-yw1-x112f.google.com [IPv6:2607:f8b0:4864:20::112f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D99FF10F3 for ; Sun, 23 Apr 2023 16:20:58 -0700 (PDT) Received: by mail-yw1-x112f.google.com with SMTP id 00721157ae682-54f9d6eccf3so44136997b3.2 for ; Sun, 23 Apr 2023 16:20:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1682292058; x=1684884058; 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=cthSXcBD9iVVm3blHORVesLHvMRZmvd8/QCQdXoEC9w=; b=GWjo56mOVxMl3/ic3j4OMgChqlqhOWUjboVme/sgNAmexMKgwhq5r3VnqgqBwOG4q2 kxfQtGAfprBou0GxqWhlhL3m6SFg0pdlqdp+yQ7dj7JLoW6ewPrpYepLO2g9/MsDmOJz cVBTVaH8tPsn1xSPdZxgSgARwrwUd7GmJ83/gXesp1mMUv4EEjm+F+cH41TAkrOBmdY+ m/WXjupw6/uCBbQ/EMlT7V33mUMOpAybNRdZeOZUySmMgsi1Sh//waXvkReGkiJMB2HW dnPBZ4Uebcm8Xn89cIrrb18cBkhKcLrVwqLOAtCWZCs6YZf3seZeC3Cr7V9ncqcwVt7T PjFQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1682292058; x=1684884058; 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=cthSXcBD9iVVm3blHORVesLHvMRZmvd8/QCQdXoEC9w=; b=eUU3Yo+C3AWA9vPS2NPo3wV8Mo1IBnFWMobwrXOY8ntgiK6CnhLgLTVBTYyVUe+Lsf 8g/3TbuhC0jAYj8Hs4l9/unqvpmvY5sZfT1xqn+5YzfmV15xHkIbEcPNw/zSB8NzuTfe RPDhPu5MnA/wtUkzg57FOvJWoX3faamoG1auktMFWTNzm6NzW5Ed2uo/hDcgiGDfaBRk oJiBmvCi033kgXkd/eyTabcJvWf1F4OfeRlHd4EUb4YCmO/BnqOvt94DKaS50hZE6nvt 1xrZEiEyZxjVsLckG/WDJv6ccz0CidHKNyV/THUanGe3D8PugB7pCzVo56YKUcgxk/B8 tJSw== X-Gm-Message-State: AAQBX9dzcWaF16JwjakE7k66tQUvMGcI94fgcla2HbD72XAOouTMnTy4 ls/R3MSiSvTIRD8NrLZcwSEuglg384832gN0M2Q= X-Google-Smtp-Source: AKy350Z967+MY7g96A5l7axv+F6eC9z/8DRdK5wXWyezSDx8VydBB1G/9jvkKKVaRPE6QkO4MRmmRg== X-Received: by 2002:a81:838b:0:b0:54f:df51:7422 with SMTP id t133-20020a81838b000000b0054fdf517422mr6176587ywf.34.1682292058026; Sun, 23 Apr 2023 16:20:58 -0700 (PDT) Received: from fedora.. ([198.136.190.5]) by smtp.gmail.com with ESMTPSA id z205-20020a0dd7d6000000b0054f856bdc4dsm2607352ywd.38.2023.04.23.16.20.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 23 Apr 2023 16:20:57 -0700 (PDT) From: William Breathitt Gray To: Greg Kroah-Hartman Cc: linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Jonathan Cameron , William Breathitt Gray , stable@vger.kernel.org Subject: [PATCH 5.10 v4 4/5] counter: 104-quad-8: Fix race condition between FLAG and CNTR reads Date: Sun, 23 Apr 2023 19:20:46 -0400 Message-Id: <20230423232047.12589-4-william.gray@linaro.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230423232047.12589-1-william.gray@linaro.org> References: <20230423232047.12589-1-william.gray@linaro.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org commit 4aa3b75c74603c3374877d5fd18ad9cc3a9a62ed upstream. The Counter (CNTR) register is 24 bits wide, but we can have an effective 25-bit count value by setting bit 24 to the XOR of the Borrow flag and Carry flag. The flags can be read from the FLAG register, but a race condition exists: the Borrow flag and Carry flag are instantaneous and could change by the time the count value is read from the CNTR register. Since the race condition could result in an incorrect 25-bit count value, remove support for 25-bit count values from this driver. Fixes: 28e5d3bb0325 ("iio: 104-quad-8: Add IIO support for the ACCES 104-QUAD-8") Cc: # 5.10.x Signed-off-by: William Breathitt Gray --- drivers/counter/104-quad-8.c | 18 +++--------------- 1 file changed, 3 insertions(+), 15 deletions(-) base-commit: 791a854ae5a5f5988f1291ae91168a149bd5ba57 diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c index 21bb2bb767..1b4fdee9d9 100644 --- a/drivers/counter/104-quad-8.c +++ b/drivers/counter/104-quad-8.c @@ -62,10 +62,6 @@ struct quad8_iio { #define QUAD8_REG_CHAN_OP 0x11 #define QUAD8_REG_INDEX_INPUT_LEVELS 0x16 #define QUAD8_DIFF_ENCODER_CABLE_STATUS 0x17 -/* Borrow Toggle flip-flop */ -#define QUAD8_FLAG_BT BIT(0) -/* Carry Toggle flip-flop */ -#define QUAD8_FLAG_CT BIT(1) /* Error flag */ #define QUAD8_FLAG_E BIT(4) /* Up/Down flag */ @@ -643,17 +639,9 @@ static int quad8_count_read(struct counter_device *counter, { struct quad8_iio *const priv = counter->priv; const int base_offset = priv->base + 2 * count->id; - unsigned int flags; - unsigned int borrow; - unsigned int carry; int i; - flags = inb(base_offset + 1); - borrow = flags & QUAD8_FLAG_BT; - carry = !!