Merge branches 'doc.2014.04.29a', 'fixes.2014.04.29a' and 'torture.20…

…14.05.14a' into HEAD

doc.2014.04.29a:  Documentation updates.
fixes.2014.04.29a:  Miscellaneous fixes.
torture.2014.05.14a:  RCU/Lock torture tests.

include/linux/percpu.h

@@ -639,7 +639,7 @@ do {									\
 #  define raw_cpu_add_return_8(pcp, val)	raw_cpu_generic_add_return(pcp, val)
 # endif
 # define raw_cpu_add_return(pcp, val)	\
-	__pcpu_size_call_return2(raw_add_return_, pcp, val)
+	__pcpu_size_call_return2(raw_cpu_add_return_, pcp, val)
 #endif
 
 #define raw_cpu_sub_return(pcp, val)	raw_cpu_add_return(pcp, -(typeof(pcp))(val))

include/linux/rcupdate.h

@@ -44,14 +44,25 @@
 #include <linux/debugobjects.h>
 #include <linux/bug.h>
 #include <linux/compiler.h>
+#include <linux/percpu.h>
 #include <asm/barrier.h>
 
 extern int rcu_expedited; /* for sysctl */
 #ifdef CONFIG_RCU_TORTURE_TEST
 extern int rcutorture_runnable; /* for sysctl */
 #endif /* #ifdef CONFIG_RCU_TORTURE_TEST */
 
+enum rcutorture_type {
+	RCU_FLAVOR,
+	RCU_BH_FLAVOR,
+	RCU_SCHED_FLAVOR,
+	SRCU_FLAVOR,
+	INVALID_RCU_FLAVOR
+};
+
 #if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU)
+void rcutorture_get_gp_data(enum rcutorture_type test_type, int *flags,
+			    unsigned long *gpnum, unsigned long *completed);
 void rcutorture_record_test_transition(void);
 void rcutorture_record_progress(unsigned long vernum);
 void do_trace_rcu_torture_read(const char *rcutorturename,
@@ -60,6 +71,15 @@ void do_trace_rcu_torture_read(const char *rcutorturename,
 			       unsigned long c_old,
 			       unsigned long c);
 #else
+static inline void rcutorture_get_gp_data(enum rcutorture_type test_type,
+					  int *flags,
+					  unsigned long *gpnum,
+					  unsigned long *completed)
+{
+	*flags = 0;
+	*gpnum = 0;
+	*completed = 0;
+}
 static inline void rcutorture_record_test_transition(void)
 {
 }
@@ -267,6 +287,41 @@ static inline void rcu_user_hooks_switch(struct task_struct *prev,
 bool __rcu_is_watching(void);
 #endif /* #if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_RCU_TRACE) || defined(CONFIG_SMP) */
 
+/*
+ * Hooks for cond_resched() and friends to avoid RCU CPU stall warnings.
+ */
+
+#define RCU_COND_RESCHED_LIM 256	/* ms vs. 100s of ms. */
+DECLARE_PER_CPU(int, rcu_cond_resched_count);
+void rcu_resched(void);
+
+/*
+ * Is it time to report RCU quiescent states?
+ *
+ * Note unsynchronized access to rcu_cond_resched_count.  Yes, we might
+ * increment some random CPU's count, and possibly also load the result from
+ * yet another CPU's count.  We might even clobber some other CPU's attempt
+ * to zero its counter.  This is all OK because the goal is not precision,
+ * but rather reasonable amortization of rcu_note_context_switch() overhead
+ * and extremely high probability of avoiding RCU CPU stall warnings.
+ * Note that this function has to be preempted in just the wrong place,
+ * many thousands of times in a row, for anything bad to happen.
+ */
+static inline bool rcu_should_resched(void)
+{
+	return raw_cpu_inc_return(rcu_cond_resched_count) >=
+	       RCU_COND_RESCHED_LIM;
+}
+
+/*
+ * Report quiscent states to RCU if it is time to do so.
+ */
+static inline void rcu_cond_resched(void)
+{
+	if (unlikely(rcu_should_resched()))
+		rcu_resched();
+}
+
 /*
  * Infrastructure to implement the synchronize_() primitives in
  * TREE_RCU and rcu_barrier_() primitives in TINY_RCU.
@@ -328,7 +383,7 @@ extern struct lockdep_map rcu_lock_map;
 extern struct lockdep_map rcu_bh_lock_map;
 extern struct lockdep_map rcu_sched_lock_map;
 extern struct lockdep_map rcu_callback_map;
-extern int debug_lockdep_rcu_enabled(void);
+int debug_lockdep_rcu_enabled(void);
 
