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Diffstat (limited to 'kernel/lockdep.c')
-rw-r--r--kernel/lockdep.c240
1 files changed, 194 insertions, 46 deletions
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 91d67ce3a8d5..e69434b070da 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -96,8 +96,13 @@ static int graph_lock(void)
static inline int graph_unlock(void)
{
- if (debug_locks && !arch_spin_is_locked(&lockdep_lock))
+ if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {
+ /*
+ * The lockdep graph lock isn't locked while we expect it to
+ * be, we're confused now, bye!
+ */
return DEBUG_LOCKS_WARN_ON(1);
+ }
current->lockdep_recursion--;
arch_spin_unlock(&lockdep_lock);
@@ -134,6 +139,9 @@ static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
static inline struct lock_class *hlock_class(struct held_lock *hlock)
{
if (!hlock->class_idx) {
+ /*
+ * Someone passed in garbage, we give up.
+ */
DEBUG_LOCKS_WARN_ON(1);
return NULL;
}
@@ -687,6 +695,10 @@ look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
*/
list_for_each_entry(class, hash_head, hash_entry) {
if (class->key == key) {
+ /*
+ * Huh! same key, different name? Did someone trample
+ * on some memory? We're most confused.
+ */
WARN_ON_ONCE(class->name != lock->name);
return class;
}
@@ -800,6 +812,10 @@ out_unlock_set:
else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
lock->class_cache[subclass] = class;
+ /*
+ * Hash collision, did we smoke some? We found a class with a matching
+ * hash but the subclass -- which is hashed in -- didn't match.
+ */
if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
return NULL;
@@ -926,7 +942,7 @@ static inline void mark_lock_accessed(struct lock_list *lock,
unsigned long nr;
nr = lock - list_entries;
- WARN_ON(nr >= nr_list_entries);
+ WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
lock->parent = parent;
lock->class->dep_gen_id = lockdep_dependency_gen_id;
}
@@ -936,7 +952,7 @@ static inline unsigned long lock_accessed(struct lock_list *lock)
unsigned long nr;
nr = lock - list_entries;
- WARN_ON(nr >= nr_list_entries);
+ WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
return lock->class->dep_gen_id == lockdep_dependency_gen_id;
}
@@ -1129,10 +1145,11 @@ print_circular_bug_header(struct lock_list *entry, unsigned int depth,
if (debug_locks_silent)
return 0;
- printk("\n=======================================================\n");
- printk( "[ INFO: possible circular locking dependency detected ]\n");
+ printk("\n");
+ printk("======================================================\n");
+ printk("[ INFO: possible circular locking dependency detected ]\n");
print_kernel_version();
- printk( "-------------------------------------------------------\n");
+ printk("-------------------------------------------------------\n");
printk("%s/%d is trying to acquire lock:\n",
curr->comm, task_pid_nr(curr));
print_lock(check_src);
@@ -1196,6 +1213,9 @@ static noinline int print_bfs_bug(int ret)
if (!debug_locks_off_graph_unlock())
return 0;
+ /*
+ * Breadth-first-search failed, graph got corrupted?
+ */
WARN(1, "lockdep bfs error:%d\n", ret);
return 0;
@@ -1463,11 +1483,12 @@ print_bad_irq_dependency(struct task_struct *curr,
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
return 0;
- printk("\n======================================================\n");
- printk( "[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
+ printk("\n");
+ printk("======================================================\n");
+ printk("[ INFO: %s-safe -> %s-unsafe lock order detected ]\n",
irqclass, irqclass);
print_kernel_version();
- printk( "------------------------------------------------------\n");
+ printk("------------------------------------------------------\n");
printk("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
curr->comm, task_pid_nr(curr),
curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
@@ -1692,10 +1713,11 @@ print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
return 0;
- printk("\n=============================================\n");
- printk( "[ INFO: possible recursive locking detected ]\n");
+ printk("\n");
+ printk("=============================================\n");
+ printk("[ INFO: possible recursive locking detected ]\n");
print_kernel_version();
- printk( "---------------------------------------------\n");
+ printk("---------------------------------------------\n");
printk("%s/%d is trying to acquire lock:\n",
curr->comm, task_pid_nr(curr));
print_lock(next);
@@ -1944,6 +1966,11 @@ out_bug:
if (!debug_locks_off_graph_unlock())
return 0;
+ /*
+ * Clearly we all shouldn't be here, but since we made it we
+ * can reliable say we messed up our state. See the above two
+ * gotos for reasons why we could possibly end up here.
