extern void rcu_irq_enter(void);
extern void rcu_irq_exit(void);
+/**
+ * RCU_NONIDLE - Indicate idle-loop code that needs RCU readers
+ * @a: Code that RCU needs to pay attention to.
+ *
+ * RCU, RCU-bh, and RCU-sched read-side critical sections are forbidden
+ * in the inner idle loop, that is, between the rcu_idle_enter() and
+ * the rcu_idle_exit() -- RCU will happily ignore any such read-side
+ * critical sections. However, things like powertop need tracepoints
+ * in the inner idle loop.
+ *
+ * This macro provides the way out: RCU_NONIDLE(do_something_with_RCU())
+ * will tell RCU that it needs to pay attending, invoke its argument
+ * (in this example, a call to the do_something_with_RCU() function),
+ * and then tell RCU to go back to ignoring this CPU. It is permissible
+ * to nest RCU_NONIDLE() wrappers, but the nesting level is currently
+ * quite limited. If deeper nesting is required, it will be necessary
+ * to adjust DYNTICK_TASK_NESTING_VALUE accordingly.
+ *
+ * This macro may be used from process-level code only.
+ */
+#define RCU_NONIDLE(a) \
+ do { \
+ rcu_idle_exit(); \
+ do { a; } while (0); \
+ rcu_idle_enter(); \
+ } while (0)
+
/*
* Infrastructure to implement the synchronize_() primitives in
* TREE_RCU and rcu_barrier_() primitives in TINY_RCU.
}
#endif /* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
+#if defined(CONFIG_HOTPLUG_CPU) && defined(CONFIG_PROVE_RCU)
+bool rcu_lockdep_current_cpu_online(void);
+#else /* #if defined(CONFIG_HOTPLUG_CPU) && defined(CONFIG_PROVE_RCU) */
+static inline bool rcu_lockdep_current_cpu_online(void)
+{
+ return 1;
+}
+#endif /* #else #if defined(CONFIG_HOTPLUG_CPU) && defined(CONFIG_PROVE_RCU) */
+
#ifdef CONFIG_DEBUG_LOCK_ALLOC
#ifdef CONFIG_PROVE_RCU
static inline void rcu_lock_acquire(struct lockdep_map *map)
{
- WARN_ON_ONCE(rcu_is_cpu_idle());
lock_acquire(map, 0, 0, 2, 1, NULL, _THIS_IP_);
}
static inline void rcu_lock_release(struct lockdep_map *map)
{
- WARN_ON_ONCE(rcu_is_cpu_idle());
lock_release(map, 1, _THIS_IP_);
}
* occur in the same context, for example, it is illegal to invoke
* rcu_read_unlock() in process context if the matching rcu_read_lock()
* was invoked from within an irq handler.
+ *
+ * Note that rcu_read_lock() is disallowed if the CPU is either idle or
+ * offline from an RCU perspective, so check for those as well.
*/
static inline int rcu_read_lock_held(void)
{
return 1;
if (rcu_is_cpu_idle())
return 0;
+ if (!rcu_lockdep_current_cpu_online())
+ return 0;
return lock_is_held(&rcu_lock_map);
}
* notice an extended quiescent state to other CPUs that started a grace
* period. Otherwise we would delay any grace period as long as we run in
* the idle task.
+ *
+ * Similarly, we avoid claiming an SRCU read lock held if the current
+ * CPU is offline.
*/
#ifdef CONFIG_PREEMPT_COUNT
static inline int rcu_read_lock_sched_held(void)
return 1;
if (rcu_is_cpu_idle())
return 0;
+ if (!rcu_lockdep_current_cpu_online())
+ return 0;
if (debug_locks)
lockdep_opinion = lock_is_held(&rcu_sched_lock_map);
return lockdep_opinion || preempt_count() != 0 || irqs_disabled();
*/
#define rcu_lockdep_assert(c, s) \
do { \
- static bool __warned; \
+ static bool __section(.data.unlikely) __warned; \
if (debug_lockdep_rcu_enabled() && !__warned && !(c)) { \
__warned = true; \
lockdep_rcu_suspicious(__FILE__, __LINE__, s); \
} \
} while (0)
+#if defined(CONFIG_PROVE_RCU) && !defined(CONFIG_PREEMPT_RCU)
+static inline void rcu_preempt_sleep_check(void)
+{
+ rcu_lockdep_assert(!lock_is_held(&rcu_lock_map),
+ "Illegal context switch in RCU read-side "
+ "critical section");
+}
+#else /* #ifdef CONFIG_PROVE_RCU */
+static inline void rcu_preempt_sleep_check(void)
+{
+}
+#endif /* #else #ifdef CONFIG_PROVE_RCU */
+
#define rcu_sleep_check() \
do { \
+ rcu_preempt_sleep_check(); \
rcu_lockdep_assert(!lock_is_held(&rcu_bh_lock_map), \
"Illegal context switch in RCU-bh" \
" read-side critical section"); \
* NULL. Although rcu_access_pointer() may also be used in cases where
* update-side locks prevent the value of the pointer from changing, you
* should instead use rcu_dereference_protected() for this use case.
+ *
+ * It is also permissible to use rcu_access_pointer() when read-side
+ * access to the pointer was removed at least one grace period ago, as
+ * is the case in the context of the RCU callback that is freeing up
+ * the data, or after a synchronize_rcu() returns. This can be useful
+ * when tearing down multi-linked structures after a grace period
+ * has elapsed.
*/
#define rcu_access_pointer(p) __rcu_access_pointer((p), __rcu)
__rcu_read_lock();
__acquire(RCU);
rcu_lock_acquire(&rcu_lock_map);
+ rcu_lockdep_assert(!rcu_is_cpu_idle(),
+ "rcu_read_lock() used illegally while idle");
}
/*
*/
static inline void rcu_read_unlock(void)
{
+ rcu_lockdep_assert(!rcu_is_cpu_idle(),
+ "rcu_read_unlock() used illegally while idle");
rcu_lock_release(&rcu_lock_map);
__release(RCU);
__rcu_read_unlock();
local_bh_disable();
__acquire(RCU_BH);
rcu_lock_acquire(&rcu_bh_lock_map);
+ rcu_lockdep_assert(!rcu_is_cpu_idle(),
+ "rcu_read_lock_bh() used illegally while idle");
}
/*
*/
static inline void rcu_read_unlock_bh(void)
{
+ rcu_lockdep_assert(!rcu_is_cpu_idle(),
+ "rcu_read_unlock_bh() used illegally while idle");
rcu_lock_release(&rcu_bh_lock_map);
__release(RCU_BH);
local_bh_enable();
preempt_disable();
__acquire(RCU_SCHED);
rcu_lock_acquire(&rcu_sched_lock_map);
+ rcu_lockdep_assert(!rcu_is_cpu_idle(),
+ "rcu_read_lock_sched() used illegally while idle");
}
/* Used by lockdep and tracing: cannot be traced, cannot call lockdep. */
*/
static inline void rcu_read_unlock_sched(void)
{
+ rcu_lockdep_assert(!rcu_is_cpu_idle(),
+ "rcu_read_unlock_sched() used illegally while idle");
rcu_lock_release(&rcu_sched_lock_map);
__release(RCU_SCHED);
preempt_enable();
/* See the kfree_rcu() header comment. */
BUILD_BUG_ON(!__is_kfree_rcu_offset(offset));
- call_rcu(head, (rcu_callback)offset);
+ kfree_call_rcu(head, (rcu_callback)offset);
}
/**
projects / linux-beck.git / blobdiff