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Diffstat (limited to 'kernel')
-rw-r--r--kernel/locking/lockdep.c111
-rw-r--r--kernel/locking/rtmutex.c68
-rw-r--r--kernel/locking/rtmutex_common.h5
3 files changed, 126 insertions, 58 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 589d763a49b3..4d7ffc0a0d00 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -506,13 +506,13 @@ static void __print_lock_name(struct lock_class *class)
name = class->name;
if (!name) {
name = __get_key_name(class->key, str);
- printk("%s", name);
+ printk(KERN_CONT "%s", name);
} else {
- printk("%s", name);
+ printk(KERN_CONT "%s", name);
if (class->name_version > 1)
- printk("#%d", class->name_version);
+ printk(KERN_CONT "#%d", class->name_version);
if (class->subclass)
- printk("/%d", class->subclass);
+ printk(KERN_CONT "/%d", class->subclass);
}
}
@@ -522,9 +522,9 @@ static void print_lock_name(struct lock_class *class)
get_usage_chars(class, usage);
- printk(" (");
+ printk(KERN_CONT " (");
__print_lock_name(class);
- printk("){%s}", usage);
+ printk(KERN_CONT "){%s}", usage);
}
static void print_lockdep_cache(struct lockdep_map *lock)
@@ -536,7 +536,7 @@ static void print_lockdep_cache(struct lockdep_map *lock)
if (!name)
name = __get_key_name(lock->key->subkeys, str);
- printk("%s", name);
+ printk(KERN_CONT "%s", name);
}
static void print_lock(struct held_lock *hlock)
@@ -551,13 +551,13 @@ static void print_lock(struct held_lock *hlock)
barrier();
if (!class_idx || (class_idx - 1) >= MAX_LOCKDEP_KEYS) {
- printk("<RELEASED>\n");
+ printk(KERN_CONT "<RELEASED>\n");
return;
}
print_lock_name(lock_classes + class_idx - 1);
- printk(", at: ");
- print_ip_sym(hlock->acquire_ip);
+ printk(KERN_CONT ", at: [<%p>] %pS\n",
+ (void *)hlock->acquire_ip, (void *)hlock->acquire_ip);
}
static void lockdep_print_held_locks(struct task_struct *curr)
@@ -792,8 +792,8 @@ register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
printk("\nnew class %p: %s", class->key, class->name);
if (class->name_version > 1)
- printk("#%d", class->name_version);
- printk("\n");
+ printk(KERN_CONT "#%d", class->name_version);
+ printk(KERN_CONT "\n");
dump_stack();
if (!graph_lock()) {
@@ -1071,7 +1071,7 @@ print_circular_bug_entry(struct lock_list *target, int depth)
return 0;
printk("\n-> #%u", depth);
print_lock_name(target->class);
- printk(":\n");
+ printk(KERN_CONT ":\n");
print_stack_trace(&target->trace, 6);
return 0;
@@ -1102,11 +1102,11 @@ print_circular_lock_scenario(struct held_lock *src,
if (parent != source) {
printk("Chain exists of:\n ");
__print_lock_name(source);
- printk(" --> ");
+ printk(KERN_CONT " --> ");
__print_lock_name(parent);
- printk(" --> ");
+ printk(KERN_CONT " --> ");
__print_lock_name(target);
- printk("\n\n");
+ printk(KERN_CONT "\n\n");
}
printk(" Possible unsafe locking scenario:\n\n");
@@ -1114,16 +1114,16 @@ print_circular_lock_scenario(struct held_lock *src,
printk(" ---- ----\n");
printk(" lock(");
__print_lock_name(target);
- printk(");\n");
+ printk(KERN_CONT ");\n");
printk(" lock(");
__print_lock_name(parent);
- printk(");\n");
+ printk(KERN_CONT ");\n");
printk(" lock(");
__print_lock_name(target);
- printk(");\n");
+ printk(KERN_CONT ");\n");
printk(" lock(");
__print_lock_name(source);
- printk(");\n");
+ printk(KERN_CONT ");\n");
printk("\n *** DEADLOCK ***\n\n");
}
@@ -1359,22 +1359,22 @@ static void print_lock_class_header(struct lock_class *class, int depth)
printk("%*s->", depth, "");
print_lock_name(class);
- printk(" ops: %lu", class->ops);
- printk(" {\n");
+ printk(KERN_CONT " ops: %lu", class->ops);
+ printk(KERN_CONT " {\n");
for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
if (class->usage_mask & (1 << bit)) {
int len = depth;
len += printk("%*s %s", depth, "", usage_str[bit]);
- len += printk(" at:\n");
+ len += printk(KERN_CONT " at:\n");
print_stack_trace(class->usage_traces + bit, len);
}
}
printk("%*s }\n", depth, "");