(flags & QUAD8_FLAG_CT); - - /* Borrow XOR Carry effectively doubles count range */ - *val = (unsigned long)(borrow ^ carry) << 24; + *val = 0; mutex_lock(&priv->lock); @@ -1198,8 +1186,8 @@ static ssize_t quad8_count_ceiling_read(struct counter_device *counter, mutex_unlock(&priv->lock); - /* By default 0x1FFFFFF (25 bits unsigned) is maximum count */ - return sprintf(buf, "33554431\n"); + /* By default 0xFFFFFF (24 bits unsigned) is maximum count */ + return sprintf(buf, "16777215\n"); } static ssize_t quad8_count_ceiling_write(struct counter_device *counter, From patchwork Sun Apr 23 23:20:47 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: William Breathitt Gray X-Patchwork-Id: 13221498 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 B1B11C77B60 for ; Sun, 23 Apr 2023 23:21:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230257AbjDWXVD (ORCPT ); Sun, 23 Apr 2023 19:21:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41532 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230196AbjDWXVB (ORCPT ); Sun, 23 Apr 2023 19:21:01 -0400 Received: from mail-yb1-xb2e.google.com (mail-yb1-xb2e.google.com [IPv6:2607:f8b0:4864:20::b2e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 000B8170F for ; Sun, 23 Apr 2023 16:20:59 -0700 (PDT) Received: by mail-yb1-xb2e.google.com with SMTP id 3f1490d57ef6-b9965b0b5e9so826463276.1 for ; Sun, 23 Apr 2023 16:20:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1682292059; x=1684884059; 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=HUMSPEP1V3AMPMfycyCyPWow7154NmJhwDd6EB+MKNQ=; b=Z8y6B1JfGkmvceYC7a0xDwfOvKwhNmXRbWSUWNRkcYpwR+Al/8842fXxkZGelkzbR6 TmmlljPUcEmVv3F0VG2IbWqNxAxeqIxxmBHhqUg7eQ3SpK8ebYd02BjK5pnqReE0QkDD Av6cA9KZeSq8B3wK0H31MTcQ9z5Y7g9LLaXdGn1I00QpA065Qqncc1VzGwQojpQZsIWa F6yOqXFa2ovHaStEVnKjzOO0kbKOkwjLjm+5Xw5Oj4PinPM/fZkZiGaXwyxM+euJ6nte LgLo2J+b5QtI/JdX08L3IRscNQT16jjaOL1hylIvWDzStyZmwYr7Wel14gyHEJ5e0mQS V9Nw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1682292059; x=1684884059; 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=HUMSPEP1V3AMPMfycyCyPWow7154NmJhwDd6EB+MKNQ=; b=O22NayS23DxE0MZmF20uoReZ2sL+qS8VfK0oYxhsXOea0yQoMgQKliE/Kwr8AiyP2B 6wSQONrLO1eq7OJFFL3hJTb9tyErKVNFAHQX98jLW3iVwgCA2pB5Yvd18iu+4IqDhTLk RSs/jRZBrM1vb5KQ7QD/I47vBe3GtPMm+GtXVV2lhNPBLdDMkzZe5CmQuoiKDNobsDvo hjwOJCqeMSbHKxNK6mcBxMmMA7kSvdPOlKUZXEH7SmTBra0Tz8fccFCGUB7loyROp/ht imjFrQM7e1iEdoy12JwJvJ9ErCZjBuQA9eYO4uGo4Zi3WK/4umO/82d1iUE5Oq8d+PoK mNgQ== X-Gm-Message-State: AAQBX9fHVaViMQ5IHsyUrKVql60CWIahV+eA+y8M695zu91nJ9wjqEhc dhLfgNZaZ7fCjy9lkN3BkVgVYA== X-Google-Smtp-Source: AKy350YxOvXAAQvroRp0u+02NfJgfQuykjpvRsULkTAPwPKJpwCpSBfOaDyXyIh5iiCaxapepy/aEQ== X-Received: by 2002:a81:6606:0:b0:541:7e07:ed65 with SMTP id a6-20020a816606000000b005417e07ed65mr6790710ywc.5.1682292059112; Sun, 23 Apr 2023 16:20:59 -0700 (PDT) Received: from fedora.. ([198.136.190.5]) by smtp.gmail.com with ESMTPSA id z205-20020a0dd7d6000000b0054f856bdc4dsm2607352ywd.38.2023.04.23.16.20.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 23 Apr 2023 16:20:58 -0700 (PDT) From: William Breathitt Gray To: Greg Kroah-Hartman Cc: linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Jonathan Cameron , William Breathitt Gray , stable@vger.kernel.org Subject: [PATCH 5.15 v4 5/5] counter: 104-quad-8: Fix race condition between FLAG and CNTR reads Date: Sun, 23 Apr 2023 19:20:47 -0400 Message-Id: <20230423232047.12589-5-william.gray@linaro.