 /**
  * rcu_read_lock_held() - might we be in RCU read-side critical section?
@@ -949,6 +1004,9 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
  * pointers, but you must use rcu_assign_pointer() to initialize the
  * external-to-structure pointer -after- you have completely initialized
  * the reader-accessible portions of the linked structure.
+ *
+ * Note that unlike rcu_assign_pointer(), RCU_INIT_POINTER() provides no
+ * ordering guarantees for either the CPU or the compiler.
  */
 #define RCU_INIT_POINTER(p, v) \
 	do { \

include/linux/rcutiny.h

@@ -119,6 +119,10 @@ static inline void rcu_sched_force_quiescent_state(void)
 {
 }
 
+static inline void show_rcu_gp_kthreads(void)
+{
+}
+
 static inline void rcu_cpu_stall_reset(void)
 {
 }

include/linux/rcutree.h

@@ -84,6 +84,7 @@ extern unsigned long rcutorture_vernum;
 long rcu_batches_completed(void);
 long rcu_batches_completed_bh(void);
 long rcu_batches_completed_sched(void);
+void show_rcu_gp_kthreads(void);
 
 void rcu_force_quiescent_state(void);
 void rcu_bh_force_quiescent_state(void);

include/linux/torture.h

@@ -49,12 +49,6 @@
 #define VERBOSE_TOROUT_ERRSTRING(s) \
 	do { if (verbose) pr_alert("%s" TORTURE_FLAG "!!! %s\n", torture_type, s); } while (0)
 
-/* Definitions for a non-string torture-test module parameter. */
-#define torture_parm(type, name, init, msg) \
-	static type name = init; \
-	module_param(name, type, 0444); \
-	MODULE_PARM_DESC(name, msg);
-
 /* Definitions for online/offline exerciser. */
 int torture_onoff_init(long ooholdoff, long oointerval);
 char *torture_onoff_stats(char *page);
@@ -81,7 +75,7 @@ void stutter_wait(const char *title);
 int torture_stutter_init(int s);
 
 /* Initialization and cleanup. */
-void torture_init_begin(char *ttype, bool v, int *runnable);
+bool torture_init_begin(char *ttype, bool v, int *runnable);
 void torture_init_end(void);
 bool torture_cleanup(void);
 bool torture_must_stop(void);

kernel/locking/locktorture.c

@@ -82,14 +82,14 @@ struct lock_writer_stress_stats {
 };
 static struct lock_writer_stress_stats *lwsa;
 
-#if defined(MODULE) || defined(CONFIG_LOCK_TORTURE_TEST_RUNNABLE)
+#if defined(MODULE)
 #define LOCKTORTURE_RUNNABLE_INIT 1
 #else
 #define LOCKTORTURE_RUNNABLE_INIT 0
 #endif
 int locktorture_runnable = LOCKTORTURE_RUNNABLE_INIT;
 module_param(locktorture_runnable, int, 0444);
-MODULE_PARM_DESC(locktorture_runnable, "Start locktorture at boot");
+MODULE_PARM_DESC(locktorture_runnable, "Start locktorture at module init");
 
 /* Forward reference. */
 static void lock_torture_cleanup(void);
@@ -219,7 +219,8 @@ static int lock_torture_writer(void *arg)
 	set_user_nice(current, 19);
 
 	do {
-		schedule_timeout_uninterruptible(1);
+		if ((torture_random(&rand) & 0xfffff) == 0)
+			schedule_timeout_uninterruptible(1);
 		cur_ops->writelock();
 		if (WARN_ON_ONCE(lock_is_write_held))
 			lwsp->n_write_lock_fail++;
@@ -354,7 +355,8 @@ static int __init lock_torture_init(void)
 		&lock_busted_ops, &spin_lock_ops, &spin_lock_irq_ops,
 	};
 
-	torture_init_begin(torture_type, verbose, &locktorture_runnable);
+	if (!torture_init_begin(torture_type, verbose, &locktorture_runnable))
+		return -EBUSY;
 
 	/* Process args and tell the world that the torturer is on the job. */
 	for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {