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-rw-r--r--kernel/lockdep.c245
1 files changed, 143 insertions, 102 deletions
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index c9fefdb1a7d..509efd49540 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -43,13 +43,49 @@
#include "lockdep_internals.h"
/*
- * hash_lock: protects the lockdep hashes and class/list/hash allocators.
+ * lockdep_lock: protects the lockdep graph, the hashes and the
+ * class/list/hash allocators.
*
* This is one of the rare exceptions where it's justified
* to use a raw spinlock - we really dont want the spinlock
- * code to recurse back into the lockdep code.
+ * code to recurse back into the lockdep code...
*/
-static raw_spinlock_t hash_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
+static raw_spinlock_t lockdep_lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
+
+static int graph_lock(void)
+{
+ __raw_spin_lock(&lockdep_lock);
+ /*
+ * Make sure that if another CPU detected a bug while
+ * walking the graph we dont change it (while the other
+ * CPU is busy printing out stuff with the graph lock
+ * dropped already)
+ */
+ if (!debug_locks) {
+ __raw_spin_unlock(&lockdep_lock);
+ return 0;
+ }
+ return 1;
+}
+
+static inline int graph_unlock(void)
+{
+ __raw_spin_unlock(&lockdep_lock);
+ return 0;
+}
+
+/*
+ * Turn lock debugging off and return with 0 if it was off already,
+ * and also release the graph lock:
+ */
+static inline int debug_locks_off_graph_unlock(void)
+{
+ int ret = debug_locks_off();
+
+ __raw_spin_unlock(&lockdep_lock);
+
+ return ret;
+}
static int lockdep_initialized;
@@ -57,14 +93,15 @@ unsigned long nr_list_entries;
static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
/*
- * Allocate a lockdep entry. (assumes hash_lock held, returns
+ * Allocate a lockdep entry. (assumes the graph_lock held, returns
* with NULL on failure)
*/
static struct lock_list *alloc_list_entry(void)
{
if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
- __raw_spin_unlock(&hash_lock);
- debug_locks_off();
+ if (!debug_locks_off_graph_unlock())
+ return NULL;
+
printk("BUG: MAX_LOCKDEP_ENTRIES too low!\n");
printk("turning off the locking correctness validator.\n");
return NULL;
@@ -140,21 +177,12 @@ void lockdep_on(void)
EXPORT_SYMBOL(lockdep_on);
-int lockdep_internal(void)
-{
- return current->lockdep_recursion != 0;
-}
-
-EXPORT_SYMBOL(lockdep_internal);
-
/*
* Debugging switches:
*/
#define VERBOSE 0
-#ifdef VERBOSE
-# define VERY_VERBOSE 0
-#endif
+#define VERY_VERBOSE 0
#if VERBOSE
# define HARDIRQ_VERBOSE 1
@@ -179,8 +207,8 @@ static int class_filter(struct lock_class *class)
!strcmp(class->name, "&struct->lockfield"))
return 1;
#endif
- /* Allow everything else. 0 would be filter everything else */
- return 1;
+ /* Filter everything else. 1 would be to allow everything else */
+ return 0;
}
#endif
@@ -214,7 +242,7 @@ static int softirq_verbose(struct lock_class *class)
/*
* Stack-trace: tightly packed array of stack backtrace
- * addresses. Protected by the hash_lock.
+ * addresses. Protected by the graph_lock.
*/
unsigned long nr_stack_trace_entries;
static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
@@ -228,25 +256,20 @@ static int save_trace(struct stack_trace *trace)
trace->skip = 3;
trace->all_contexts = 0;
- /* Make sure to not recurse in case the the unwinder needs to tak
-e locks. */
- lockdep_off();
save_stack_trace(trace, NULL);
- lockdep_on();
trace->max_entries = trace->nr_entries;
nr_stack_trace_entries += trace->nr_entries;
- if (DEBUG_LOCKS_WARN_ON(nr_stack_trace_entries > MAX_STACK_TRACE_ENTRIES))
- return 0;
if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) {
- __raw_spin_unlock(&hash_lock);
- if (debug_locks_off()) {
- printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
- printk("turning off the locking correctness validator.\n");
- dump_stack();
- }
+ if (!debug_locks_off_graph_unlock())
+ return 0;
+
+ printk("BUG: MAX_STACK_TRACE_ENTRIES too low!\n");
+ printk("turning off the locking correctness validator.\n");
+ dump_stack();
+
return 0;
}
@@ -357,7 +380,7 @@ get_usage_chars(struct lock_class *class, char *c1, char *c2, char *c3, char *c4
static void print_lock_name(struct lock_class *class)
{
- char str[128], c1, c2, c3, c4;
+ char str[KSYM_NAME_LEN + 1], c1, c2, c3, c4;
const char *name;
get_usage_chars(class, &c1, &c2, &c3, &c4);
@@ -379,7 +402,7 @@ static void print_lock_name(struct lock_class *class)
static void print_lockdep_cache(struct lockdep_map *lock)
{
const char *name;
- char str[128];
+ char str[KSYM_NAME_LEN + 1];
name = lock->name;
if (!name)
@@ -449,7 +472,9 @@ static void print_lock_dependencies(struct lock_class *class, int depth)
print_lock_class_header(class, depth);
list_for_each_entry(entry, &class->locks_after, entry) {
- DEBUG_LOCKS_WARN_ON(!entry->class);
+ if (DEBUG_LOCKS_WARN_ON(!entry->class))
+ return;
+
print_lock_dependencies(entry->class, depth + 1);
printk("%*s ... acquired at:\n",depth,"");
@@ -474,7 +499,8 @@ static int add_lock_to_list(struct lock_class *class, struct lock_class *this,
return 0;
entry->class = this;
- save_trace(&entry->trace);
+ if (!save_trace(&entry->trace))
+ return 0;
/*
* Since we never remove from the dependency list, the list can
@@ -532,9 +558,7 @@ print_circular_bug_header(struct lock_list *entry, unsigned int depth)
{
struct task_struct *curr = current;
- __raw_spin_unlock(&hash_lock);
- debug_locks_off();
- if (debug_locks_silent)
+ if (!debug_locks_off_graph_unlock() || debug_locks_silent)
return 0;
printk("\n=======================================================\n");
@@ -563,7 +587,9 @@ static noinline int print_circular_bug_tail(void)
return 0;
this.class = check_source->class;
- save_trace(&this.trace);
+ if (!save_trace(&this.trace))
+ return 0;
+
print_circular_bug_entry(&this, 0);
printk("\nother info that might help us debug this:\n\n");
@@ -579,8 +605,10 @@ static noinline int print_circular_bug_tail(void)
static int noinline print_infinite_recursion_bug(void)
{
- __raw_spin_unlock(&hash_lock);
- DEBUG_LOCKS_WARN_ON(1);
+ if (!debug_locks_off_graph_unlock())
+ return 0;
+
+ WARN_ON(1);
return 0;
}
@@ -715,9 +743,7 @@ print_bad_irq_dependency(struct task_struct *curr,
enum lock_usage_bit bit2,
const char *irqclass)
{
- __raw_spin_unlock(&hash_lock);
- debug_locks_off();
- if (debug_locks_silent)
+ if (!debug_locks_off_graph_unlock() || debug_locks_silent)
return 0;
printk("\n======================================================\n");
@@ -798,9 +824,7 @@ static int
print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
struct held_lock *next)
{
- debug_locks_off();
- __raw_spin_unlock(&hash_lock);
- if (debug_locks_silent)
+ if (!debug_locks_off_graph_unlock() || debug_locks_silent)
return 0;
printk("\n=============================================\n");
@@ -966,27 +990,24 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
&prev->class->locks_after, next->acquire_ip);
if (!ret)
return 0;
- /*
- * Return value of 2 signals 'dependency already added',
- * in that case we dont have to add the backlink either.
