[PATCH] lockdep: better lock debugging
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>
diff --git a/kernel/rtmutex-debug.c b/kernel/rtmutex-debug.c
index 4aa8a2c9..353a853 100644
--- a/kernel/rtmutex-debug.c
+++ b/kernel/rtmutex-debug.c
@@ -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 @@
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)
@@ -105,14 +104,6 @@
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 @@
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(¤t->held_list_lock, flags);
- list_for_each(curr, ¤t->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(¤t->held_list_lock, flags);
-
- return 0;
}
void rt_mutex_debug_task_free(struct task_struct *task)
@@ -395,85 +170,41 @@
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(¤t->held_list_lock, flags);
- list_add_tail(&lock->held_list_entry, ¤t->held_list_head);
- spin_unlock_irqrestore(¤t->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(¤t->held_list_lock, flags);
- list_del_init(&lock->held_list_entry);
- spin_unlock_irqrestore(¤t->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_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)