- printk("%*s ... key at: ",depth,"");
- print_ip_sym((unsigned long)class->key);
+ printk("%*s ... key at: [<%p>] %pS\n",
+ depth, "", class->key, class->key);
}
/*
@@ -1437,11 +1437,11 @@ print_irq_lock_scenario(struct lock_list *safe_entry,
if (middle_class != unsafe_class) {
printk("Chain exists of:\n ");
__print_lock_name(safe_class);
- printk(" --> ");
+ printk(KERN_CONT " --> ");
__print_lock_name(middle_class);
- printk(" --> ");
+ printk(KERN_CONT " --> ");
__print_lock_name(unsafe_class);
- printk("\n\n");
+ printk(KERN_CONT "\n\n");
}
printk(" Possible interrupt unsafe locking scenario:\n\n");
@@ -1449,18 +1449,18 @@ print_irq_lock_scenario(struct lock_list *safe_entry,
printk(" ---- ----\n");
printk(" lock(");
__print_lock_name(unsafe_class);
- printk(");\n");
+ printk(KERN_CONT ");\n");
printk(" local_irq_disable();\n");
printk(" lock(");
__print_lock_name(safe_class);
- printk(");\n");
+ printk(KERN_CONT ");\n");
printk(" lock(");
__print_lock_name(middle_class);
- printk(");\n");
+ printk(KERN_CONT ");\n");
printk(" <Interrupt>\n");
printk(" lock(");
__print_lock_name(safe_class);
- printk(");\n");
+ printk(KERN_CONT ");\n");
printk("\n *** DEADLOCK ***\n\n");
}
@@ -1497,9 +1497,9 @@ print_bad_irq_dependency(struct task_struct *curr,
print_lock(prev);
printk("which would create a new lock dependency:\n");
print_lock_name(hlock_class(prev));
- printk(" ->");
+ printk(KERN_CONT " ->");
print_lock_name(hlock_class(next));
- printk("\n");
+ printk(KERN_CONT "\n");
printk("\nbut this new dependency connects a %s-irq-safe lock:\n",
irqclass);
@@ -1521,8 +1521,7 @@ print_bad_irq_dependency(struct task_struct *curr,
lockdep_print_held_locks(curr);
- printk("\nthe dependencies between %s-irq-safe lock", irqclass);
- printk(" and the holding lock:\n");
+ printk("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass);
if (!save_trace(&prev_root->trace))
return 0;
print_shortest_lock_dependencies(backwards_entry, prev_root);
@@ -1694,10 +1693,10 @@ print_deadlock_scenario(struct held_lock *nxt,
printk(" ----\n");
printk(" lock(");
__print_lock_name(prev);
- printk(");\n");
+ printk(KERN_CONT ");\n");
printk(" lock(");
__print_lock_name(next);
- printk(");\n");
+ printk(KERN_CONT ");\n");
printk("\n *** DEADLOCK ***\n\n");
printk(" May be due to missing lock nesting notation\n\n");
}
@@ -1891,9 +1890,9 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
graph_unlock();
printk("\n new dependency: ");
print_lock_name(hlock_class(prev));
- printk(" => ");
+ printk(KERN_CONT " => ");
print_lock_name(hlock_class(next));
- printk("\n");
+ printk(KERN_CONT "\n");
dump_stack();
return graph_lock();
}
@@ -2343,11 +2342,11 @@ print_usage_bug_scenario(struct held_lock *lock)
printk(" ----\n");
printk(" lock(");
__print_lock_name(class);
- printk(");\n");
+ printk(KERN_CONT ");\n");
printk(" <Interrupt>\n");
printk(" lock(");
__print_lock_name(class);
- printk(");\n");
+ printk(KERN_CONT ");\n");
printk("\n *** DEADLOCK ***\n\n");
}
@@ -2522,14 +2521,18 @@ check_usage_backwards(struct task_struct *curr, struct held_lock *this,
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);
- print_ip_sym(curr->hardirq_enable_ip);
- printk("hardirqs last disabled at (%u): ", curr->hardirq_disable_event);
- print_ip_sym(curr->hardirq_disable_ip);
- printk("softirqs last enabled at (%u): ", curr->softirq_enable_event);
- print_ip_sym(curr->softirq_enable_ip);
- printk("softirqs last disabled at (%u): ", curr->softirq_disable_event);
- print_ip_sym(curr->softirq_disable_ip);
+ printk("hardirqs last enabled at (%u): [<%p>] %pS\n",
+ curr->hardirq_enable_event, (void *)curr->hardirq_enable_ip,
+ (void *)curr->hardirq_enable_ip);
+ printk("hardirqs last disabled at (%u): [<%p>] %pS\n",
+ curr->hardirq_disable_event, (void *)curr->hardirq_disable_ip,
+ (void *)curr->hardirq_disable_ip);
+ printk("softirqs last enabled at (%u): [<%p>] %pS\n",
+ curr->softirq_enable_event, (void *)curr->softirq_enable_ip,
