Re: [PATCH v2] treewide, serdev: change receive_buf() return type to size_t

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]


On 1/22/24 12:05 PM, Francesco Dolcini wrote:
From: Francesco Dolcini <francesco.dolcini@xxxxxxxxxxx>

receive_buf() is called from ttyport_receive_buf() that expects values
">= 0" from serdev_controller_receive_buf(), change its return type from
ssize_t to size_t.

The need for this clean-up was noticed while fixing a warning, see
commit 94d053942544 ("Bluetooth: btnxpuart: fix recv_buf() return value").
Changing the callback prototype to return an unsigned seems the best way
to document the API and ensure that is properly used.

GNSS drivers implementation of serdev receive_buf() callback return
directly the return value of gnss_insert_raw(). gnss_insert_raw()
returns a signed int, however this is not an issue since the value
returned is always positive, because of the kfifo_in() implementation.


gnss_insert_raw() could be changed to return also an unsigned, however
this is not implemented here as request by the GNSS maintainer Johan

I was going to suggest this, and suggest changing the "ret" in
gnss_insert_raw() to return size_t.  But to really do that right
it would include some other changes as well.  Leaving it as an
int as Johan suggests preserves correct behavior.

One minor point below, plus a couple comments affirming that
an int return value is OK because it's always non-negative.

Reviewed-by: Alex Elder <elder@xxxxxxxxxx>

Suggested-by: Jiri Slaby <jirislaby@xxxxxxxxxx>
Signed-off-by: Francesco Dolcini <francesco.dolcini@xxxxxxxxxxx>
Acked-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> #for-iio
  - rebased on 6.8-rc1
  - add acked-by Jonathan
  - do not change gnss_insert_raw()
  - do not change the code style of the gnss code
  - commit message improvements, explain the reasons for doing only minimal
    changes on the GNSS part
  drivers/bluetooth/btmtkuart.c              |  4 ++--
  drivers/bluetooth/btnxpuart.c              |  4 ++--
  drivers/bluetooth/hci_serdev.c             |  4 ++--
  drivers/gnss/serial.c                      |  2 +-
  drivers/gnss/sirf.c                        |  2 +-
  drivers/greybus/gb-beagleplay.c            |  6 +++---
  drivers/iio/chemical/pms7003.c             |  4 ++--
  drivers/iio/chemical/scd30_serial.c        |  4 ++--
  drivers/iio/chemical/sps30_serial.c        |  4 ++--
  drivers/iio/imu/bno055/bno055_ser_core.c   |  4 ++--
  drivers/mfd/rave-sp.c                      |  4 ++--
  drivers/net/ethernet/qualcomm/qca_uart.c   |  2 +-
  drivers/nfc/pn533/uart.c                   |  4 ++--
  drivers/nfc/s3fwrn5/uart.c                 |  4 ++--
  drivers/platform/chrome/cros_ec_uart.c     |  4 ++--
  drivers/platform/surface/aggregator/core.c |  4 ++--
  drivers/tty/serdev/serdev-ttyport.c        | 10 ++++------
  include/linux/serdev.h                     |  8 ++++----
  sound/drivers/serial-generic.c             |  4 ++--
  19 files changed, 40 insertions(+), 42 deletions(-)

. . .

diff --git a/drivers/mfd/rave-sp.c b/drivers/mfd/rave-sp.c
index 6ff84b2600c5..62a6613fb070 100644
--- a/drivers/mfd/rave-sp.c
+++ b/drivers/mfd/rave-sp.c
@@ -471,8 +471,8 @@ static void rave_sp_receive_frame(struct rave_sp *sp,
  		rave_sp_receive_reply(sp, data, length);
-static ssize_t rave_sp_receive_buf(struct serdev_device *serdev,
-				   const u8 *buf, size_t size)
+static size_t rave_sp_receive_buf(struct serdev_device *serdev,
+				  const u8 *buf, size_t size)
  	struct device *dev = &serdev->dev;
  	struct rave_sp *sp = dev_get_drvdata(dev);

One return path in this function returns (src - buf), which is
*almost* guaranteed to be positive.  The one case it wouldn't
be is if the assignment of end wraps around, and that's not

I think it's fine, but... That seems theoretically possible.

diff --git a/drivers/net/ethernet/qualcomm/qca_uart.c b/drivers/net/ethernet/qualcomm/qca_uart.c
index 223321897b96..20f50bde82ac 100644

. . .

diff --git a/drivers/platform/surface/aggregator/core.c b/drivers/platform/surface/aggregator/core.c
index 9591a28bc38a..ba550eaa06fc 100644
--- a/drivers/platform/surface/aggregator/core.c
+++ b/drivers/platform/surface/aggregator/core.c
@@ -227,8 +227,8 @@ EXPORT_SYMBOL_GPL(ssam_client_bind);
/* -- Glue layer (serdev_device -> ssam_controller). ------------------------ */ -static ssize_t ssam_receive_buf(struct serdev_device *dev, const u8 *buf,
-				size_t n)
+static size_t ssam_receive_buf(struct serdev_device *dev, const u8 *buf,
+			       size_t n)
  	struct ssam_controller *ctrl;
  	int ret;

Here you the return value will be positive despite ret being
a signed int.  So like the GNSS case, this is OK.

diff --git a/drivers/tty/serdev/serdev-ttyport.c b/drivers/tty/serdev/serdev-ttyport.c
index e94e090cf0a1..3d7ae7fa5018 100644

. . .

diff --git a/sound/drivers/serial-generic.c b/sound/drivers/serial-generic.c
index d6e5aafd697c..36409a56c675 100644
--- a/sound/drivers/serial-generic.c
+++ b/sound/drivers/serial-generic.c
@@ -100,8 +100,8 @@ static void snd_serial_generic_write_wakeup(struct serdev_device *serdev)
-static ssize_t snd_serial_generic_receive_buf(struct serdev_device *serdev,
-					      const u8 *buf, size_t count)
+static size_t snd_serial_generic_receive_buf(struct serdev_device *serdev,
+					     const u8 *buf, size_t count)
  	int ret;
  	struct snd_serial_generic *drvdata = serdev_device_get_drvdata(serdev);

Same thing here.

[Index of Archives]     [Linux Kernel Development]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux