From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ej1-f51.google.com (mail-ej1-f51.google.com [209.85.218.51]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 61B56372B41 for ; Sun, 2 Aug 2026 11:39:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.218.51 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785670772; cv=none; b=MCf1hNM48JnljyFG7GwjPFqaLayf7GrvjB1GbGySKIBUM5yT2e9IVIzwlhbzDVOwV8cyv1MkTKMm3QauTUWvvpA+Hy28UZGrhHEEZrABfHVXPpa8mZOfPrRBGHneUw8z6jxZPeZS75hn3fk7kHXYJDwbmlKg7t+zl/tRC8C3kYU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785670772; c=relaxed/simple; bh=T4R1HNsXMnCpyaFzZ4pXogBKQizbRCcSIqBkfGB4Lac=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=ExwcsoIiPLOPpVXdA1zJc/Ha98uTZQwjDBzHhld0VPGMY/H91X4w7dUfBO4CSsu1J7DbE3F+KD3tQIAKAWgdhZpQ/Dk5Oafo+h/E1NjykVA/Mp8PfF4pNjGwlkxuYSZ7PnfVdSnHQmjsiwhQ85OCVJevTfvoXVqfCJnBlna3sYE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=ZlUcjfC1; arc=none smtp.client-ip=209.85.218.51 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ZlUcjfC1" Received: by mail-ej1-f51.google.com with SMTP id a640c23a62f3a-c15ba3a2b4bso298277366b.1 for ; Sun, 02 Aug 2026 04:39:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1785670758; x=1786275558; darn=lists.linux.dev; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to:content-type; bh=+7ecKSNcW7KFUMBHUns97kjKTa+UXCrK+tcT7T4tgGY=; b=ZlUcjfC115RIS7fKbaVZGSBzDZ0otMqTj5cXi3JqCrq/YocoUlSfKKYneOSKkPRCel KkhvBKwNTFYcsJDAlPSPboYtMoPCU4rsABY4i6rdhgdsVOXkS3NevSJ343VQOK3tY2SD vBTfaeKg8lALdVPmggi7MAGXr+eu+iRY8G2+uoWJYN82LZGaoXIPDZuAeuNKuj/NANJH A8plT0O84SrDtCmBK43Lz0xAyMOXBdsYCVsQPvuHddh5aGNfbBmSeEIrBlwP3wxTR/E2 S+V7ptDllExwVWTLhbGRg4a0MKOh/0b44yDZm2cMlY5DV7AZyZnEZ/jG4qsjLTVOqnyh TI/A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1785670758; x=1786275558; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=+7ecKSNcW7KFUMBHUns97kjKTa+UXCrK+tcT7T4tgGY=; b=oHdKESzZ8kiF2nac5MA89rg9zjJAgkziKAaypYJW+0rEKh82XVOu+6ztTOa0IsFJms VjHd6tKxpi7612iyJ56UbpXqL5lu6MokqrJ4NYSqnTXxn11oP1FyYoUCAWewUq/ABdp4 3XJL48NzlcEJqAsF66TcxOHVIBZDGi/a1CFwYx3L7aaW+Cw5T6b2G4RgA60MuyvItXEI aMlLNiIavv3Ze+x1RrwxGiGdYK3/aGkAcNodiBRh/8S4pjnX33yD5ZksCs4lMRZ7I1Mn ptCAsB42kCq/Z8vxItoEt00Eo8hdflJMMbSVtChdng81XjeS5ffTCHCragirSDC0dRus 1/MQ== X-Forwarded-Encrypted: i=1; AHgh+RqJTKP8YbizBYgHxnDdgcBFCK9cSQSnwdKrFfqK37kiqXBjwoElLP0W47Kh8DeFml7UJFePSCH1PA/COcdy@lists.linux.dev X-Gm-Message-State: AOJu0Yw5gRiPSQrdyJHHmZ0RNpnQngReEod8uTQdKg/Sk75aTKdlJZQn 43Tb/1cZoDmHi2ClvEzGKBVd91bZervYX/0DM5L2OoQ779cMTA7dfqMR X-Gm-Gg: AR+sD13ylDxB41a7QXWWzgjIIt12TM+MmayW2ZMHEXKa7SSBZf848zVf8/6MCvWRcDv vDOigLb41WJrqZoUp/yEueLK0nFaqtymGBYAGq+3pfM9vH3mVAZ/ijyAhHoyOhXuCWDQOBneg5f PAt4pYQPS/qS95G4Kvxccu2J17uR6Cmxr9Pd2E9ETXGzpIpDhSWEfillriTDssY1UdqqFUWoAur UfG6RA3B5YXZ0yJGqrsWi4+RFGBamVasEwJQhm3VtgvMV6WqAFNa+26ZaiuDoW9B6mjw068oYPG