hid: jarvis: Supress kernel debug prints in atvr_raw_event()
[linux-3.10.git] / kernel / rcupdate.c
index a4e329d..48ab703 100644 (file)
@@ -19,7 +19,7 @@
  *
  * Authors: Dipankar Sarma <dipankar@in.ibm.com>
  *         Manfred Spraul <manfred@colorfullife.com>
- * 
+ *
  * Based on the original work by Paul McKenney <paulmck@us.ibm.com>
  * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
  * Papers:
@@ -27,7 +27,7 @@
  * http://lse.sourceforge.net/locking/rclock_OLS.2001.05.01c.sc.pdf (OLS2001)
  *
  * For detailed explanation of Read-Copy Update mechanism see -
- *             http://lse.sourceforge.net/locking/rcupdate.html
+ *             http://lse.sourceforge.net/locking/rcupdate.html
  *
  */
 #include <linux/types.h>
 #include <linux/smp.h>
 #include <linux/interrupt.h>
 #include <linux/sched.h>
-#include <asm/atomic.h>
+#include <linux/atomic.h>
 #include <linux/bitops.h>
 #include <linux/percpu.h>
 #include <linux/notifier.h>
 #include <linux/cpu.h>
 #include <linux/mutex.h>
+#include <linux/export.h>
+#include <linux/hardirq.h>
+#include <linux/delay.h>
 #include <linux/module.h>
 
-static DEFINE_PER_CPU(struct rcu_head, rcu_barrier_head) = {NULL};
-static atomic_t rcu_barrier_cpu_count;
-static DEFINE_MUTEX(rcu_barrier_mutex);
-static struct completion rcu_barrier_completion;
+#define CREATE_TRACE_POINTS
+#include <trace/events/rcu.h>
+
+#include "rcu.h"
+
+module_param(rcu_expedited, int, 0);
+
+#ifdef CONFIG_PREEMPT_RCU
+
+/*
+ * Preemptible RCU implementation for rcu_read_lock().
+ * Just increment ->rcu_read_lock_nesting, shared state will be updated
+ * if we block.
+ */
+void __rcu_read_lock(void)
+{
+       current->rcu_read_lock_nesting++;
+       barrier();  /* critical section after entry code. */
+}
+EXPORT_SYMBOL_GPL(__rcu_read_lock);
+
+/*
+ * Preemptible RCU implementation for rcu_read_unlock().
+ * Decrement ->rcu_read_lock_nesting.  If the result is zero (outermost
+ * rcu_read_unlock()) and ->rcu_read_unlock_special is non-zero, then
+ * invoke rcu_read_unlock_special() to clean up after a context switch
+ * in an RCU read-side critical section and other special cases.
+ */
+void __rcu_read_unlock(void)
+{
+       struct task_struct *t = current;
+
+       if (t->rcu_read_lock_nesting != 1) {
+               --t->rcu_read_lock_nesting;
+       } else {
+               barrier();  /* critical section before exit code. */
+               t->rcu_read_lock_nesting = INT_MIN;
+#ifdef CONFIG_PROVE_RCU_DELAY
+               udelay(10); /* Make preemption more probable. */
+#endif /* #ifdef CONFIG_PROVE_RCU_DELAY */
+               barrier();  /* assign before ->rcu_read_unlock_special load */
+               if (unlikely(ACCESS_ONCE(t->rcu_read_unlock_special)))
+                       rcu_read_unlock_special(t);
+               barrier();  /* ->rcu_read_unlock_special load before assign */
+               t->rcu_read_lock_nesting = 0;
+       }
+#ifdef CONFIG_PROVE_LOCKING
+       {
+               int rrln = ACCESS_ONCE(t->rcu_read_lock_nesting);
+
+               WARN_ON_ONCE(rrln < 0 && rrln > INT_MIN / 2);
+       }
+#endif /* #ifdef CONFIG_PROVE_LOCKING */
+}
+EXPORT_SYMBOL_GPL(__rcu_read_unlock);
+
+/*
+ * Check for a task exiting while in a preemptible-RCU read-side
+ * critical section, clean up if so.  No need to issue warnings,
+ * as debug_check_no_locks_held() already does this if lockdep
+ * is enabled.
+ */
+void exit_rcu(void)
+{
+       struct task_struct *t = current;
+
+       if (likely(list_empty(&current->rcu_node_entry)))
+               return;
+       t->rcu_read_lock_nesting = 1;
+       barrier();
+       t->rcu_read_unlock_special = RCU_READ_UNLOCK_BLOCKED;
+       __rcu_read_unlock();
+}
+
+#else /* #ifdef CONFIG_PREEMPT_RCU */
+
+void exit_rcu(void)
+{
+}
+
+#endif /* #else #ifdef CONFIG_PREEMPT_RCU */
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+static struct lock_class_key rcu_lock_key;
+struct lockdep_map rcu_lock_map =
+       STATIC_LOCKDEP_MAP_INIT("rcu_read_lock", &rcu_lock_key);
+EXPORT_SYMBOL_GPL(rcu_lock_map);
+
+static struct lock_class_key rcu_bh_lock_key;
+struct lockdep_map rcu_bh_lock_map =
+       STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_bh", &rcu_bh_lock_key);
+EXPORT_SYMBOL_GPL(rcu_bh_lock_map);
+
+static struct lock_class_key rcu_sched_lock_key;
+struct lockdep_map rcu_sched_lock_map =
+       STATIC_LOCKDEP_MAP_INIT("rcu_read_lock_sched", &rcu_sched_lock_key);
+EXPORT_SYMBOL_GPL(rcu_sched_lock_map);
+#endif
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+
+int debug_lockdep_rcu_enabled(void)
+{
+       return rcu_scheduler_active && debug_locks &&
+              current->lockdep_recursion == 0;
+}
+EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled);
+
+/**
+ * rcu_read_lock_bh_held() - might we be in RCU-bh read-side critical section?
+ *
+ * Check for bottom half being disabled, which covers both the
+ * CONFIG_PROVE_RCU and not cases.  Note that if someone uses
+ * rcu_read_lock_bh(), but then later enables BH, lockdep (if enabled)
+ * will show the situation.  This is useful for debug checks in functions
+ * that require that they be called within an RCU read-side critical
+ * section.
+ *
+ * Check debug_lockdep_rcu_enabled() to prevent false positives during boot.
+ *
+ * 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.
+ */
+int rcu_read_lock_bh_held(void)
+{
+       if (!debug_lockdep_rcu_enabled())
+               return 1;
+       if (rcu_is_cpu_idle())
+               return 0;
+       if (!rcu_lockdep_current_cpu_online())
+               return 0;
+       return in_softirq() || irqs_disabled();
+}
+EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held);
+
+#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
+
+struct rcu_synchronize {
+       struct rcu_head head;
+       struct completion completion;
+};
 
