Re: [PATCH v1] treewide, serdev: change receive_buf() return type to size_t

Johan Hovold
2023-12-15T13:51:21Z

On Thu, Dec 14, 2023 at 06:01:46PM +0100, Francesco Dolcini wrote:
> From: Francesco Dolcini <francesco.dolcini@toradex.com>
>
> 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.
>
> Suggested-by: Jiri Slaby <jirislaby@kernel.org>
> Link: https://lore.kernel.org/all/087be419-ec6b-47ad-851a-5e1e3ea5cfcc@kernel.org/
> Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
> ---
> hello,
> patch is based on current linux next.
>
> It has an obvious problem, it touches files from multiple subsystem in a single
> patch that is complicated to review and eventually merge, just splitting this
> would however not work, it will break bisectability and the build.
>
> I am looking for advise on the best way to move forward.
>
> I see the following options:
> - keep it as it is
> - break it down with a patch with each subsystem, and squash before applying
> from a single (tty?) subsystem
> - go for a multi stage approach, defining a new callback, move to it and in
> the end remove the original one, likewise it was done for i2c lately
>
> ---
> drivers/bluetooth/btmtkuart.c | 4 ++--
> drivers/bluetooth/btnxpuart.c | 4 ++--

> diff --git a/drivers/bluetooth/btmtkuart.c b/drivers/bluetooth/btmtkuart.c
> index 3c84fcbda01a..e6bc4a73c9fc 100644
> --- a/drivers/bluetooth/btmtkuart.c
> +++ b/drivers/bluetooth/btmtkuart.c
> @@ -383,8 +383,8 @@ static void btmtkuart_recv(struct hci_dev *hdev, const u8 *data, size_t count)
> }
> }
>
> -static ssize_t btmtkuart_receive_buf(struct serdev_device *serdev,
> - const u8 *data, size_t count)
> +static size_t btmtkuart_receive_buf(struct serdev_device *serdev,
> + const u8 *data, size_t count)
> {
> struct btmtkuart_dev *bdev = serdev_device_get_drvdata(serdev);
>
> diff --git a/drivers/bluetooth/btnxpuart.c b/drivers/bluetooth/btnxpuart.c
> index 1d592ac413d1..056bef5b2919 100644
> --- a/drivers/bluetooth/btnxpuart.c
> +++ b/drivers/bluetooth/btnxpuart.c
> @@ -1264,8 +1264,8 @@ static const struct h4_recv_pkt nxp_recv_pkts[] = {
> { NXP_RECV_FW_REQ_V3, .recv = nxp_recv_fw_req_v3 },
> };
>
> -static ssize_t btnxpuart_receive_buf(struct serdev_device *serdev,
> - const u8 *data, size_t count)
> +static size_t btnxpuart_receive_buf(struct serdev_device *serdev,
> + const u8 *data, size_t count)
> {
> struct btnxpuart_dev *nxpdev = serdev_device_get_drvdata(serdev);

A quick check of just the first two functions here shows that they can
return negative values.

> diff --git a/drivers/tty/serdev/serdev-ttyport.c b/drivers/tty/serdev/serdev-ttyport.c
> index e94e090cf0a1..3d7ae7fa5018 100644
> --- a/drivers/tty/serdev/serdev-ttyport.c
> +++ b/drivers/tty/serdev/serdev-ttyport.c
> @@ -27,19 +27,17 @@ static size_t ttyport_receive_buf(struct tty_port *port, const u8 *cp,
> {
> struct serdev_controller *ctrl = port->client_data;
> struct serport *serport = serdev_controller_get_drvdata(ctrl);
> - int ret;
> + size_t ret;
>
> if (!test_bit(SERPORT_ACTIVE, &serport->flags))
> return 0;
>
> ret = serdev_controller_receive_buf(ctrl, cp, count);
>
> - dev_WARN_ONCE(&ctrl->dev, ret < 0 || ret > count,
> - "receive_buf returns %d (count = %zu)\n",
> + dev_WARN_ONCE(&ctrl->dev, ret > count,
> + "receive_buf returns %zu (count = %zu)\n",
> ret, count);
> - if (ret < 0)
> - return 0;
> - else if (ret > count)
> + if (ret > count)
> return count;
>
> return ret;

So please do not apply this patch until the various implementations have
been fixed.

Johan