Commit e7eebaf6 authored by Ingo Molnar's avatar Ingo Molnar Committed by Linus Torvalds
Browse files

[PATCH] pi-futex: rt mutex debug



Runtime debugging functionality for rt-mutexes.
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent a6537be9
......@@ -1034,6 +1034,7 @@ static inline void
debug_check_no_locks_freed(const void *from, unsigned long len)
{
mutex_debug_check_no_locks_freed(from, len);
rt_mutex_debug_check_no_locks_freed(from, len);
}
#ifndef CONFIG_DEBUG_PAGEALLOC
......
......@@ -40,6 +40,19 @@ struct rt_mutex {
struct rt_mutex_waiter;
struct hrtimer_sleeper;
#ifdef CONFIG_DEBUG_RT_MUTEXES
extern int rt_mutex_debug_check_no_locks_freed(const void *from,
unsigned long len);
extern void rt_mutex_debug_check_no_locks_held(struct task_struct *task);
#else
static inline int rt_mutex_debug_check_no_locks_freed(const void *from,
unsigned long len)
{
return 0;
}
# define rt_mutex_debug_check_no_locks_held(task) do { } while (0)
#endif
#ifdef CONFIG_DEBUG_RT_MUTEXES
# define __DEBUG_RT_MUTEX_INITIALIZER(mutexname) \
, .name = #mutexname, .file = __FILE__, .line = __LINE__
......@@ -48,7 +61,7 @@ struct hrtimer_sleeper;
#else
# define __DEBUG_RT_MUTEX_INITIALIZER(mutexname)
# define rt_mutex_init(mutex) __rt_mutex_init(mutex, NULL)
# define rt_mutex_debug_task_free(t) do { } while (0)
# define rt_mutex_debug_task_free(t) do { } while (0)
#endif
#define __RT_MUTEX_INITIALIZER(mutexname) \
......
......@@ -17,6 +17,7 @@ ifeq ($(CONFIG_COMPAT),y)
obj-$(CONFIG_FUTEX) += futex_compat.o
endif
obj-$(CONFIG_RT_MUTEXES) += rtmutex.o
obj-$(CONFIG_DEBUG_RT_MUTEXES) += rtmutex-debug.o
obj-$(CONFIG_GENERIC_ISA_DMA) += dma.o
obj-$(CONFIG_SMP) += cpu.o spinlock.o
obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock.o
......
......@@ -929,6 +929,7 @@ fastcall NORET_TYPE void do_exit(long code)
* If DEBUG_MUTEXES is on, make sure we are holding no locks:
*/
mutex_debug_check_no_locks_held(tsk);
rt_mutex_debug_check_no_locks_held(tsk);
if (tsk->io_context)
exit_io_context();
......
/*
* 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(&current->pi_lock)) \
spin_unlock(&current->pi_lock); \
if (spin_is_locked(&current->held_list_lock)) \
spin_unlock(&current->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->prio)) {
printk("BUG: PI priority boost leaked!\n");
printk_task(task);
printk("\n");
}
if (list_empty(&task->held_list_head))
return;
spin_lock(&task->pi_lock);
plist_for_each_entry(w, &task->pi_waiters, pi_list_entry) {
TRACE_OFF();
printk("hm, PI interest held at exit time? Task:\n");
printk_task(task);
printk_waiter(w);
return;
}
spin_unlock(&task->pi_lock);
list_for_each(curr, &task->held_list_head) {
lock = list_entry(curr, struct rt_mutex, held_list_entry);
printk("BUG: %s/%d, lock held at task exit time!\n",
task->comm, task->pid);
printk_lock(lock, 1);
if (rt_mutex_owner(lock) != task)
printk("exiting task is not even the owner??\n");
}
}
int rt_mutex_debug_check_no_locks_freed(const void *from, unsigned long len)
{
const void *to = from + len;
struct list_head *curr;
struct rt_mutex *lock;
unsigned long flags;
void *lock_addr;
if (!rt_trace_on)
return 0;
spin_lock_irqsave(&current->held_list_lock, flags);
list_for_each(curr, &current->held_list_head) {
lock = list_entry(curr, struct rt_mutex, held_list_entry);
lock_addr = lock;
if (lock_addr < from || lock_addr >= to)
continue;
TRACE_OFF();
printk("BUG: %s/%d, active lock [%p(%p-%p)] freed!\n",
current->comm, current->pid, lock, from, to);
dump_stack();
printk_lock(lock, 1);
if (rt_mutex_owner(lock) != current)
printk("freeing task is not even the owner??\n");
return 1;
}
spin_unlock_irqrestore(&current->held_list_lock, flags);
return 0;
}
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 = task->pid;
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;
task = find_task_by_pid(waiter->deadlock_task_pid);
if (!task)
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, current->comm, current->pid);
printk("\n1) %s/%d is trying to acquire this lock:\n",
current->comm, current->pid);
printk_lock(waiter->lock, 1);
printk("... trying at: ");
print_symbol("%s\n", waiter->ip);
printk("\n2) %s/%d is blocked on this lock:\n", task->comm, task->pid);
printk_lock(waiter->deadlock_lock, 1);
rt_mutex_show_held_locks(current, 1);
rt_mutex_show_held_locks(task, 1);
printk("\n%s/%d's [blocked] stackdump:\n\n", task->comm, task->pid);
show_stack(task, NULL);
printk("\n%s/%d's [current] stackdump:\n\n",
current->comm, current->pid);
dump_stack();
rt_mutex_show_all_locks();
printk("[ turning off deadlock detection."