- */
- if (ret == 2)
- return 2;
+
ret = add_lock_to_list(next->class, prev->class,
&next->class->locks_before, next->acquire_ip);
+ if (!ret)
+ return 0;
/*
* Debugging printouts:
*/
if (verbose(prev->class) || verbose(next->class)) {
- __raw_spin_unlock(&hash_lock);
+ graph_unlock();
printk("\n new dependency: ");
print_lock_name(prev->class);
printk(" => ");
print_lock_name(next->class);
printk("\n");
dump_stack();
- __raw_spin_lock(&hash_lock);
+ return graph_lock();
}
return 1;
}
@@ -1025,7 +1046,8 @@ check_prevs_add(struct task_struct *curr, struct held_lock *next)
* added:
*/
if (hlock->read != 2) {
- check_prev_add(curr, hlock, next);
+ if (!check_prev_add(curr, hlock, next))
+ return 0;
/*
* Stop after the first non-trylock entry,
* as non-trylock entries have added their
@@ -1050,8 +1072,10 @@ check_prevs_add(struct task_struct *curr, struct held_lock *next)
}
return 1;
out_bug:
- __raw_spin_unlock(&hash_lock);
- DEBUG_LOCKS_WARN_ON(1);
+ if (!debug_locks_off_graph_unlock())
+ return 0;
+
+ WARN_ON(1);
return 0;
}
@@ -1182,6 +1206,7 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
struct lockdep_subclass_key *key;
struct list_head *hash_head;
struct lock_class *class;
+ unsigned long flags;
class = look_up_lock_class(lock, subclass);
if (likely(class))
@@ -1203,7 +1228,11 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
key = lock->key->subkeys + subclass;
hash_head = classhashentry(key);
- __raw_spin_lock(&hash_lock);
+ raw_local_irq_save(flags);
+ if (!graph_lock()) {
+ raw_local_irq_restore(flags);
+ return NULL;
+ }
/*
* We have to do the hash-walk again, to avoid races
* with another CPU:
@@ -1216,8 +1245,12 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
* the hash:
*/
if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
- __raw_spin_unlock(&hash_lock);
- debug_locks_off();
+ if (!debug_locks_off_graph_unlock()) {
+ raw_local_irq_restore(flags);
+ return NULL;
+ }
+ raw_local_irq_restore(flags);
+
printk("BUG: MAX_LOCKDEP_KEYS too low!\n");
printk("turning off the locking correctness validator.\n");
return NULL;
@@ -1238,16 +1271,24 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
list_add_tail_rcu(&class->hash_entry, hash_head);
if (verbose(class)) {
- __raw_spin_unlock(&hash_lock);
+ graph_unlock();
+ raw_local_irq_restore(flags);
+
printk("\nnew class %p: %s", class->key, class->name);
if (class->name_version > 1)
printk("#%d", class->name_version);
printk("\n");
dump_stack();
- __raw_spin_lock(&hash_lock);
+
+ raw_local_irq_save(flags);
+ if (!graph_lock()) {
+ raw_local_irq_restore(flags);
+ return NULL;
+ }
}
out_unlock_set:
- __raw_spin_unlock(&hash_lock);
+ graph_unlock();
+ raw_local_irq_restore(flags);
if (!subclass || force)
lock->class_cache = class;
@@ -1262,7 +1303,7 @@ out_unlock_set:
* add it and return 0 - in this case the new dependency chain is
* validated. If the key is already hashed, return 1.
*/
-static inline int lookup_chain_cache(u64 chain_key)
+static inline int lookup_chain_cache(u64 chain_key, struct lock_class *class)
{
struct list_head *hash_head = chainhashentry(chain_key);
struct lock_chain *chain;
@@ -1276,34 +1317,36 @@ static inline int lookup_chain_cache(u64 chain_key)
if (chain->chain_key == chain_key) {
cache_hit:
debug_atomic_inc(&chain_lookup_hits);
- /*
- * In the debugging case, force redundant checking
- * by returning 1:
- */
-#ifdef CONFIG_DEBUG_LOCKDEP
- __raw_spin_lock(&hash_lock);
- return 1;
-#endif
+ if (very_verbose(class))
+ printk("\nhash chain already cached, key: "
+ "%016Lx tail class: [%p] %s\n",
+ (unsigned long long)chain_key,
+ class->key, class->name);
return 0;
}
}
+ if (very_verbose(class))
+ printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
+ (unsigned long long)chain_key, class->key, class->name);
/*
* Allocate a new chain entry from the static array, and add
* it to the hash:
*/
- __raw_spin_lock(&hash_lock);
+ if (!graph_lock())
+ return 0;
/*
* We have to walk the chain again locked - to avoid duplicates:
*/
list_for_each_entry(chain, hash_head, entry) {
if (chain->chain_key == chain_key) {
- __raw_spin_unlock(&hash_lock);
+ graph_unlock();
goto cache_hit;
}
}
if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
- __raw_spin_unlock(&hash_lock);
- debug_locks_off();
+ if (!debug_locks_off_graph_unlock())
+ return 0;
+
printk("BUG: MAX_LOCKDEP_CHAINS too low!\n");
printk("turning off the locking correctness validator.\n");
return 0;