 /*
  * Awaken the corresponding synchronize_rcu() instance now that a
  * grace period has elapsed.
  */
-void wakeme_after_rcu(struct rcu_head  *head)
+static void wakeme_after_rcu(struct rcu_head  *head)
 {
        struct rcu_synchronize *rcu;
 
@@ -62,64 +202,267 @@ void wakeme_after_rcu(struct rcu_head  *head)
        complete(&rcu->completion);
 }
 
-/**
- * synchronize_rcu - wait until a grace period has elapsed.
- *
- * Control will return to the caller some time after a full grace
- * period has elapsed, in other words after all currently executing RCU
- * read-side critical sections have completed.  RCU read-side critical
- * sections are delimited by rcu_read_lock() and rcu_read_unlock(),
- * and may be nested.
+void wait_rcu_gp(call_rcu_func_t crf)
+{
+       struct rcu_synchronize rcu;
+
+       init_rcu_head_on_stack(&rcu.head);
+       init_completion(&rcu.completion);
+       /* Will wake me after RCU finished. */
+       crf(&rcu.head, wakeme_after_rcu);
+       /* Wait for it. */
+       wait_for_completion(&rcu.completion);
+       destroy_rcu_head_on_stack(&rcu.head);
+}
+EXPORT_SYMBOL_GPL(wait_rcu_gp);
+
+#ifdef CONFIG_PROVE_RCU
+/*
+ * wrapper function to avoid #include problems.
  */
-synchronize_rcu_xxx(synchronize_rcu, call_rcu)
-EXPORT_SYMBOL_GPL(synchronize_rcu);
+int rcu_my_thread_group_empty(void)
+{
+       return thread_group_empty(current);
+}
+EXPORT_SYMBOL_GPL(rcu_my_thread_group_empty);
+#endif /* #ifdef CONFIG_PROVE_RCU */
 
