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![Pavel Emelyanov](/assets/img/avatar_default.png)
The proper behavior to store task's pid and get this task later is to get the struct pid pointer and get the task with the pid_task() call. Make it for rt_mutex_waiter->deadlock_task_pid field. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
239 lines
5.7 KiB
C
239 lines
5.7 KiB
C
/*
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* RT-Mutexes: blocking mutual exclusion locks with PI support
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*
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* started by Ingo Molnar and Thomas Gleixner:
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*
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* Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
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* Copyright (C) 2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com>
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*
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* This code is based on the rt.c implementation in the preempt-rt tree.
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* Portions of said code are
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*
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* Copyright (C) 2004 LynuxWorks, Inc., Igor Manyilov, Bill Huey
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* Copyright (C) 2006 Esben Nielsen
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* Copyright (C) 2006 Kihon Technologies Inc.,
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* Steven Rostedt <rostedt@goodmis.org>
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*
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* See rt.c in preempt-rt for proper credits and further information
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*/
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#include <linux/sched.h>
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#include <linux/delay.h>
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#include <linux/module.h>
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#include <linux/spinlock.h>
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#include <linux/kallsyms.h>
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#include <linux/syscalls.h>
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#include <linux/interrupt.h>
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#include <linux/plist.h>
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#include <linux/fs.h>
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#include <linux/debug_locks.h>
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#include "rtmutex_common.h"
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# define TRACE_WARN_ON(x) WARN_ON(x)
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# define TRACE_BUG_ON(x) BUG_ON(x)
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# define TRACE_OFF() \
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do { \
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if (rt_trace_on) { \
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rt_trace_on = 0; \
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console_verbose(); \
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if (spin_is_locked(¤t->pi_lock)) \
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spin_unlock(¤t->pi_lock); \
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} \
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} while (0)
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# define TRACE_OFF_NOLOCK() \
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do { \
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if (rt_trace_on) { \
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rt_trace_on = 0; \
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console_verbose(); \
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} \
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} while (0)
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# define TRACE_BUG_LOCKED() \
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do { \
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TRACE_OFF(); \
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BUG(); \
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} while (0)
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# define TRACE_WARN_ON_LOCKED(c) \
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do { \
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if (unlikely(c)) { \
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TRACE_OFF(); \
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WARN_ON(1); \
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} \
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} while (0)
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# define TRACE_BUG_ON_LOCKED(c) \
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do { \
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if (unlikely(c)) \
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TRACE_BUG_LOCKED(); \
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} while (0)
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#ifdef CONFIG_SMP
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# define SMP_TRACE_BUG_ON_LOCKED(c) TRACE_BUG_ON_LOCKED(c)
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#else
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# define SMP_TRACE_BUG_ON_LOCKED(c) do { } while (0)
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#endif
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/*
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* deadlock detection flag. We turn it off when we detect
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* the first problem because we dont want to recurse back
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* into the tracing code when doing error printk or
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* executing a BUG():
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*/
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static int rt_trace_on = 1;
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static void printk_task(struct task_struct *p)
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{
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if (p)
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printk("%16s:%5d [%p, %3d]", p->comm, task_pid_nr(p), p, p->prio);
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else
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printk("<none>");
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}
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static void printk_lock(struct rt_mutex *lock, int print_owner)
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{
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if (lock->name)
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printk(" [%p] {%s}\n",
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lock, lock->name);
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else
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printk(" [%p] {%s:%d}\n",
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lock, lock->file, lock->line);
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if (print_owner && rt_mutex_owner(lock)) {
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printk(".. ->owner: %p\n", lock->owner);
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printk(".. held by: ");
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printk_task(rt_mutex_owner(lock));
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printk("\n");
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}
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}
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void rt_mutex_debug_task_free(struct task_struct *task)
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{
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WARN_ON(!plist_head_empty(&task->pi_waiters));
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WARN_ON(task->pi_blocked_on);
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}
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/*
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* We fill out the fields in the waiter to store the information about
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* the deadlock. We print when we return. act_waiter can be NULL in
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* case of a remove waiter operation.
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*/
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void debug_rt_mutex_deadlock(int detect, struct rt_mutex_waiter *act_waiter,
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struct rt_mutex *lock)
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{
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struct task_struct *task;
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if (!rt_trace_on || detect || !act_waiter)
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return;
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task = rt_mutex_owner(act_waiter->lock);
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if (task && task != current) {
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act_waiter->deadlock_task_pid = get_pid(task_pid(task));
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act_waiter->deadlock_lock = lock;
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}
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}
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void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter)
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{
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struct task_struct *task;
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if (!waiter->deadlock_lock || !rt_trace_on)
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return;
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rcu_read_lock();
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task = pid_task(waiter->deadlock_task_pid, PIDTYPE_PID);
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if (!task) {
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rcu_read_unlock();
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return;
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}
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TRACE_OFF_NOLOCK();
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printk("\n============================================\n");
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printk( "[ BUG: circular locking deadlock detected! ]\n");
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printk( "--------------------------------------------\n");
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printk("%s/%d is deadlocking current task %s/%d\n\n",
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task->comm, task_pid_nr(task),
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current->comm, task_pid_nr(current));
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printk("\n1) %s/%d is trying to acquire this lock:\n",
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current->comm, task_pid_nr(current));
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printk_lock(waiter->lock, 1);
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printk("\n2) %s/%d is blocked on this lock:\n",
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task->comm, task_pid_nr(task));
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printk_lock(waiter->deadlock_lock, 1);
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debug_show_held_locks(current);
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debug_show_held_locks(task);
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printk("\n%s/%d's [blocked] stackdump:\n\n",
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task->comm, task_pid_nr(task));
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show_stack(task, NULL);
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printk("\n%s/%d's [current] stackdump:\n\n",
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current->comm, task_pid_nr(current));
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dump_stack();
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debug_show_all_locks();
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rcu_read_unlock();
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printk("[ turning off deadlock detection."
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"Please report this trace. ]\n\n");
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local_irq_disable();
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}
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void debug_rt_mutex_lock(struct rt_mutex *lock)
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{
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}
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void debug_rt_mutex_unlock(struct rt_mutex *lock)
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{
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TRACE_WARN_ON_LOCKED(rt_mutex_owner(lock) != current);
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}
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void
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debug_rt_mutex_proxy_lock(struct rt_mutex *lock, struct task_struct *powner)
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{
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}
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void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock)
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{
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TRACE_WARN_ON_LOCKED(!rt_mutex_owner(lock));
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}
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void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
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{
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memset(waiter, 0x11, sizeof(*waiter));
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plist_node_init(&waiter->list_entry, MAX_PRIO);
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plist_node_init(&waiter->pi_list_entry, MAX_PRIO);
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waiter->deadlock_task_pid = NULL;
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}
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void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
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{
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put_pid(waiter->deadlock_task_pid);
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TRACE_WARN_ON(!plist_node_empty(&waiter->list_entry));
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TRACE_WARN_ON(!plist_node_empty(&waiter->pi_list_entry));
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TRACE_WARN_ON(waiter->task);
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memset(waiter, 0x22, sizeof(*waiter));
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}
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void debug_rt_mutex_init(struct rt_mutex *lock, const char *name)
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{
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/*
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* Make sure we are not reinitializing a held lock:
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*/
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debug_check_no_locks_freed((void *)lock, sizeof(*lock));
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lock->name = name;
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}
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void
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rt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task)
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{
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}
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void rt_mutex_deadlock_account_unlock(struct task_struct *task)
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{
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}
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