On Wed, Oct 19, 2022 at 01:55:03PM +0300, Ilpo Järvinen wrote:
> The struct tty_buffer has flags which is only used for storing TTYB_NORMAL.
> There is also a few quite confusing operations for checking the presense
> of TTYB_NORMAL. Simplify things by converting flags to bool.
>
> Despite the name remaining the same, the meaning of "flags" is altered
> slightly by this change. Previously it referred to flags of the buffer
> (only TTYB_NORMAL being used as a flag). After this change, flags tell
> whether the buffer contains/should be allocated with flags array along
> with character data array. It is much more suitable name that
> TTYB_NORMAL was for this purpose, thus the name remains.
>
> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
> ---
>
> v2:
> - Make it more obvious why flags is not renamed (both in kerneldoc
> comment and commit message).
>
> drivers/tty/tty_buffer.c | 28 ++++++++++++++--------------
> include/linux/tty_buffer.h | 5 +----
> include/linux/tty_flip.h | 4 ++--
> 3 files changed, 17 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
> index 5e287dedce01..b408d830fcbc 100644
> --- a/drivers/tty/tty_buffer.c
> +++ b/drivers/tty/tty_buffer.c
> @@ -107,7 +107,7 @@ static void tty_buffer_reset(struct tty_buffer *p, size_t size)
> p->commit = 0;
> p->lookahead = 0;
> p->read = 0;
> - p->flags = 0;
> + p->flags = true;
> }
>
> /**
> @@ -249,7 +249,7 @@ void tty_buffer_flush(struct tty_struct *tty, struct tty_ldisc *ld)
> * __tty_buffer_request_room - grow tty buffer if needed
> * @port: tty port
> * @size: size desired
> - * @flags: buffer flags if new buffer allocated (default = 0)
> + * @flags: buffer has to store flags along character data
> *
> * Make at least @size bytes of linear space available for the tty buffer.
> *
> @@ -260,19 +260,19 @@ void tty_buffer_flush(struct tty_struct *tty, struct tty_ldisc *ld)
> * Returns: the size we managed to find.
> */
> static int __tty_buffer_request_room(struct tty_port *port, size_t size,
> - int flags)
> + bool flags)
> {
> struct tty_bufhead *buf = &port->buf;
> struct tty_buffer *b, *n;
> int left, change;
>
> b = buf->tail;
> - if (b->flags & TTYB_NORMAL)
> + if (!b->flags)
> left = 2 * b->size - b->used;
> else
> left = b->size - b->used;
>
> - change = (b->flags & TTYB_NORMAL) && (~flags & TTYB_NORMAL);
> + change = !b->flags && flags;
> if (change || left < size) {
> /* This is the slow path - looking for new buffers to use */
> n = tty_buffer_alloc(port, size);
> @@ -300,7 +300,7 @@ static int __tty_buffer_request_room(struct tty_port *port, size_t size,
>
> int tty_buffer_request_room(struct tty_port *port, size_t size)
> {
> - return __tty_buffer_request_room(port, size, 0);
> + return __tty_buffer_request_room(port, size, true);
Did this logic just get inverted?
Maybe it's the jet-lag, but this feels like it's not correct anymore.
Maybe a commet up above where you calculate "left" would make more sense
as to what is going on?
thanks,
greg k-h
