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SubjectRe: [Patch v8 1/6] tty: add new helper function tty_get_tiocm


On 2023-11-20 08:21, Jiri Slaby wrote:
> On 09. 11. 23, 9:50, Florian Eckert wrote:
>> There is no in-kernel function to get the status register of a tty
>> device
>> like the TIOCMGET ioctl returns to userspace. Create a new function,
>> tty_get_tiocm(), to obtain the status register that other portions of
>> the
>> kernel can call if they need this information, and move the existing
>> internal tty_tiocmget() function to use this interface.
>>
>> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>> Signed-off-by: Florian Eckert <fe@dev.tdt.de>
>> ---
>> drivers/tty/tty_io.c | 28 ++++++++++++++++++++++------
>> include/linux/tty.h | 1 +
>> 2 files changed, 23 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
>> index 06414e43e0b5..e2e93404133e 100644
>> --- a/drivers/tty/tty_io.c
>> +++ b/drivers/tty/tty_io.c
>> @@ -2498,6 +2498,24 @@ static int send_break(struct tty_struct *tty,
>> unsigned int duration)
>> return retval;
>> }
>> +/**
>> + * tty_get_tiocm - get tiocm status register
>> + * @tty: tty device
>> + *
>> + * Obtain the modem status bits from the tty driver if the feature
>> + * is supported.
>> + */
>> +int tty_get_tiocm(struct tty_struct *tty)
>> +{
>> + int retval = -ENOTTY;
>> +
>> + if (tty->ops->tiocmget)
>> + retval = tty->ops->tiocmget(tty);
>> +
>> + return retval;
>
> Why not simply:

I just did it this way because it is also done this way in other
functions
in this file.

> {
> if (tty->ops->tiocmget)
> return tty->ops->tiocmget(tty);
>
> return -ENOTTY;
> }

Of course, we could also do it this way. If this is the C style for the
kernel,
then I will change it. Please give me a short feedback whether I should
change it
and send a v9, or whether it is just a comment from you.

Best regards

Florian

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