root/kernel/rtmutex-debug.c

DEFINITIONS

1. printk_task
2. printk_lock
3. rt_mutex_debug_task_free
4. debug_rt_mutex_deadlock
5. debug_rt_mutex_print_deadlock
6. debug_rt_mutex_lock
7. debug_rt_mutex_unlock
8. debug_rt_mutex_proxy_lock
9. debug_rt_mutex_proxy_unlock
10. debug_rt_mutex_init_waiter
11. debug_rt_mutex_free_waiter
12. debug_rt_mutex_init
13. rt_mutex_deadlock_account_lock
14. rt_mutex_deadlock_account_unlock

/*
 * 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 <mingo@redhat.com>
 *  Copyright (C) 2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com>
 *
 * 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 <rostedt@goodmis.org>
 *
 * See rt.c in preempt-rt for proper credits and further information
 */
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/module.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"

# define TRACE_WARN_ON(x)                       WARN_ON(x)
# define TRACE_BUG_ON(x)                        BUG_ON(x)

# define TRACE_OFF()                                            \
do {                                                            \
        if (rt_trace_on) {                                      \
                rt_trace_on = 0;                                \
                console_verbose();                              \
                if (spin_is_locked(&current->pi_lock))          \
                        spin_unlock(&current->pi_lock);         \
        }                                                       \
} while (0)

# define TRACE_OFF_NOLOCK()                                     \
do {                                                            \
        if (rt_trace_on) {                                      \
                rt_trace_on = 0;                                \
                console_verbose();                              \
        }                                                       \
} while (0)

# define TRACE_BUG_LOCKED()                     \
do {                                            \
        TRACE_OFF();                            \
        BUG();                                  \
} while (0)

# define TRACE_WARN_ON_LOCKED(c)                \
do {                                            \
        if (unlikely(c)) {                      \
                TRACE_OFF();                    \
                WARN_ON(1);                     \
        }                                       \
} while (0)

# define TRACE_BUG_ON_LOCKED(c)                 \
do {                                            \
        if (unlikely(c))                        \
                TRACE_BUG_LOCKED();             \
} while (0)

#ifdef CONFIG_SMP
# define SMP_TRACE_BUG_ON_LOCKED(c)     TRACE_BUG_ON_LOCKED(c)
#else
# define SMP_TRACE_BUG_ON_LOCKED(c)     do { } while (0)
#endif

/*
 * deadlock detection flag. We turn it off when we detect
 * the first problem because we dont want to recurse back
 * into the tracing code when doing error printk or
 * executing a BUG():
 */
static int rt_trace_on = 1;

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)
{
        WARN_ON(!plist_head_empty(&task->pi_waiters));
        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 (!rt_trace_on || 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 || !rt_trace_on)
                return;

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

        TRACE_OFF_NOLOCK();

        printk("\n============================================\n");
        printk(  "[ BUG: circular locking deadlock detected! ]\n");
        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");
        local_irq_disable();
}

void debug_rt_mutex_lock(struct rt_mutex *lock)
{
}

void debug_rt_mutex_unlock(struct rt_mutex *lock)
{
        TRACE_WARN_ON_LOCKED(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)
{
        TRACE_WARN_ON_LOCKED(!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);
        TRACE_WARN_ON(!plist_node_empty(&waiter->list_entry));
        TRACE_WARN_ON(!plist_node_empty(&waiter->pi_list_entry));
        TRACE_WARN_ON(waiter->task);
        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)
{
}