-static void rcu_barrier_callback(struct rcu_head *notused)
+#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
+static inline void debug_init_rcu_head(struct rcu_head *head)
 {
-       if (atomic_dec_and_test(&rcu_barrier_cpu_count))
-               complete(&rcu_barrier_completion);
+       debug_object_init(head, &rcuhead_debug_descr);
+}
+
+static inline void debug_rcu_head_free(struct rcu_head *head)
+{
+       debug_object_free(head, &rcuhead_debug_descr);
+}
+
+/*
+ * fixup_init is called when:
+ * - an active object is initialized
+ */
+static int rcuhead_fixup_init(void *addr, enum debug_obj_state state)
+{
+       struct rcu_head *head = addr;
+
+       switch (state) {
+       case ODEBUG_STATE_ACTIVE:
+               /*
+                * Ensure that queued callbacks are all executed.
+                * If we detect that we are nested in a RCU read-side critical
+                * section, we should simply fail, otherwise we would deadlock.
+                * In !PREEMPT configurations, there is no way to tell if we are
+                * in a RCU read-side critical section or not, so we never
+                * attempt any fixup and just print a warning.
+                */
+#ifndef CONFIG_PREEMPT
+               WARN_ON_ONCE(1);
+               return 0;
+#endif
+               if (rcu_preempt_depth() != 0 || preempt_count() != 0 ||
+                   irqs_disabled()) {
+                       WARN_ON_ONCE(1);
+                       return 0;
+               }
+               rcu_barrier();
+               rcu_barrier_sched();
+               rcu_barrier_bh();
+               debug_object_init(head, &rcuhead_debug_descr);
+               return 1;
+       default:
+               return 0;
+       }
+}
+
+/*
+ * fixup_activate is called when:
+ * - an active object is activated
+ * - an unknown object is activated (might be a statically initialized object)
+ * Activation is performed internally by call_rcu().
+ */
+static int rcuhead_fixup_activate(void *addr, enum debug_obj_state state)
+{
+       struct rcu_head *head = addr;
+
+       switch (state) {
+
+       case ODEBUG_STATE_NOTAVAILABLE:
+               /*
+                * This is not really a fixup. We just make sure that it is
+                * tracked in the object tracker.
+                */
+               debug_object_init(head, &rcuhead_debug_descr);
+               debug_object_activate(head, &rcuhead_debug_descr);
+               return 0;
+
+       case ODEBUG_STATE_ACTIVE:
+               /*
+                * Ensure that queued callbacks are all executed.
+                * If we detect that we are nested in a RCU read-side critical
+                * section, we should simply fail, otherwise we would deadlock.
+                * In !PREEMPT configurations, there is no way to tell if we are
+                * in a RCU read-side critical section or not, so we never
+                * attempt any fixup and just print a warning.
+                */
+#ifndef CONFIG_PREEMPT
+               WARN_ON_ONCE(1);
+               return 0;
+#endif
+               if (rcu_preempt_depth() != 0 || preempt_count() != 0 ||
+                   irqs_disabled()) {
+                       WARN_ON_ONCE(1);
+                       return 0;
+               }
+               rcu_barrier();
+               rcu_barrier_sched();
+               rcu_barrier_bh();
+               debug_object_activate(head, &rcuhead_debug_descr);
+               return 1;
+       default:
+               return 0;
+       }
 }
 
 /*
- * Called with preemption disabled, and from cross-cpu IRQ context.
+ * fixup_free is called when:
+ * - an active object is freed
  */
-static void rcu_barrier_func(void *notused)
+static int rcuhead_fixup_free(void *addr, enum debug_obj_state state)
 {
-       int cpu = smp_processor_id();
-       struct rcu_head *head = &per_cpu(rcu_barrier_head, cpu);
+       struct rcu_head *head = addr;
 
-       atomic_inc(&rcu_barrier_cpu_count);
-       call_rcu(head, rcu_barrier_callback);
+       switch (state) {
+       case ODEBUG_STATE_ACTIVE:
+               /*
+                * Ensure that queued callbacks are all executed.
+                * If we detect that we are nested in a RCU read-side critical
+                * section, we should simply fail, otherwise we would deadlock.
+                * In !PREEMPT configurations, there is no way to tell if we are
+                * in a RCU read-side critical section or not, so we never
+                * attempt any fixup and just print a warning.
+                */
+#ifndef CONFIG_PREEMPT
+               WARN_ON_ONCE(1);
+               return 0;
+#endif
+               if (rcu_preempt_depth() != 0 || preempt_count() != 0 ||
+                   irqs_disabled()) {
+                       WARN_ON_ONCE(1);
+                       return 0;
+               }
+               rcu_barrier();
+               rcu_barrier_sched();
+               rcu_barrier_bh();
+               debug_object_free(head, &rcuhead_debug_descr);
+               return 1;
+       default:
+               return 0;
+       }
 }
 
