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

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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@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Florian Eckert <fe@xxxxxxxxxx>
---
  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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