+ */
WARN_ON(1);
return 0;
@@ -1975,6 +2002,11 @@ static inline int lookup_chain_cache(struct task_struct *curr,
struct held_lock *hlock_curr, *hlock_next;
int i, j;
+ /*
+ * We might need to take the graph lock, ensure we've got IRQs
+ * disabled to make this an IRQ-safe lock.. for recursion reasons
+ * lockdep won't complain about its own locking errors.
+ */
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
return 0;
/*
@@ -2126,6 +2158,10 @@ static void check_chain_key(struct task_struct *curr)
hlock = curr->held_locks + i;
if (chain_key != hlock->prev_chain_key) {
debug_locks_off();
+ /*
+ * We got mighty confused, our chain keys don't match
+ * with what we expect, someone trample on our task state?
+ */
WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
curr->lockdep_depth, i,
(unsigned long long)chain_key,
@@ -2133,6 +2169,9 @@ static void check_chain_key(struct task_struct *curr)
return;
}
id = hlock->class_idx - 1;
+ /*
+ * Whoops ran out of static storage again?
+ */
if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
return;
@@ -2144,6 +2183,10 @@ static void check_chain_key(struct task_struct *curr)
}
if (chain_key != curr->curr_chain_key) {
debug_locks_off();
+ /*
+ * More smoking hash instead of calculating it, damn see these
+ * numbers float.. I bet that a pink elephant stepped on my memory.
+ */
WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
curr->lockdep_depth, i,
(unsigned long long)chain_key,
@@ -2177,10 +2220,11 @@ print_usage_bug(struct task_struct *curr, struct held_lock *this,
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
return 0;
- printk("\n=================================\n");
- printk( "[ INFO: inconsistent lock state ]\n");
+ printk("\n");
+ printk("=================================\n");
+ printk("[ INFO: inconsistent lock state ]\n");
print_kernel_version();
- printk( "---------------------------------\n");
+ printk("---------------------------------\n");
printk("inconsistent {%s} -> {%s} usage.\n",
usage_str[prev_bit], usage_str[new_bit]);
@@ -2241,10 +2285,11 @@ print_irq_inversion_bug(struct task_struct *curr,
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
return 0;
- printk("\n=========================================================\n");
- printk( "[ INFO: possible irq lock inversion dependency detected ]\n");
+ printk("\n");
+ printk("=========================================================\n");
+ printk("[ INFO: possible irq lock inversion dependency detected ]\n");
print_kernel_version();
- printk( "---------------------------------------------------------\n");
+ printk("---------------------------------------------------------\n");
printk("%s/%d just changed the state of lock:\n",
curr->comm, task_pid_nr(curr));
print_lock(this);
@@ -2525,12 +2570,24 @@ void trace_hardirqs_on_caller(unsigned long ip)
return;
}
+ /*
+ * We're enabling irqs and according to our state above irqs weren't
+ * already enabled, yet we find the hardware thinks they are in fact
+ * enabled.. someone messed up their IRQ state tracing.
+ */
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
return;
+ /*
+ * See the fine text that goes along with this variable definition.
+ */
if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
return;
+ /*
+ * Can't allow enabling interrupts while in an interrupt handler,
+ * that's general bad form and such. Recursion, limited stack etc..