XP61egbZvJG8x6jUPOgqSn6jE7NfcsS+coOPq0pGdsn0rxeWqYu2IjH6M2nzfvSnNHvo2xdzLxa EiDfbUHNNya9PVaSMCT7Q6qZpb68CNdAUsA+5Dp0GsiOHV4MCupjk6rIB9Y2qv88wSLPKaJ5BCl 7skIz8zh8YgniV0hsTZkfkbi7oDfR9ph2LmHbX3syBqtIQdOQhyfDh3BFOmgeU+hKTuXEz/CjuX 0Rwt+vYbQ== X-Received: by 2002:a17:906:fe42:b0:c16:3074:657f with SMTP id a640c23a62f3a-c1fe7ecb6d3mr535636766b.9.1785670758004; Sun, 02 Aug 2026 04:39:18 -0700 (PDT) Received: from fedora ([154.182.104.97]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c1fd4532e1esm407679966b.50.2026.08.02.04.39.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 02 Aug 2026 04:39:16 -0700 (PDT) From: Abdelnasser Hussein To: nuno.sa@analog.com, Michael.Hennerich@analog.com, jic23@kernel.org, gregkh@linuxfoundation.org Cc: dlechner@baylibre.com, andy@kernel.org, linux@analog.com, linux-iio@vger.kernel.org, linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org, Abdelnasser Hussein Subject: [PATCH] staging: iio: ad7816: avoid DMA from stack in spi_read Date: Sun, 2 Aug 2026 14:38:40 +0300 Message-ID: <20260802113840.17730-1-abdelnasserhussein11@gmail.com> X-Mailer: git-send-email 2.54.0 Precedence: bulk X-Mailing-List: linux-staging@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The SPI core may use DMA for transfers. Using a stack-allocated buffer for DMA is unsafe and can trigger faults when VMAP_STACK is enabled, since the stack is not guaranteed to be DMA-accessible. Move the transfer buffer from the stack into the ad7816_chip_info structure so it has a stable lifetime suitable for DMA transfers. Mark the buffer with ____cacheline_aligned to ensure proper alignment for DMA operations. Signed-off-by: Abdelnasser Hussein --- drivers/staging/iio/adc/ad7816.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/drivers/staging/iio/adc/ad7816.c b/drivers/staging/iio/adc/ad7816.c index 0e32a2295990..fcaadebff0f4 100644 --- a/drivers/staging/iio/adc/ad7816.c +++ b/drivers/staging/iio/adc/ad7816.c @@ -50,6 +50,7 @@ struct ad7816_chip_info { u8 oti_data[AD7816_CS_MAX + 1]; u8 channel_id; /* 0 always be temperature */ u8 mode; + __be16 rx_buf ____cacheline_aligned; }; enum ad7816_type { @@ -65,7 +66,6 @@ static int ad7816_spi_read(struct ad7816_chip_info *chip, u16 *data) { struct spi_device *spi_dev = chip->spi_dev; int ret; - __be16 buf; gpiod_set_value(chip->rdwr_pin, 1); gpiod_set_value(chip->rdwr_pin, 0); @@ -91,14 +91,12 @@ static int ad7816_spi_read(struct ad7816_chip_info *chip, u16 *data) gpiod_set_value(chip->rdwr_pin, 0); gpiod_set_value(chip->rdwr_pin, 1); - ret = spi_read(spi_dev, &buf, sizeof(*data)); + ret = spi_read(spi_dev, &chip->rx_buf, sizeof(chip->rx_buf)); if (ret < 0) { dev_err(&spi_dev->dev, "SPI data read error\n"); return ret; } - - *data = be16_to_cpu(buf); - + *data = be16_to_cpu(chip->rx_buf); return ret; } -- 2.54.0