/* * 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 (raw_spin_is_locked(¤t->pi_lock)) \ raw_spin_unlock(¤t->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) { }