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tty: vt: expect valid vc when in tty ops

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At least since commits feebed6515 ("tty: shutdown method") and
bc1e99d93f ("TTY: vt, add ->install"), tty->driver_data in vc is
expected to be set since tty_operations::install() till ::cleanup().

So the checks of !tty->driver_data (aka !vc) in:
* vc_do_resize() by tty -> ioctl(TIOCSWINSZ) -> vt_resize()
* do_con_write() by tty -> tty_operations::write()/::put_char()
* con_flush_chars() by tty -> ::flush_chars()
are all superfluous. And also, holding a console lock is not needed to
fetch tty->driver_data.

Note there is even a stale comment in con_flush_chars() about a race
between that and con_close(). But con_close() does not set
tty->driver_data to NULL for years already.

Drop all these in a hope I am not terribly mistaken.

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Tested-by: Helge Deller <deller@gmx.de> # parisc STI console
Link: https://lore.kernel.org/r/20240122110401.7289-5-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jiri Slaby (SUSE)
2024-01-22 12:03:18 +01:00
committed by Greg Kroah-Hartman
parent 0e6a92f67c
commit b3dd9bef75
1 changed files with 3 additions and 16 deletions
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19
drivers/tty/vt/vt.c
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@@ -1154,9 +1154,6 @@ static int vc_do_resize(struct tty_struct *tty, struct vc_data *vc,
WARN_CONSOLE_UNLOCKED();
if (!vc)
return -ENXIO;
user = vc->vc_resize_user;
vc->vc_resize_user = 0;
@@ -2852,7 +2849,7 @@ static int do_con_write(struct tty_struct *tty, const u8 *buf, int count)
};
int c, tc, n = 0;
unsigned int currcons;
struct vc_data *vc;
struct vc_data *vc = tty->driver_data;
struct vt_notifier_param param;
bool rescan;
@@ -2860,13 +2857,6 @@ static int do_con_write(struct tty_struct *tty, const u8 *buf, int count)
return count;
console_lock();
vc = tty->driver_data;
if (vc == NULL) {
pr_err("vt: argh, driver_data is NULL !\n");
console_unlock();
return 0;
}
currcons = vc->vc_num;
if (!vc_cons_allocated(currcons)) {
/* could this happen? */
@@ -3312,16 +3302,13 @@ static void con_start(struct tty_struct *tty)
static void con_flush_chars(struct tty_struct *tty)
{
struct vc_data *vc;
struct vc_data *vc = tty->driver_data;
if (in_interrupt()) /* from flush_to_ldisc */
return;
/* if we race with con_close(), vt may be null */
console_lock();
vc = tty->driver_data;
if (vc)
set_cursor(vc);
set_cursor(vc);
console_unlock();
}