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![Ingo Molnar](/assets/img/avatar_default.png)
Runtime debugging functionality for rt-mutexes. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
513 lines
13 KiB
C
513 lines
13 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/config.h>
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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 "rtmutex_common.h"
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#ifdef CONFIG_DEBUG_RT_MUTEXES
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# include "rtmutex-debug.h"
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#else
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# include "rtmutex.h"
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#endif
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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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if (spin_is_locked(¤t->held_list_lock)) \
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spin_unlock(¤t->held_list_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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int rt_trace_on = 1;
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void deadlock_trace_off(void)
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{
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rt_trace_on = 0;
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}
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static void printk_task(task_t *p)
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{
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if (p)
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printk("%16s:%5d [%p, %3d]", p->comm, p->pid, 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_task_short(task_t *p)
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{
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if (p)
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printk("%s/%d [%p, %3d]", p->comm, p->pid, 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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if (rt_mutex_owner(lock)) {
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printk("... acquired at: ");
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print_symbol("%s\n", lock->acquire_ip);
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}
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}
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static void printk_waiter(struct rt_mutex_waiter *w)
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{
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printk("-------------------------\n");
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printk("| waiter struct %p:\n", w);
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printk("| w->list_entry: [DP:%p/%p|SP:%p/%p|PRI:%d]\n",
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w->list_entry.plist.prio_list.prev, w->list_entry.plist.prio_list.next,
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w->list_entry.plist.node_list.prev, w->list_entry.plist.node_list.next,
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w->list_entry.prio);
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printk("| w->pi_list_entry: [DP:%p/%p|SP:%p/%p|PRI:%d]\n",
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w->pi_list_entry.plist.prio_list.prev, w->pi_list_entry.plist.prio_list.next,
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w->pi_list_entry.plist.node_list.prev, w->pi_list_entry.plist.node_list.next,
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w->pi_list_entry.prio);
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printk("\n| lock:\n");
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printk_lock(w->lock, 1);
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printk("| w->ti->task:\n");
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printk_task(w->task);
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printk("| blocked at: ");
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print_symbol("%s\n", w->ip);
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printk("-------------------------\n");
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}
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static void show_task_locks(task_t *p)
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{
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switch (p->state) {
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case TASK_RUNNING: printk("R"); break;
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case TASK_INTERRUPTIBLE: printk("S"); break;
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case TASK_UNINTERRUPTIBLE: printk("D"); break;
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case TASK_STOPPED: printk("T"); break;
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case EXIT_ZOMBIE: printk("Z"); break;
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case EXIT_DEAD: printk("X"); break;
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default: printk("?"); break;
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}
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printk_task(p);
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if (p->pi_blocked_on) {
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struct rt_mutex *lock = p->pi_blocked_on->lock;
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printk(" blocked on:");
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printk_lock(lock, 1);
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} else
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printk(" (not blocked)\n");
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}
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void rt_mutex_show_held_locks(task_t *task, int verbose)
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{
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struct list_head *curr, *cursor = NULL;
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struct rt_mutex *lock;
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task_t *t;
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unsigned long flags;
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int count = 0;
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if (!rt_trace_on)
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return;
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if (verbose) {
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printk("------------------------------\n");
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printk("| showing all locks held by: | (");
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printk_task_short(task);
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printk("):\n");
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printk("------------------------------\n");
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}
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next:
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spin_lock_irqsave(&task->held_list_lock, flags);
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list_for_each(curr, &task->held_list_head) {
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if (cursor && curr != cursor)
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continue;
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lock = list_entry(curr, struct rt_mutex, held_list_entry);
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t = rt_mutex_owner(lock);
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WARN_ON(t != task);
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count++;
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cursor = curr->next;
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spin_unlock_irqrestore(&task->held_list_lock, flags);
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printk("\n#%03d: ", count);
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printk_lock(lock, 0);
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goto next;
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}
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spin_unlock_irqrestore(&task->held_list_lock, flags);
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printk("\n");
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}
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void rt_mutex_show_all_locks(void)
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{
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task_t *g, *p;
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int count = 10;
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int unlock = 1;
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printk("\n");
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printk("----------------------\n");
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printk("| showing all tasks: |\n");
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printk("----------------------\n");
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/*
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* Here we try to get the tasklist_lock as hard as possible,
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* if not successful after 2 seconds we ignore it (but keep
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* trying). This is to enable a debug printout even if a
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* tasklist_lock-holding task deadlocks or crashes.