 /**
- * rcu_barrier - Wait until all the in-flight RCUs are complete.
+ * init_rcu_head_on_stack() - initialize on-stack rcu_head for debugobjects
+ * @head: pointer to rcu_head structure to be initialized
+ *
+ * This function informs debugobjects of a new rcu_head structure that
+ * has been allocated as an auto variable on the stack.  This function
+ * is not required for rcu_head structures that are statically defined or
+ * that are dynamically allocated on the heap.  This function has no
+ * effect for !CONFIG_DEBUG_OBJECTS_RCU_HEAD kernel builds.
+ */
+void init_rcu_head_on_stack(struct rcu_head *head)
+{
+       debug_object_init_on_stack(head, &rcuhead_debug_descr);
+}
+EXPORT_SYMBOL_GPL(init_rcu_head_on_stack);
+
+/**
+ * destroy_rcu_head_on_stack() - destroy on-stack rcu_head for debugobjects
+ * @head: pointer to rcu_head structure to be initialized
+ *
+ * This function informs debugobjects that an on-stack rcu_head structure
+ * is about to go out of scope.  As with init_rcu_head_on_stack(), this
+ * function is not required for rcu_head structures that are statically
+ * defined or that are dynamically allocated on the heap.  Also as with
+ * init_rcu_head_on_stack(), this function has no effect for
+ * !CONFIG_DEBUG_OBJECTS_RCU_HEAD kernel builds.
  */
-void rcu_barrier(void)
+void destroy_rcu_head_on_stack(struct rcu_head *head)
+{
+       debug_object_free(head, &rcuhead_debug_descr);
+}
+EXPORT_SYMBOL_GPL(destroy_rcu_head_on_stack);
+
+struct debug_obj_descr rcuhead_debug_descr = {
+       .name = "rcu_head",
+       .fixup_init = rcuhead_fixup_init,
+       .fixup_activate = rcuhead_fixup_activate,
+       .fixup_free = rcuhead_fixup_free,
+};
+EXPORT_SYMBOL_GPL(rcuhead_debug_descr);
+#endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
+
+#if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU) || defined(CONFIG_RCU_TRACE)
+void do_trace_rcu_torture_read(char *rcutorturename, struct rcu_head *rhp,
+                              unsigned long secs,
+                              unsigned long c_old, unsigned long c)
 {
-       BUG_ON(in_interrupt());
-       /* Take cpucontrol mutex to protect against CPU hotplug */
-       mutex_lock(&rcu_barrier_mutex);
-       init_completion(&rcu_barrier_completion);
-       atomic_set(&rcu_barrier_cpu_count, 0);
+       trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c);
+}
+EXPORT_SYMBOL_GPL(do_trace_rcu_torture_read);
+#else
+#define do_trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \
+       do { } while (0)
+#endif
+
+#ifdef CONFIG_RCU_STALL_COMMON
+
+#ifdef CONFIG_PROVE_RCU
+#define RCU_STALL_DELAY_DELTA         (5 * HZ)
+#else
+#define RCU_STALL_DELAY_DELTA         0
+#endif
+
+int rcu_cpu_stall_suppress __read_mostly; /* 1 = suppress stall warnings. */
+int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT;
+
+module_param(rcu_cpu_stall_suppress, int, 0644);
+module_param(rcu_cpu_stall_timeout, int, 0644);
+
+int rcu_jiffies_till_stall_check(void)
+{
+       int till_stall_check = ACCESS_ONCE(rcu_cpu_stall_timeout);
+
        /*
-        * The queueing of callbacks in all CPUs must be atomic with
-        * respect to RCU, otherwise one CPU may queue a callback,
-        * wait for a grace period, decrement barrier count and call
-        * complete(), while other CPUs have not yet queued anything.
-        * So, we need to make sure that grace periods cannot complete
-        * until all the callbacks are queued.
+        * Limit check must be consistent with the Kconfig limits
+        * for CONFIG_RCU_CPU_STALL_TIMEOUT.
         */
-       rcu_read_lock();
-       on_each_cpu(rcu_barrier_func, NULL, 0, 1);
-       rcu_read_unlock();
-       wait_for_completion(&rcu_barrier_completion);
-       mutex_unlock(&rcu_barrier_mutex);
+       if (till_stall_check < 3) {
+               ACCESS_ONCE(rcu_cpu_stall_timeout) = 3;
+               till_stall_check = 3;
+       } else if (till_stall_check > 300) {
+               ACCESS_ONCE(rcu_cpu_stall_timeout) = 300;
+               till_stall_check = 300;
+       }
+       return till_stall_check * HZ + RCU_STALL_DELAY_DELTA;
 }
-EXPORT_SYMBOL_GPL(rcu_barrier);
 
-void __init rcu_init(void)
+static int rcu_panic(struct notifier_block *this, unsigned long ev, void *ptr)
+{
+       rcu_cpu_stall_suppress = 1;
+       return NOTIFY_DONE;
+}
+
+static struct notifier_block rcu_panic_block = {
+       .notifier_call = rcu_panic,
+};
+
+static int __init check_cpu_stall_init(void)
 {
-       __rcu_init();
+       atomic_notifier_chain_register(&panic_notifier_list, &rcu_panic_block);
+       return 0;
 }
+early_initcall(check_cpu_stall_init);
 
+#endif /* #ifdef CONFIG_RCU_STALL_COMMON */