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[PATCH] lockdep: better lock debugging

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Generic lock debugging:

 - generalized lock debugging framework. For example, a bug in one lock
   subsystem turns off debugging in all lock subsystems.

 - got rid of the caller address passing (__IP__/__IP_DECL__/etc.) from
   the mutex/rtmutex debugging code: it caused way too much prototype
   hackery, and lockdep will give the same information anyway.

 - ability to do silent tests

 - check lock freeing in vfree too.

 - more finegrained debugging options, to allow distributions to
   turn off more expensive debugging features.

There's no separate 'held mutexes' list anymore - but there's a 'held locks'
stack within lockdep, which unifies deadlock detection across all lock
classes.  (this is independent of the lockdep validation stuff - lockdep first
checks whether we are holding a lock already)

Here are the current debugging options:

CONFIG_DEBUG_MUTEXES=y
CONFIG_DEBUG_LOCK_ALLOC=y

which do:

 config DEBUG_MUTEXES
          bool "Mutex debugging, basic checks"

 config DEBUG_LOCK_ALLOC
         bool "Detect incorrect freeing of live mutexes"

Signed-off-by: Ingo Molnar <mingo@elte.hu>
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>
This commit is contained in:
Ingo Molnar 2006-07-03 00:24:33 -07:00 • committed by Linus Torvalds
parent fb7e42413a
commit 9a11b49a80
25 changed files with 264 additions and 566 deletions
Download patch file Download diff file Expand all files Collapse all files

302
kernel/rtmutex-debug.c
View file

@ -26,6 +26,7 @@
#include <linux/interrupt.h>
#include <linux/plist.h>
#include <linux/fs.h>
#include <linux/debug_locks.h>
#include "rtmutex_common.h"
@ -45,8 +46,6 @@ do { \
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)
@ -105,14 +104,6 @@ static void printk_task(task_t *p)
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)
@ -128,222 +119,6 @@ static void printk_lock(struct rt_mutex *lock, int print_owner)
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)
@ -395,85 +170,41 @@ void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter)
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);
debug_show_held_locks(current);
debug_show_held_locks(task);
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();
debug_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__)
void debug_rt_mutex_lock(struct rt_mutex *lock)
{
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);
}
TRACE_WARN_ON_LOCKED(rt_mutex_owner(lock) != current);
}
void debug_rt_mutex_proxy_lock(struct rt_mutex *lock,
struct task_struct *powner __IP_DECL__)
void
debug_rt_mutex_proxy_lock(struct rt_mutex *lock, struct task_struct *powner)
{
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);
}
TRACE_WARN_ON_LOCKED(!rt_mutex_owner(lock));
}
void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
@ -493,14 +224,11 @@ void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *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;
}
/*
* 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, task_t *task)