2febdb632b
Eliminate the requirement of specifying the tty lock nesting at lock time; instead, set the lock subclass for slave ptys at pty install (normal ttys and master ptys use subclass 0). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
67 lines
1.3 KiB
C
67 lines
1.3 KiB
C
#include <linux/tty.h>
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#include <linux/module.h>
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#include <linux/kallsyms.h>
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#include <linux/semaphore.h>
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#include <linux/sched.h>
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/*
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* Nested tty locks are necessary for releasing pty pairs.
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* The stable lock order is master pty first, then slave pty.
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*/
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/* Legacy tty mutex glue */
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enum {
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TTY_MUTEX_NORMAL,
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TTY_MUTEX_SLAVE,
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};
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/*
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* Getting the big tty mutex.
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*/
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void __lockfunc tty_lock(struct tty_struct *tty)
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{
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if (tty->magic != TTY_MAGIC) {
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pr_err("L Bad %p\n", tty);
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WARN_ON(1);
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return;
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}
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tty_kref_get(tty);
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mutex_lock(&tty->legacy_mutex);
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}
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EXPORT_SYMBOL(tty_lock);
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void __lockfunc tty_unlock(struct tty_struct *tty)
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{
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if (tty->magic != TTY_MAGIC) {
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pr_err("U Bad %p\n", tty);
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WARN_ON(1);
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return;
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}
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mutex_unlock(&tty->legacy_mutex);
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tty_kref_put(tty);
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}
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EXPORT_SYMBOL(tty_unlock);
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void __lockfunc tty_lock_slave(struct tty_struct *tty)
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{
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if (tty && tty != tty->link) {
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WARN_ON(!mutex_is_locked(&tty->link->legacy_mutex) ||
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!tty->driver->type == TTY_DRIVER_TYPE_PTY ||
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!tty->driver->type == PTY_TYPE_SLAVE);
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tty_lock(tty);
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}
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}
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void __lockfunc tty_unlock_slave(struct tty_struct *tty)
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{
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if (tty && tty != tty->link)
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tty_unlock(tty);
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}
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void tty_set_lock_subclass(struct tty_struct *tty)
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{
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lockdep_set_subclass(&tty->legacy_mutex, TTY_MUTEX_SLAVE);
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}
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