48 lines
1000 B
C
48 lines
1000 B
C
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/*
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* drivers/char/tty_lock.c
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*/
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#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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* The 'big tty mutex'
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*
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* This mutex is taken and released by tty_lock() and tty_unlock(),
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* replacing the older big kernel lock.
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* It can no longer be taken recursively, and does not get
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* released implicitly while sleeping.
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*
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* Don't use in new code.
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*/
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static DEFINE_MUTEX(big_tty_mutex);
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struct task_struct *__big_tty_mutex_owner;
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EXPORT_SYMBOL_GPL(__big_tty_mutex_owner);
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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(void)
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{
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struct task_struct *task = current;
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WARN_ON(__big_tty_mutex_owner == task);
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mutex_lock(&big_tty_mutex);
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__big_tty_mutex_owner = task;
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}
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EXPORT_SYMBOL(tty_lock);
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void __lockfunc tty_unlock(void)
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{
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struct task_struct *task = current;
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WARN_ON(__big_tty_mutex_owner != task);
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__big_tty_mutex_owner = NULL;
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mutex_unlock(&big_tty_mutex);
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}
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EXPORT_SYMBOL(tty_unlock);
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