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tty: Remove chars_in_buffer() line discipline method

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The chars_in_buffer() line discipline method serves no functional
purpose, other than as a (dubious) debugging aid for mostly bit-rotting
drivers. Despite being documented as an optional method, every caller
is unconditionally executed (although conditionally compiled).
Furthermore, direct tty->ldisc access without an ldisc ref is unsafe.
Lastly, N_TTY's chars_in_buffer() has warned of removal since 3.12.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Peter Hurley
2016-01-10 22:40:54 -08:00
committed by Greg Kroah-Hartman
parent 582e20a03b
commit fdfb719e93
8 changed files with 13 additions and 68 deletions
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16
drivers/tty/n_gsm.c
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@@ -2303,21 +2303,6 @@ static void gsmld_receive_buf(struct tty_struct *tty, const unsigned char *cp,
/* If clogged call tty_throttle(tty); */
}
/**
* gsmld_chars_in_buffer - report available bytes
* @tty: tty device
*
* Report the number of characters buffered to be delivered to user
* at this instant in time.
*
* Locking: gsm lock
*/
static ssize_t gsmld_chars_in_buffer(struct tty_struct *tty)
{
return 0;
}
/**
* gsmld_flush_buffer - clean input queue
* @tty: terminal device
@@ -2830,7 +2815,6 @@ static struct tty_ldisc_ops tty_ldisc_packet = {
.open = gsmld_open,
.close = gsmld_close,
.flush_buffer = gsmld_flush_buffer,
.chars_in_buffer = gsmld_chars_in_buffer,
.read = gsmld_read,
.write = gsmld_write,
.ioctl = gsmld_ioctl,