From 6c80c0b94b94192d9a34b400f8237703c6475f4d Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Thu, 8 Apr 2021 14:51:30 +0200 Subject: tty: move some internal tty lock enums and functions out of tty.h Move the TTY_LOCK_* enums and tty_ldisc lock functions out of the global tty.h into the local header file to clean things up. Cc: Jiri Slaby Link: https://lore.kernel.org/r/20210408125134.3016837-10-gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman --- drivers/tty/tty.h | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) (limited to 'drivers/tty/tty.h') diff --git a/drivers/tty/tty.h b/drivers/tty/tty.h index 55003840cd68..af997a4174c5 100644 --- a/drivers/tty/tty.h +++ b/drivers/tty/tty.h @@ -17,6 +17,32 @@ #define tty_info_ratelimited(tty, f, ...) \ tty_msg(pr_info_ratelimited, tty, f, ##__VA_ARGS__) +/* + * Lock subclasses for tty locks + * + * TTY_LOCK_NORMAL is for normal ttys and master ptys. + * TTY_LOCK_SLAVE is for slave ptys only. + * + * Lock subclasses are necessary for handling nested locking with pty pairs. + * tty locks which use nested locking: + * + * legacy_mutex - Nested tty locks are necessary for releasing pty pairs. + * The stable lock order is master pty first, then slave pty. + * termios_rwsem - The stable lock order is tty_buffer lock->termios_rwsem. + * Subclassing this lock enables the slave pty to hold its + * termios_rwsem when claiming the master tty_buffer lock. + * tty_buffer lock - slave ptys can claim nested buffer lock when handling + * signal chars. The stable lock order is slave pty, then + * master. + */ +enum { + TTY_LOCK_NORMAL = 0, + TTY_LOCK_SLAVE, +}; + +int tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout); +void tty_ldisc_unlock(struct tty_struct *tty); + /* tty_audit.c */ #ifdef CONFIG_AUDIT void tty_audit_add_data(struct tty_struct *tty, const void *data, size_t size); -- cgit v1.2.3-59-g8ed1b