+ */
if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
return;
@@ -2558,6 +2615,10 @@ void trace_hardirqs_off_caller(unsigned long ip)
if (unlikely(!debug_locks || current->lockdep_recursion))
return;
+ /*
+ * So we're supposed to get called after you mask local IRQs, but for
+ * some reason the hardware doesn't quite think you did a proper job.
+ */
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
return;
@@ -2590,6 +2651,10 @@ void trace_softirqs_on(unsigned long ip)
if (unlikely(!debug_locks || current->lockdep_recursion))
return;
+ /*
+ * We fancy IRQs being disabled here, see softirq.c, avoids
+ * funny state and nesting things.
+ */
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
return;
@@ -2626,6 +2691,9 @@ void trace_softirqs_off(unsigned long ip)
if (unlikely(!debug_locks || current->lockdep_recursion))
return;
+ /*
+ * We fancy IRQs being disabled here, see softirq.c
+ */
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
return;
@@ -2637,6 +2705,9 @@ void trace_softirqs_off(unsigned long ip)
curr->softirq_disable_ip = ip;
curr->softirq_disable_event = ++curr->irq_events;
debug_atomic_inc(softirqs_off_events);
+ /*
+ * Whoops, we wanted softirqs off, so why aren't they?
+ */
DEBUG_LOCKS_WARN_ON(!softirq_count());
} else
debug_atomic_inc(redundant_softirqs_off);
@@ -2661,6 +2732,9 @@ static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
if (!(gfp_mask & __GFP_FS))
return;
+ /*
+ * Oi! Can't be having __GFP_FS allocations with IRQs disabled.
+ */
if (DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)))
return;
@@ -2773,13 +2847,13 @@ static int separate_irq_context(struct task_struct *curr,
return 0;
}
-#else
+#else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
static inline
int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
enum lock_usage_bit new_bit)
{
- WARN_ON(1);
+ WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
return 1;
}
@@ -2799,7 +2873,7 @@ void lockdep_trace_alloc(gfp_t gfp_mask)
{
}
-#endif
+#endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
/*
* Mark a lock with a usage bit, and validate the state transition:
@@ -2880,6 +2954,9 @@ void lockdep_init_map(struct lockdep_map *lock, const char *name,
lock->cpu = raw_smp_processor_id();
#endif
+ /*
+ * Can't be having no nameless bastards around this place!
+ */
if (DEBUG_LOCKS_WARN_ON(!name)) {
lock->name = "NULL";
return;
@@ -2887,6 +2964,9 @@ void lockdep_init_map(struct lockdep_map *lock, const char *name,
lock->name = name;
+ /*
+ * No key, no joy, we need to hash something.
+ */
if (DEBUG_LOCKS_WARN_ON(!key))
return;
/*
@@ -2894,6 +2974,9 @@ void lockdep_init_map(struct lockdep_map *lock, const char *name,
*/
if (!static_obj(key)) {
printk("BUG: key %p not in .data!\n", key);
+ /*
+ * What it says above ^^^^^, I suggest you read it.
+ */
DEBUG_LOCKS_WARN_ON(1);
return;
}
@@ -2932,6 +3015,11 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
if (unlikely(!debug_locks))
return 0;
+ /*
+ * Lockdep should run with IRQs disabled, otherwise we could
+ * get an interrupt which would want to take locks, which would
+ * end up in lockdep and have you got a head-ache already?
+ */
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
return 0;
@@ -2963,6 +3051,9 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
* dependency checks are done)
*/
depth = curr->lockdep_depth;
+ /*
+ * Ran out of static storage for our per-task lock stack again have we?
+ */
if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
return 0;
@@ -2981,6 +3072,10 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
}
hlock = curr->held_locks + depth;
+ /*
+ * Plain impossible, we just registered it and checked it weren't no
+ * NULL like.. I bet this mushroom I ate was good!
+ */
if (DEBUG_LOCKS_WARN_ON(!class))
return 0;
hlock->class_idx = class_idx;
@@ -3015,11 +3110,17 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
* the hash, not class->key.
*/
id = class - lock_classes;
+ /*
+ * Whoops, we did it again.. ran straight out of our static allocation.
