rtmutex-debug.c

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/*
 * RT-Mutexes: blocking mutual exclusion locks with PI support
 *
 * started by Ingo Molnar and Thomas Gleixner:
 *
 *  Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <[email protected]>
 *  Copyright (C) 2006 Timesys Corp., Thomas Gleixner <[email protected]>
 *
 * This code is based on the rt.c implementation in the preempt-rt tree.
 * Portions of said code are
 *
 *  Copyright (C) 2004  LynuxWorks, Inc., Igor Manyilov, Bill Huey
 *  Copyright (C) 2006  Esben Nielsen
 *  Copyright (C) 2006  Kihon Technologies Inc.,
 *          Steven Rostedt <[email protected]>
 *
 * See rt.c in preempt-rt for proper credits and further information
 */
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/export.h>
#include <linux/spinlock.h>
#include <linux/kallsyms.h>
#include <linux/syscalls.h>
#include <linux/interrupt.h>
#include <linux/plist.h>
#include <linux/fs.h>
#include <linux/debug_locks.h>

#include "rtmutex_common.h"

static void printk_task(struct task_struct *p)
{
    if (p)
        printk("%16s:%5d [%p, %3d]", p->comm, task_pid_nr(p), p, p->prio);
    else
        printk("<none>");
}

static void printk_lock(struct rt_mutex *lock, int print_owner)
{
    if (lock->name)
        printk(" [%p] {%s}\n",
            lock, lock->name);
    else
        printk(" [%p] {%s:%d}\n",
            lock, lock->file, lock->line);

    if (print_owner && rt_mutex_owner(lock)) {
        printk(".. ->owner: %p\n", lock->owner);
        printk(".. held by:  ");
        printk_task(rt_mutex_owner(lock));
        printk("\n");
    }
}

void rt_mutex_debug_task_free(struct task_struct *task)
{
    DEBUG_LOCKS_WARN_ON(!plist_head_empty(&task->pi_waiters));
    DEBUG_LOCKS_WARN_ON(task->pi_blocked_on);
}

/*
 * We fill out the fields in the waiter to store the information about
 * the deadlock. We print when we return. act_waiter can be NULL in
 * case of a remove waiter operation.
 */
void debug_rt_mutex_deadlock(int detect, struct rt_mutex_waiter *act_waiter,
                 struct rt_mutex *lock)
{
    struct task_struct *task;

    if (!debug_locks || detect || !act_waiter)
        return;

    task = rt_mutex_owner(act_waiter->lock);
    if (task && task != current) {
        act_waiter->deadlock_task_pid = get_pid(task_pid(task));
        act_waiter->deadlock_lock = lock;
    }
}

void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter)
{
    struct task_struct *task;

    if (!waiter->deadlock_lock || !debug_locks)
        return;

    rcu_read_lock();
    task = pid_task(waiter->deadlock_task_pid, PIDTYPE_PID);
    if (!task) {
        rcu_read_unlock();
        return;
    }

    if (!debug_locks_off()) {
        rcu_read_unlock();
        return;
    }

    printk("\n============================================\n");
    printk(  "[ BUG: circular locking deadlock detected! ]\n");
    printk("%s\n", print_tainted());
    printk(  "--------------------------------------------\n");
    printk("%s/%d is deadlocking current task %s/%d\n\n",
           task->comm, task_pid_nr(task),
           current->comm, task_pid_nr(current));

    printk("\n1) %s/%d is trying to acquire this lock:\n",
           current->comm, task_pid_nr(current));
    printk_lock(waiter->lock, 1);

    printk("\n2) %s/%d is blocked on this lock:\n",
        task->comm, task_pid_nr(task));
    printk_lock(waiter->deadlock_lock, 1);

    debug_show_held_locks(current);
    debug_show_held_locks(task);

    printk("\n%s/%d's [blocked] stackdump:\n\n",
        task->comm, task_pid_nr(task));
    show_stack(task, NULL);
    printk("\n%s/%d's [current] stackdump:\n\n",
        current->comm, task_pid_nr(current));
    dump_stack();
    debug_show_all_locks();
    rcu_read_unlock();

    printk("[ turning off deadlock detection."
           "Please report this trace. ]\n\n");
}

void debug_rt_mutex_lock(struct rt_mutex *lock)
{
}

void debug_rt_mutex_unlock(struct rt_mutex *lock)
{
    DEBUG_LOCKS_WARN_ON(rt_mutex_owner(lock) != current);
}

void
debug_rt_mutex_proxy_lock(struct rt_mutex *lock, struct task_struct *powner)
{
}

void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock)
{
    DEBUG_LOCKS_WARN_ON(!rt_mutex_owner(lock));
}

void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
{
    memset(waiter, 0x11, sizeof(*waiter));
    plist_node_init(&waiter->list_entry, MAX_PRIO);
    plist_node_init(&waiter->pi_list_entry, MAX_PRIO);
    waiter->deadlock_task_pid = NULL;
}

void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
{
    put_pid(waiter->deadlock_task_pid);
    DEBUG_LOCKS_WARN_ON(!plist_node_empty(&waiter->list_entry));
    DEBUG_LOCKS_WARN_ON(!plist_node_empty(&waiter->pi_list_entry));
    memset(waiter, 0x22, sizeof(*waiter));
}

void debug_rt_mutex_init(struct rt_mutex *lock, const char *name)
{
    /*
     * Make sure we are not reinitializing a held lock:
     */
    debug_check_no_locks_freed((void *)lock, sizeof(*lock));
    lock->name = name;
}

void
rt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task)
{
}

void rt_mutex_deadlock_account_unlock(struct task_struct *task)
{
}