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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-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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/ad7= 816.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; }; =20 enum ad7816_type { @@ -65,7 +66,6 @@ static int ad7816_spi_read(struct ad7816_chip_info *chip,= u16 *data) { struct spi_device *spi_dev =3D chip->spi_dev; int ret; - __be16 buf; =20 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 *chi= p, u16 *data) =20 gpiod_set_value(chip->rdwr_pin, 0); gpiod_set_value(chip->rdwr_pin, 1); - ret =3D spi_read(spi_dev, &buf, sizeof(*data)); + ret =3D 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 =3D be16_to_cpu(buf); - + *data =3D be16_to_cpu(chip->rx_buf); return ret; } =20 --=20 2.54.0