+ */
if (DEBUG_LOCKS_WARN_ON(id >= MAX_LOCKDEP_KEYS))
return 0;
chain_key = curr->curr_chain_key;
if (!depth) {
+ /*
+ * How can we have a chain hash when we ain't got no keys?!
+ */
if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
return 0;
chain_head = 1;
@@ -3065,9 +3166,10 @@ print_unlock_inbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
if (debug_locks_silent)
return 0;
- printk("\n=====================================\n");
- printk( "[ BUG: bad unlock balance detected! ]\n");
- printk( "-------------------------------------\n");
+ printk("\n");
+ printk("=====================================\n");
+ printk("[ BUG: bad unlock balance detected! ]\n");
+ printk("-------------------------------------\n");
printk("%s/%d is trying to release lock (",
curr->comm, task_pid_nr(curr));
print_lockdep_cache(lock);
@@ -3091,6 +3193,9 @@ static int check_unlock(struct task_struct *curr, struct lockdep_map *lock,
{
if (unlikely(!debug_locks))
return 0;
+ /*
+ * Lockdep should run with IRQs disabled, recursion, head-ache, etc..
+ */
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
return 0;
@@ -3120,6 +3225,11 @@ static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
if (!class)
return 0;
+ /*
+ * References, but not a lock we're actually ref-counting?
+ * State got messed up, follow the sites that change ->references
+ * and try to make sense of it.
+ */
if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
return 0;
@@ -3142,6 +3252,10 @@ __lock_set_class(struct lockdep_map *lock, const char *name,
int i;
depth = curr->lockdep_depth;
+ /*
+ * This function is about (re)setting the class of a held lock,
+ * yet we're not actually holding any locks. Naughty user!
+ */
if (DEBUG_LOCKS_WARN_ON(!depth))
return 0;
@@ -3177,6 +3291,10 @@ found_it:
return 0;
}
+ /*
+ * I took it apart and put it back together again, except now I have
+ * these 'spare' parts.. where shall I put them.
+ */
if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
return 0;
return 1;
@@ -3201,6 +3319,10 @@ lock_release_non_nested(struct task_struct *curr,
* of held locks:
*/
depth = curr->lockdep_depth;
+ /*
+ * So we're all set to release this lock.. wait what lock? We don't
+ * own any locks, you've been drinking again?
+ */
if (DEBUG_LOCKS_WARN_ON(!depth))
return 0;
@@ -3253,6 +3375,10 @@ found_it:
return 0;
}
+ /*
+ * We had N bottles of beer on the wall, we drank one, but now
+ * there's not N-1 bottles of beer left on the wall...
+ */
if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
return 0;
return 1;
@@ -3283,6 +3409,9 @@ static int lock_release_nested(struct task_struct *curr,
return lock_release_non_nested(curr, lock, ip);
curr->lockdep_depth--;
+ /*
+ * No more locks, but somehow we've got hash left over, who left it?
+ */
if (DEBUG_LOCKS_WARN_ON(!depth && (hlock->prev_chain_key != 0)))
return 0;
@@ -3365,10 +3494,13 @@ static void check_flags(unsigned long flags)
* check if not in hardirq contexts:
*/
if (!hardirq_count()) {
- if (softirq_count())
+ if (softirq_count()) {
+ /* like the above, but with softirqs */
DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
- else
+ } else {
+ /* lick the above, does it taste good? */
DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
+ }
}
if (!debug_locks)
@@ -3478,9 +3610,10 @@ print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
if (debug_locks_silent)
return 0;
- printk("\n=================================\n");
- printk( "[ BUG: bad contention detected! ]\n");
- printk( "---------------------------------\n");
+ printk("\n");
+ printk("=================================\n");
+ printk("[ BUG: bad contention detected! ]\n");
+ printk("---------------------------------\n");
printk("%s/%d is trying to contend lock (",
curr->comm, task_pid_nr(curr));
print_lockdep_cache(lock);
@@ -3506,6 +3639,10 @@ __lock_contended(struct lockdep_map *lock, unsigned long ip)
int i, contention_point, contending_point;
depth = curr->lockdep_depth;
+ /*
+ * Whee, we contended on this lock, except it seems we're not
+ * actually trying to acquire anything much at all..
