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Mon, 02 Mar 2026 05:06:52 -0800 (PST) From: Archit Anant To: jic23@kernel.org, lars@metafoo.de, Michael.Hennerich@analog.com Cc: dlechner@baylibre.com, nuno.sa@analog.com, andy@kernel.org, linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Archit Anant Subject: [PATCH v3 1/4] iio: adc: ad799x: make rx_buf static and DMA-safe Date: Mon, 2 Mar 2026 18:36:29 +0530 Message-Id: <20260302130632.29144-2-architanant5@gmail.com> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20260302130632.29144-1-architanant5@gmail.com> References: <20260302130632.29144-1-architanant5@gmail.com> 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" Currently, rx_buf is dynamically allocated using kmalloc() every time ad799x_update_scan_mode() is called. This can lead to memory leaks if the scan mask is updated multiple times. Drop the dynamic allocation and replace it with a static, buffer at the end of the state structure using IIO_DECLARE_DMA_BUFFER_WITH_TS(). This eliminates the allocation overhead, prevents leaks, and removes the need for manual kfree() on driver removal. Suggested-by: David Lechner Signed-off-by: Archit Anant --- drivers/iio/adc/ad799x.c | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-) diff --git a/drivers/iio/adc/ad799x.c b/drivers/iio/adc/ad799x.c index 108bb22162ef..7775be874081 100644 --- a/drivers/iio/adc/ad799x.c +++ b/drivers/iio/adc/ad799x.c @@ -39,6 +39,7 @@ #include =20 #define AD799X_CHANNEL_SHIFT 4 +#define AD799X_MAX_CHANNELS 8 =20 /* * AD7991, AD7995 and AD7999 defines @@ -133,8 +134,8 @@ struct ad799x_state { unsigned int id; u16 config; =20 - u8 *rx_buf; unsigned int transfer_size; + IIO_DECLARE_DMA_BUFFER_WITH_TS(__be16, rx_buf, AD799X_MAX_CHANNELS); }; =20 static int ad799x_write_config(struct ad799x_state *st, u16 val) @@ -217,11 +218,11 @@ static irqreturn_t ad799x_trigger_handler(int irq, vo= id *p) } =20 b_sent =3D i2c_smbus_read_i2c_block_data(st->client, - cmd, st->transfer_size, st->rx_buf); + cmd, st->transfer_size, (u8 *)st->rx_buf); if (b_sent < 0) goto out; =20 - iio_push_to_buffers_with_timestamp(indio_dev, st->rx_buf, + iio_push_to_buffers_with_timestamp(indio_dev, &st->rx_buf, iio_get_time_ns(indio_dev)); out: iio_trigger_notify_done(indio_dev->trig); @@ -234,11 +235,6 @@ static int ad799x_update_scan_mode(struct iio_dev *ind= io_dev, { struct ad799x_state *st =3D iio_priv(indio_dev); =20 - kfree(st->rx_buf); - st->rx_buf =3D kmalloc(indio_dev->scan_bytes, GFP_KERNEL); - if (!st->rx_buf) - return -ENOMEM; - st->transfer_size =3D bitmap_weight(scan_mask, iio_get_masklength(indio_dev)) * 2; =20 @@ -895,7 +891,6 @@ static void ad799x_remove(struct i2c_client *client) if (st->vref) regulator_disable(st->vref); regulator_disable(st->reg); - kfree(st->rx_buf); } =20 static int ad799x_suspend(struct device *dev) --=20 2.39.5