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230423232047.12589-1-william.gray@linaro.org> References: <20230423232047.12589-1-william.gray@linaro.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org commit 4aa3b75c74603c3374877d5fd18ad9cc3a9a62ed upstream. The Counter (CNTR) register is 24 bits wide, but we can have an effective 25-bit count value by setting bit 24 to the XOR of the Borrow flag and Carry flag. The flags can be read from the FLAG register, but a race condition exists: the Borrow flag and Carry flag are instantaneous and could change by the time the count value is read from the CNTR register. Since the race condition could result in an incorrect 25-bit count value, remove support for 25-bit count values from this driver; hard-coded maximum count values are replaced by a LS7267_CNTR_MAX define for consistency and clarity. Fixes: 28e5d3bb0325 ("iio: 104-quad-8: Add IIO support for the ACCES 104-QUAD-8") Cc: # 5.15.x Signed-off-by: William Breathitt Gray --- drivers/counter/104-quad-8.c | 29 ++++++++--------------------- 1 file changed, 8 insertions(+), 21 deletions(-) base-commit: 3299fb36854fdc288bddc2c4d265f8a2e5105944 diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c index e00cf156c6..ab2c49579b 100644 --- a/drivers/counter/104-quad-8.c +++ b/drivers/counter/104-quad-8.c @@ -61,10 +61,6 @@ struct quad8 { #define QUAD8_REG_CHAN_OP 0x11 #define QUAD8_REG_INDEX_INPUT_LEVELS 0x16 #define QUAD8_DIFF_ENCODER_CABLE_STATUS 0x17 -/* Borrow Toggle flip-flop */ -#define QUAD8_FLAG_BT BIT(0) -/* Carry Toggle flip-flop */ -#define QUAD8_FLAG_CT BIT(1) /* Error flag */ #define QUAD8_FLAG_E BIT(4) /* Up/Down flag */ @@ -97,6 +93,9 @@ struct quad8 { #define QUAD8_CMR_QUADRATURE_X2 0x10 #define QUAD8_CMR_QUADRATURE_X4 0x18 +/* Each Counter is 24 bits wide */ +#define LS7267_CNTR_MAX GENMASK(23, 0) + static int quad8_signal_read(struct counter_device *counter, struct counter_signal *signal, enum counter_signal_level *level) @@ -121,17 +120,9 @@ static int quad8_count_read(struct counter_device *counter, { struct quad8 *const priv = counter->priv; const int base_offset = priv->base + 2 * count->id; - unsigned int flags; - unsigned int borrow; - unsigned int carry; int i; - flags = inb(base_offset + 1); - borrow = flags & QUAD8_FLAG_BT; - carry = !!(flags & QUAD8_FLAG_CT); - - /* Borrow XOR Carry effectively doubles count range */ - *val = (unsigned long)(borrow ^ carry) << 24; + *val = 0; mutex_lock(&priv->lock); @@ -154,8 +145,7 @@ static int quad8_count_write(struct counter_device *counter, const int base_offset = priv->base + 2 * count->id; int i; - /* Only 24-bit values are supported */ - if (val > 0xFFFFFF) + if (val > LS7267_CNTR_MAX) return -ERANGE; mutex_lock(&priv->lock); @@ -627,8 +617,7 @@ static int quad8_count_preset_write(struct counter_device *counter, { struct quad8 *const priv = counter->priv; - /* Only 24-bit values are supported */ - if (preset > 0xFFFFFF) + if (preset > LS7267_CNTR_MAX) return -ERANGE; mutex_lock(&priv->lock); @@ -654,8 +643,7 @@ static int quad8_count_ceiling_read(struct counter_device *counter, *ceiling = priv->preset[count->id]; break; default: - /* By default 0x1FFFFFF (25 bits unsigned) is maximum count */ - *ceiling = 0x1FFFFFF; + *ceiling = LS7267_CNTR_MAX; break; } @@ -669,8 +657,7 @@ static int quad8_count_ceiling_write(struct counter_device *counter, { struct quad8 *const priv = counter->priv; - /* Only 24-bit values are supported */ - if (ceiling > 0xFFFFFF) + if (ceiling > LS7267_CNTR_MAX) return -ERANGE; mutex_lock(&priv->lock);