+ */
if (DEBUG_LOCKS_WARN_ON(!depth))
return;
@@ -3555,6 +3692,10 @@ __lock_acquired(struct lockdep_map *lock, unsigned long ip)
int i, cpu;
depth = curr->lockdep_depth;
+ /*
+ * Yay, we acquired ownership of this lock we didn't try to
+ * acquire, how the heck did that happen?
+ */
if (DEBUG_LOCKS_WARN_ON(!depth))
return;
@@ -3759,8 +3900,12 @@ void lockdep_reset_lock(struct lockdep_map *lock)
match |= class == lock->class_cache[j];
if (unlikely(match)) {
- if (debug_locks_off_graph_unlock())
+ if (debug_locks_off_graph_unlock()) {
+ /*
+ * We all just reset everything, how did it match?
+ */
WARN_ON(1);
+ }
goto out_restore;
}
}
@@ -3839,9 +3984,10 @@ print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
if (debug_locks_silent)
return;
- printk("\n=========================\n");
- printk( "[ BUG: held lock freed! ]\n");
- printk( "-------------------------\n");
+ printk("\n");
+ printk("=========================\n");
+ printk("[ BUG: held lock freed! ]\n");
+ printk("-------------------------\n");
printk("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
print_lock(hlock);
@@ -3895,9 +4041,10 @@ static void print_held_locks_bug(struct task_struct *curr)
if (debug_locks_silent)
return;
- printk("\n=====================================\n");
- printk( "[ BUG: lock held at task exit time! ]\n");
- printk( "-------------------------------------\n");
+ printk("\n");
+ printk("=====================================\n");
+ printk("[ BUG: lock held at task exit time! ]\n");
+ printk("-------------------------------------\n");
printk("%s/%d is exiting with locks still held!\n",
curr->comm, task_pid_nr(curr));
lockdep_print_held_locks(curr);
@@ -3991,16 +4138,17 @@ void lockdep_sys_exit(void)
if (unlikely(curr->lockdep_depth)) {
if (!debug_locks_off())
return;
- printk("\n================================================\n");
- printk( "[ BUG: lock held when returning to user space! ]\n");
- printk( "------------------------------------------------\n");
+ printk("\n");
+ printk("================================================\n");
+ printk("[ BUG: lock held when returning to user space! ]\n");
+ printk("------------------------------------------------\n");
printk("%s/%d is leaving the kernel with locks still held!\n",
curr->comm, curr->pid);
lockdep_print_held_locks(curr);
}
}
-void lockdep_rcu_dereference(const char *file, const int line)
+void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
{
struct task_struct *curr = current;
@@ -4009,15 +4157,15 @@ void lockdep_rcu_dereference(const char *file, const int line)
return;
#endif /* #ifdef CONFIG_PROVE_RCU_REPEATEDLY */
/* Note: the following can be executed concurrently, so be careful. */
- printk("\n===================================================\n");
- printk( "[ INFO: suspicious rcu_dereference_check() usage. ]\n");
- printk( "---------------------------------------------------\n");
- printk("%s:%d invoked rcu_dereference_check() without protection!\n",
- file, line);
+ printk("\n");
+ printk("===============================\n");
+ printk("[ INFO: suspicious RCU usage. ]\n");
+ printk("-------------------------------\n");
+ printk("%s:%d %s!\n", file, line, s);
printk("\nother info that might help us debug this:\n\n");
printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks);
lockdep_print_held_locks(curr);
printk("\nstack backtrace:\n");
dump_stack();
}
-EXPORT_SYMBOL_GPL(lockdep_rcu_dereference);
+EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-18 04:32:03 +0000