@@ -1379,9 +1422,7 @@ print_irq_inversion_bug(struct task_struct *curr, struct lock_class *other,
struct held_lock *this, int forwards,
const char *irqclass)
{
- __raw_spin_unlock(&hash_lock);
- debug_locks_off();
- if (debug_locks_silent)
+ if (!debug_locks_off_graph_unlock() || debug_locks_silent)
return 0;
printk("\n=========================================================\n");
@@ -1451,7 +1492,7 @@ check_usage_backwards(struct task_struct *curr, struct held_lock *this,
return print_irq_inversion_bug(curr, backwards_match, this, 0, irqclass);
}
-static inline void print_irqtrace_events(struct task_struct *curr)
+void print_irqtrace_events(struct task_struct *curr)
{
printk("irq event stamp: %u\n", curr->irq_events);
printk("hardirqs last enabled at (%u): ", curr->hardirq_enable_event);
@@ -1464,19 +1505,13 @@ static inline void print_irqtrace_events(struct task_struct *curr)
print_ip_sym(curr->softirq_disable_ip);
}
-#else
-static inline void print_irqtrace_events(struct task_struct *curr)
-{
-}
#endif
static int
print_usage_bug(struct task_struct *curr, struct held_lock *this,
enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
{
- __raw_spin_unlock(&hash_lock);
- debug_locks_off();
- if (debug_locks_silent)
+ if (!debug_locks_off_graph_unlock() || debug_locks_silent)
return 0;
printk("\n=================================\n");
@@ -1537,12 +1572,13 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this,
if (likely(this->class->usage_mask & new_mask))
return 1;
- __raw_spin_lock(&hash_lock);
+ if (!graph_lock())
+ return 0;
/*
* Make sure we didnt race:
*/
if (unlikely(this->class->usage_mask & new_mask)) {
- __raw_spin_unlock(&hash_lock);
+ graph_unlock();
return 1;
}
@@ -1728,15 +1764,16 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this,
debug_atomic_dec(&nr_unused_locks);
break;
default:
- debug_locks_off();
+ if (!debug_locks_off_graph_unlock())
+ return 0;
WARN_ON(1);
return 0;
}
- __raw_spin_unlock(&hash_lock);
+ graph_unlock();
/*
- * We must printk outside of the hash_lock:
+ * We must printk outside of the graph_lock:
*/
if (ret == 2) {
printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
@@ -2134,9 +2171,9 @@ out_calc_hash:
* We look up the chain_key and do the O(N^2) check and update of
* the dependencies only if this is a new dependency chain.
* (If lookup_chain_cache() returns with 1 it acquires
- * hash_lock for us)
+ * graph_lock for us)
*/
- if (!trylock && (check == 2) && lookup_chain_cache(chain_key)) {
+ if (!trylock && (check == 2) && lookup_chain_cache(chain_key, class)) {
/*
* Check whether last held lock:
*
@@ -2167,7 +2204,7 @@ out_calc_hash:
if (!chain_head && ret != 2)
if (!check_prevs_add(curr, hlock))
return 0;
- __raw_spin_unlock(&hash_lock);
+ graph_unlock();
}
curr->lockdep_depth++;
check_chain_key(curr);
@@ -2430,6 +2467,7 @@ EXPORT_SYMBOL_GPL(lock_release);
void lockdep_reset(void)
{
unsigned long flags;
+ int i;
raw_local_irq_save(flags);
current->curr_chain_key = 0;
@@ -2440,6 +2478,8 @@ void lockdep_reset(void)
nr_softirq_chains = 0;
nr_process_chains = 0;
debug_locks = 1;
+ for (i = 0; i < CHAINHASH_SIZE; i++)
+ INIT_LIST_HEAD(chainhash_table + i);
raw_local_irq_restore(flags);
}
@@ -2476,7 +2516,7 @@ void lockdep_free_key_range(void *start, unsigned long size)
int i;
raw_local_irq_save(flags);
- __raw_spin_lock(&hash_lock);
+ graph_lock();
/*
* Unhash all classes that were created by this module:
@@ -2490,7 +2530,7 @@ void lockdep_free_key_range(void *start, unsigned long size)
zap_class(class);
}
- __raw_spin_unlock(&hash_lock);
+ graph_unlock();
raw_local_irq_restore(flags);
}
@@ -2518,20 +2558,20 @@ void lockdep_reset_lock(struct lockdep_map *lock)
* Debug check: in the end all mapped classes should
* be gone.
*/
- __raw_spin_lock(&hash_lock);
+ graph_lock();
for (i = 0; i < CLASSHASH_SIZE; i++) {
head = classhash_table + i;
if (list_empty(head))
continue;
list_for_each_entry_safe(class, next, head, hash_entry) {
if (unlikely(class == lock->class_cache)) {
- __raw_spin_unlock(&hash_lock);
- DEBUG_LOCKS_WARN_ON(1);
+ if (debug_locks_off_graph_unlock())
+ WARN_ON(1);
goto out_restore;
}
}
}
- __raw_spin_unlock(&hash_lock);
+ graph_unlock();
out_restore:
raw_local_irq_restore(flags);
@@ -2645,6 +2685,7 @@ void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
}
local_irq_restore(flags);
}
+EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
static void print_held_locks_bug(struct task_struct *curr)
{
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-12-03 21:14:43 +0000