"Please report this trace. ]\n\n");
local_irq_disable();
}
void debug_rt_mutex_lock(struct rt_mutex *lock __IP_DECL__)
{
unsigned long flags;
if (rt_trace_on) {
TRACE_WARN_ON_LOCKED(!list_empty(&lock->held_list_entry));
spin_lock_irqsave(&current->held_list_lock, flags);
list_add_tail(&lock->held_list_entry, &current->held_list_head);
spin_unlock_irqrestore(&current->held_list_lock, flags);
lock->acquire_ip = ip;
}
}
void debug_rt_mutex_unlock(struct rt_mutex *lock)
{
unsigned long flags;
if (rt_trace_on) {
TRACE_WARN_ON_LOCKED(rt_mutex_owner(lock) != current);
TRACE_WARN_ON_LOCKED(list_empty(&lock->held_list_entry));
spin_lock_irqsave(&current->held_list_lock, flags);
list_del_init(&lock->held_list_entry);
spin_unlock_irqrestore(&current->held_list_lock, flags);
}
}
void debug_rt_mutex_proxy_lock(struct rt_mutex *lock,
struct task_struct *powner __IP_DECL__)
{
unsigned long flags;
if (rt_trace_on) {
TRACE_WARN_ON_LOCKED(!list_empty(&lock->held_list_entry));
spin_lock_irqsave(&powner->held_list_lock, flags);
list_add_tail(&lock->held_list_entry, &powner->held_list_head);
spin_unlock_irqrestore(&powner->held_list_lock, flags);
lock->acquire_ip = ip;
}
}
void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock)
{
unsigned long flags;
if (rt_trace_on) {
struct task_struct *owner = rt_mutex_owner(lock);
TRACE_WARN_ON_LOCKED(!owner);
TRACE_WARN_ON_LOCKED(list_empty(&lock->held_list_entry));
spin_lock_irqsave(&owner->held_list_lock, flags);
list_del_init(&lock->held_list_entry);
spin_unlock_irqrestore(&owner->held_list_lock, flags);
}
}
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);
}
void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
{
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)
{
void *addr = lock;
if (rt_trace_on) {
rt_mutex_debug_check_no_locks_freed(addr,
sizeof(struct rt_mutex));
INIT_LIST_HEAD(&lock->held_list_entry);
lock->name = name;
}
}
void rt_mutex_deadlock_account_lock(struct rt_mutex *lock, task_t *task)
{
}
void rt_mutex_deadlock_account_unlock(struct task_struct *task)
{
}
/*
* 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 file contains macros used solely by rtmutex.c. Debug version.
*/
#define __IP_DECL__ , unsigned long ip
#define __IP__ , ip
#define __RET_IP__ , (unsigned long)__builtin_return_address(0)
extern void
rt_mutex_deadlock_account_lock(struct rt_mutex *lock, struct task_struct *task);
extern void rt_mutex_deadlock_account_unlock(struct task_struct *task);
extern void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter);
extern void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter);
extern void debug_rt_mutex_init(struct rt_mutex *lock, const char *name);
extern void debug_rt_mutex_lock(struct rt_mutex *lock __IP_DECL__);
extern void debug_rt_mutex_unlock(struct rt_mutex *lock);
extern void debug_rt_mutex_proxy_lock(struct rt_mutex *lock,
struct task_struct *powner __IP_DECL__);
extern void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock);
extern void debug_rt_mutex_deadlock(int detect, struct rt_mutex_waiter *waiter,
struct rt_mutex *lock);
extern void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter);
# define debug_rt_mutex_reset_waiter(w) \
do { (w)->deadlock_lock = NULL; } while (0)
static inline int debug_rt_mutex_detect_deadlock(struct rt_mutex_waiter *waiter,
int detect)
{
return (waiter != NULL);
}
......@@ -107,6 +107,19 @@ config DEBUG_MUTEXES
This allows mutex semantics violations and mutex related deadlocks
(lockups) to be detected and reported automatically.
config DEBUG_RT_MUTEXES
bool "RT Mutex debugging, deadlock detection"
default y
depends on DEBUG_KERNEL && RT_MUTEXES
help
This allows rt mutex semantics violations and rt mutex related
deadlocks (lockups) to be detected and reported automatically.