+ (void *)curr->softirq_enable_ip);
+ printk("softirqs last disabled at (%u): [<%p>] %pS\n",
+ curr->softirq_disable_event, (void *)curr->softirq_disable_ip,
+ (void *)curr->softirq_disable_ip);
}
static int HARDIRQ_verbose(struct lock_class *class)
@@ -3235,8 +3238,8 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
if (very_verbose(class)) {
printk("\nacquire class [%p] %s", class->key, class->name);
if (class->name_version > 1)
- printk("#%d", class->name_version);
- printk("\n");
+ printk(KERN_CONT "#%d", class->name_version);
+ printk(KERN_CONT "\n");
dump_stack();
}
@@ -3378,7 +3381,7 @@ print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
printk("%s/%d is trying to release lock (",
curr->comm, task_pid_nr(curr));
print_lockdep_cache(lock);
- printk(") at:\n");
+ printk(KERN_CONT ") at:\n");
print_ip_sym(ip);
printk("but there are no more locks to release!\n");
printk("\nother info that might help us debug this:\n");
@@ -3871,7 +3874,7 @@ print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
printk("%s/%d is trying to contend lock (",
curr->comm, task_pid_nr(curr));
print_lockdep_cache(lock);
- printk(") at:\n");
+ printk(KERN_CONT ") at:\n");
print_ip_sym(ip);
printk("but there are no locks held!\n");
printk("\nother info that might help us debug this:\n");
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 1ec0f48962b3..2c49d76f96c3 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -65,8 +65,72 @@ static inline void clear_rt_mutex_waiters(struct rt_mutex *lock)
static void fixup_rt_mutex_waiters(struct rt_mutex *lock)
{
- if (!rt_mutex_has_waiters(lock))
- clear_rt_mutex_waiters(lock);
+ unsigned long owner, *p = (unsigned long *) &lock->owner;
+
+ if (rt_mutex_has_waiters(lock))
+ return;
+
+ /*
+ * The rbtree has no waiters enqueued, now make sure that the
+ * lock->owner still has the waiters bit set, otherwise the
+ * following can happen:
+ *
+ * CPU 0 CPU 1 CPU2
+ * l->owner=T1
+ * rt_mutex_lock(l)
+ * lock(l->lock)
+ * l->owner = T1 | HAS_WAITERS;
+ * enqueue(T2)
+ * boost()
+ * unlock(l->lock)
+ * block()
+ *
+ * rt_mutex_lock(l)
+ * lock(l->lock)
+ * l->owner = T1 | HAS_WAITERS;
+ * enqueue(T3)
+ * boost()
+ * unlock(l->lock)
+ * block()
+ * signal(->T2) signal(->T3)
+ * lock(l->lock)
+ * dequeue(T2)
+ * deboost()
+ * unlock(l->lock)
+ * lock(l->lock)
+ * dequeue(T3)
+ * ==> wait list is empty
+ * deboost()
+ * unlock(l->lock)
+ * lock(l->lock)
+ * fixup_rt_mutex_waiters()
+ * if (wait_list_empty(l) {
+ * l->owner = owner
+ * owner = l->owner & ~HAS_WAITERS;
+ * ==> l->owner = T1
+ * }
+ * lock(l->lock)
+ * rt_mutex_unlock(l) fixup_rt_mutex_waiters()
+ * if (wait_list_empty(l) {
+ * owner = l->owner & ~HAS_WAITERS;
+ * cmpxchg(l->owner, T1, NULL)
+ * ===> Success (l->owner = NULL)
+ *
+ * l->owner = owner
+ * ==> l->owner = T1
+ * }
+ *
+ * With the check for the waiter bit in place T3 on CPU2 will not
+ * overwrite. All tasks fiddling with the waiters bit are
+ * serialized by l->lock, so nothing else can modify the waiters
+ * bit. If the bit is set then nothing can change l->owner either
+ * so the simple RMW is safe. The cmpxchg() will simply fail if it
+ * happens in the middle of the RMW because the waiters bit is
+ * still set.
+ */
+ owner = READ_ONCE(*p);
+ if (owner & RT_MUTEX_HAS_WAITERS)
+ WRITE_ONCE(*p, owner & ~RT_MUTEX_HAS_WAITERS);
}
/*
diff --git a/kernel/locking/rtmutex_common.h b/kernel/locking/rtmutex_common.h
index 4f5f83c7d2d3..e317e1cbb3eb 100644
--- a/kernel/locking/rtmutex_common.h
+++ b/kernel/locking/rtmutex_common.h
@@ -75,8 +75,9 @@ task_top_pi_waiter(struct task_struct *p)
static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
{
- return (struct task_struct *)
- ((unsigned long)lock->owner & ~RT_MUTEX_OWNER_MASKALL);
+ unsigned long owner = (unsigned long) READ_ONCE(lock->owner);
+
+ return (struct task_struct *) (owner & ~RT_MUTEX_OWNER_MASKALL);
}
/*
generated by cgit v1.2.3 (git 2.0.4) at 2024-11-13 20:58:59 +0000