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*/
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retry:
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if (!read_trylock(&tasklist_lock)) {
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if (count == 10)
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printk("hm, tasklist_lock locked, retrying... ");
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if (count) {
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count--;
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printk(" #%d", 10-count);
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mdelay(200);
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goto retry;
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}
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printk(" ignoring it.\n");
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unlock = 0;
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}
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if (count != 10)
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printk(" locked it.\n");
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do_each_thread(g, p) {
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show_task_locks(p);
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if (!unlock)
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if (read_trylock(&tasklist_lock))
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unlock = 1;
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} while_each_thread(g, p);
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printk("\n");
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printk("-----------------------------------------\n");
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printk("| showing all locks held in the system: |\n");
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printk("-----------------------------------------\n");
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do_each_thread(g, p) {
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rt_mutex_show_held_locks(p, 0);
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if (!unlock)
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if (read_trylock(&tasklist_lock))
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unlock = 1;
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} while_each_thread(g, p);
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printk("=============================================\n\n");
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if (unlock)
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read_unlock(&tasklist_lock);
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}
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void rt_mutex_debug_check_no_locks_held(task_t *task)
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{
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struct rt_mutex_waiter *w;
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struct list_head *curr;
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struct rt_mutex *lock;
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if (!rt_trace_on)
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return;
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if (!rt_prio(task->normal_prio) && rt_prio(task->prio)) {
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printk("BUG: PI priority boost leaked!\n");
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printk_task(task);
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printk("\n");
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}
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if (list_empty(&task->held_list_head))
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return;
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spin_lock(&task->pi_lock);
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plist_for_each_entry(w, &task->pi_waiters, pi_list_entry) {
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TRACE_OFF();
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printk("hm, PI interest held at exit time? Task:\n");
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printk_task(task);
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printk_waiter(w);
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return;
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}
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spin_unlock(&task->pi_lock);
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list_for_each(curr, &task->held_list_head) {
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lock = list_entry(curr, struct rt_mutex, held_list_entry);
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printk("BUG: %s/%d, lock held at task exit time!\n",
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task->comm, task->pid);
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printk_lock(lock, 1);
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if (rt_mutex_owner(lock) != task)
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printk("exiting task is not even the owner??\n");
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}
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}
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int rt_mutex_debug_check_no_locks_freed(const void *from, unsigned long len)
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{
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const void *to = from + len;
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struct list_head *curr;
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struct rt_mutex *lock;
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unsigned long flags;
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void *lock_addr;
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if (!rt_trace_on)
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return 0;
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spin_lock_irqsave(¤t->held_list_lock, flags);
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list_for_each(curr, ¤t->held_list_head) {
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lock = list_entry(curr, struct rt_mutex, held_list_entry);
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lock_addr = lock;
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if (lock_addr < from || lock_addr >= to)
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continue;
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TRACE_OFF();
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printk("BUG: %s/%d, active lock [%p(%p-%p)] freed!\n",
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current->comm, current->pid, lock, from, to);
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dump_stack();
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printk_lock(lock, 1);
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if (rt_mutex_owner(lock) != current)
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printk("freeing task is not even the owner??\n");
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return 1;
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}
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spin_unlock_irqrestore(¤t->held_list_lock, flags);
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return 0;
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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 = task->pid;
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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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task = find_task_by_pid(waiter->deadlock_task_pid);
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if (!task)
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return;
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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, current->comm, current->pid);
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printk("\n1) %s/%d is trying to acquire this lock:\n",
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current->comm, current->pid);
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printk_lock(waiter->lock, 1);
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printk("... trying at: ");
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print_symbol("%s\n", waiter->ip);
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printk("\n2) %s/%d is blocked on this lock:\n", task->comm, task->pid);
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printk_lock(waiter->deadlock_lock, 1);
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rt_mutex_show_held_locks(current, 1);
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rt_mutex_show_held_locks(task, 1);
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printk("\n%s/%d's [blocked] stackdump:\n\n", task->comm, task->pid);
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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, current->pid);
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dump_stack();
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rt_mutex_show_all_locks();
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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 __IP_DECL__)
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{
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unsigned long flags;
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if (rt_trace_on) {
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TRACE_WARN_ON_LOCKED(!list_empty(&lock->held_list_entry));
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spin_lock_irqsave(¤t->held_list_lock, flags);
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list_add_tail(&lock->held_list_entry, ¤t->held_list_head);
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spin_unlock_irqrestore(¤t->held_list_lock, flags);
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lock->acquire_ip = ip;
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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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unsigned long flags;
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if (rt_trace_on) {
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TRACE_WARN_ON_LOCKED(rt_mutex_owner(lock) != current);
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TRACE_WARN_ON_LOCKED(list_empty(&lock->held_list_entry));
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spin_lock_irqsave(¤t->held_list_lock, flags);
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list_del_init(&lock->held_list_entry);
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spin_unlock_irqrestore(¤t->held_list_lock, flags);
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}
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}
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void debug_rt_mutex_proxy_lock(struct rt_mutex *lock,
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struct task_struct *powner __IP_DECL__)
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{
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unsigned long flags;
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if (rt_trace_on) {
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TRACE_WARN_ON_LOCKED(!list_empty(&lock->held_list_entry));
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spin_lock_irqsave(&powner->held_list_lock, flags);
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list_add_tail(&lock->held_list_entry, &powner->held_list_head);
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spin_unlock_irqrestore(&powner->held_list_lock, flags);
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lock->acquire_ip = ip;
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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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unsigned long flags;
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if (rt_trace_on) {
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struct task_struct *owner = rt_mutex_owner(lock);
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TRACE_WARN_ON_LOCKED(!owner);
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TRACE_WARN_ON_LOCKED(list_empty(&lock->held_list_entry));
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spin_lock_irqsave(&owner->held_list_lock, flags);
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list_del_init(&lock->held_list_entry);
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spin_unlock_irqrestore(&owner->held_list_lock, flags);
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}
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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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}
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void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
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{
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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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void *addr = lock;
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if (rt_trace_on) {
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rt_mutex_debug_check_no_locks_freed(addr,
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sizeof(struct rt_mutex));
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INIT_LIST_HEAD(&lock->held_list_entry);
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lock->name = name;
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}
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}
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void rt_mutex_deadlock_account_lock(struct rt_mutex *lock, task_t *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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