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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 <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/config.h>
#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 "rtmutex_common.h"
#ifdef CONFIG_DEBUG_RT_MUTEXES
# include "rtmutex-debug.h"
#else
# include "rtmutex.h"
#endif
# 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(¤t->pi_lock)) \
spin_unlock(¤t->pi_lock); \
if (spin_is_locked(¤t->held_list_lock)) \
spin_unlock(¤t->held_list_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():
*/
int rt_trace_on = 1;
void deadlock_trace_off(void)
{
rt_trace_on = 0;
}
static void printk_task(task_t *p)
{
if (p)
printk("%16s:%5d [%p, %3d]", p->comm, p->pid, p, p->prio);
else
printk("<none>");
}
static void printk_task_short(task_t *p)
{
if (p)
printk("%s/%d [%p, %3d]", p->comm, p->pid, 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");
}
if (rt_mutex_owner(lock)) {
printk("... acquired at: ");
print_symbol("%s\n", lock->acquire_ip);
}
}
static void printk_waiter(struct rt_mutex_waiter *w)
{
printk("-------------------------\n");
printk("| waiter struct %p:\n", w);
printk("| w->list_entry: [DP:%p/%p|SP:%p/%p|PRI:%d]\n",
w->list_entry.plist.prio_list.prev, w->list_entry.plist.prio_list.next,
w->list_entry.plist.node_list.prev, w->list_entry.plist.node_list.next,
w->list_entry.prio);
printk("| w->pi_list_entry: [DP:%p/%p|SP:%p/%p|PRI:%d]\n",
w->pi_list_entry.plist.prio_list.prev, w->pi_list_entry.plist.prio_list.next,
w->pi_list_entry.plist.node_list.prev, w->pi_list_entry.plist.node_list.next,
w->pi_list_entry.prio);
printk("\n| lock:\n");
printk_lock(w->lock, 1);
printk("| w->ti->task:\n");
printk_task(w->task);
printk("| blocked at: ");
print_symbol("%s\n", w->ip);
printk("-------------------------\n");
}
static void show_task_locks(task_t *p)
{
switch (p->state) {
case TASK_RUNNING: printk("R"); break;
case TASK_INTERRUPTIBLE: printk("S"); break;
case TASK_UNINTERRUPTIBLE: printk("D"); break;
case TASK_STOPPED: printk("T"); break;
case EXIT_ZOMBIE: printk("Z"); break;
case EXIT_DEAD: printk("X"); break;
default: printk("?"); break;
}
printk_task(p);
if (p->pi_blocked_on) {
struct rt_mutex *lock = p->pi_blocked_on->lock;
printk(" blocked on:");
printk_lock(lock, 1);
} else
printk(" (not blocked)\n");
}
void rt_mutex_show_held_locks(task_t *task, int verbose)
{
struct list_head *curr, *cursor = NULL;
struct rt_mutex *lock;
task_t *t;
unsigned long flags;
int count = 0;
if (!rt_trace_on)
return;
if (verbose) {
printk("------------------------------\n");
printk("| showing all locks held by: | (");
printk_task_short(task);
printk("):\n");
printk("------------------------------\n");
}
next:
spin_lock_irqsave(&task->held_list_lock, flags);
list_for_each(curr, &task->held_list_head) {
if (cursor && curr != cursor)
continue;
lock = list_entry(curr, struct rt_mutex, held_list_entry);
t = rt_mutex_owner(lock);
WARN_ON(t != task);
count++;
cursor = curr->next;
spin_unlock_irqrestore(&task->held_list_lock, flags);
printk("\n#%03d: ", count);
printk_lock(lock, 0);
goto next;
}
spin_unlock_irqrestore(&task->held_list_lock, flags);
printk("\n");
}
void rt_mutex_show_all_locks(void)
{
task_t *g, *p;
int count = 10;
int unlock = 1;
printk("\n");
printk("----------------------\n");
printk("| showing all tasks: |\n");
printk("----------------------\n");
/*
* Here we try to get the tasklist_lock as hard as possible,
* if not successful after 2 seconds we ignore it (but keep
* trying). This is to enable a debug printout even if a
* tasklist_lock-holding task deadlocks or crashes.
*/
retry:
if (!read_trylock(&tasklist_lock)) {
if (count == 10)
printk("hm, tasklist_lock locked, retrying... ");
if (count) {
count--;
printk(" #%d", 10-count);
mdelay(200);
goto retry;
}
printk(" ignoring it.\n");
unlock = 0;
}
if (count != 10)
printk(" locked it.\n");
do_each_thread(g, p) {
show_task_locks(p);
if (!unlock)
if (read_trylock(&tasklist_lock))
unlock = 1;
} while_each_thread(g, p);
printk("\n");
printk("-----------------------------------------\n");
printk("| showing all locks held in the system: |\n");
printk("-----------------------------------------\n");
do_each_thread(g, p) {
rt_mutex_show_held_locks(p, 0);
if (!unlock)
if (read_trylock(&tasklist_lock))
unlock = 1;
} while_each_thread(g, p);
printk("=============================================\n\n");
if (unlock)
read_unlock(&tasklist_lock);
}
void rt_mutex_debug_check_no_locks_held(task_t *task)
{
struct rt_mutex_waiter *w;
struct list_head *curr;
struct rt_mutex *lock;
if (!rt_trace_on)
return;
if (!rt_prio(task->normal_prio) && rt_prio(task->
|