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eef15e2a54
Commit2aff5e2bc6('tty: Change tty lock order to master->slave') added a warning which is broken and unnecessary now that the tty lock has fixed lock subclasses, added in commit2febdb632b('tty: Preset lock subclass for nested tty locks'). Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
63 lines
1.1 KiB
C
63 lines
1.1 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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tty_lock(tty);
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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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