Merge branch 'rcu/next' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu

Pull RCU updates from Paul E. McKenney:

	* Update RCU documentation.  These were posted to LKML at
	  https://lkml.org/lkml/2014/2/17/555.

	* Miscellaneous fixes.  These were posted to LKML at
	  https://lkml.org/lkml/2014/2/17/530.  Note that two of these
	  are RCU changes to other maintainer's trees: add1f0995454
	  (fs) and 8857563b819b (notifer), both of which substitute
	  rcu_access_pointer() for rcu_dereference_raw().

	* Real-time latency fixes.  These were posted to LKML at
	  https://lkml.org/lkml/2014/2/17/544.

	* Torture-test changes, including refactoring of rcutorture
	  and introduction of a vestigial locktorture.  These were posted
	  to LKML at https://lkml.org/lkml/2014/2/17/599.

Signed-off-by: Ingo Molnar <mingo@kernel.org>

6 files changed, 165 insertions, 66 deletions

diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index dbaf99084112..8183b46fbaa2 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -247,9 +247,10 @@ static inline void list_splice_init_rcu(struct list_head *list,
  * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock().
  */
 #define list_entry_rcu(ptr, type, member) \
-        ({typeof (*ptr) __rcu *__ptr = (typeof (*ptr) __rcu __force *)ptr; \
-         container_of((typeof(ptr))rcu_dereference_raw(__ptr), type, member); \
-        })
+({ \
+        typeof(*ptr) __rcu *__ptr = (typeof(*ptr) __rcu __force *)ptr; \
+        container_of((typeof(ptr))rcu_dereference_raw(__ptr), type, member); \
+})
 
 /**
  * Where are list_empty_rcu() and list_first_entry_rcu()?
@@ -285,11 +286,11 @@ static inline void list_splice_init_rcu(struct list_head *list,
  * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock().
  */
 #define list_first_or_null_rcu(ptr, type, member) \
-        ({struct list_head *__ptr = (ptr); \
-          struct list_head *__next = ACCESS_ONCE(__ptr->next); \
-          likely(__ptr != __next) ? \
-                list_entry_rcu(__next, type, member) : NULL; \
-        })
+({ \
+        struct list_head *__ptr = (ptr); \
+        struct list_head *__next = ACCESS_ONCE(__ptr->next); \
+        likely(__ptr != __next) ? list_entry_rcu(__next, type, member) : NULL; \
+})
 
 /**
  * list_for_each_entry_rcu      -       iterate over rcu list of given type
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 72bf3a01a4ee..cda2583d67e9 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -12,8 +12,8 @@
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ * along with this program; if not, you can access it online at
+ * http://www.gnu.org/licenses/gpl-2.0.html.
  *
  * Copyright IBM Corporation, 2001
  *
@@ -44,7 +44,9 @@
 #include <linux/debugobjects.h>
 #include <linux/bug.h>
 #include <linux/compiler.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 */
@@ -479,11 +481,9 @@ static inline void rcu_preempt_sleep_check(void)
         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");      \
+                                   "Illegal context switch in RCU-bh read-side critical section"); \
                 rcu_lockdep_assert(!lock_is_held(&rcu_sched_lock_map),  \
-                                   "Illegal context switch in RCU-sched"\
-                                   " read-side critical section");      \
+                                   "Illegal context switch in RCU-sched read-side critical section"); \
         } while (0)
 
 #else /* #ifdef CONFIG_PROVE_RCU */
@@ -510,43 +510,40 @@ static inline void rcu_preempt_sleep_check(void)
 #endif /* #else #ifdef __CHECKER__ */
 
 #define __rcu_access_pointer(p, space) \
-        ({ \
-                typeof(*p) *_________p1 = (typeof(*p)*__force )ACCESS_ONCE(p); \
-                rcu_dereference_sparse(p, space); \
-                ((typeof(*p) __force __kernel *)(_________p1)); \
-        })
+({ \
+        typeof(*p) *_________p1 = (typeof(*p) *__force)ACCESS_ONCE(p); \
+        rcu_dereference_sparse(p, space); \
+        ((typeof(*p) __force __kernel *)(_________p1)); \
+})
 #define __rcu_dereference_check(p, c, space) \
-        ({ \
-                typeof(*p) *_________p1 = (typeof(*p)*__force )ACCESS_ONCE(p); \
-                rcu_lockdep_assert(c, "suspicious rcu_dereference_check()" \
-                                      " usage"); \
-                rcu_dereference_sparse(p, space); \
-                smp_read_barrier_depends(); \
-                ((typeof(*p) __force __kernel *)(_________p1)); \
-        })
+({ \
+        typeof(*p) *_________p1 = (typeof(*p) *__force)ACCESS_ONCE(p); \
+        rcu_lockdep_assert(c, "suspicious rcu_dereference_check() usage"); \
+        rcu_dereference_sparse(p, space); \
+        smp_read_barrier_depends(); /* Dependency order vs. p above. */ \
+        ((typeof(*p) __force __kernel *)(_________p1)); \
+})
 #define __rcu_dereference_protected(p, c, space) \
-        ({ \
-                rcu_lockdep_assert(c, "suspicious rcu_dereference_protected()" \
-                                      " usage"); \
-                rcu_dereference_sparse(p, space); \
-                ((typeof(*p) __force __kernel *)(p)); \
-        })
+({ \
+        rcu_lockdep_assert(c, "suspicious rcu_dereference_protected() usage"); \
+        rcu_dereference_sparse(p, space); \
+        ((typeof(*p) __force __kernel *)(p)); \
+})
 
 #define __rcu_access_index(p, space) \
-        ({ \
-                typeof(p) _________p1 = ACCESS_ONCE(p); \
-                rcu_dereference_sparse(p, space); \
-                (_________p1); \
-        })
+({ \
+        typeof(p) _________p1 = ACCESS_ONCE(p); \
+        rcu_dereference_sparse(p, space); \
+        (_________p1); \
+})
 #define __rcu_dereference_index_check(p, c) \
-        ({ \
-                typeof(p) _________p1 = ACCESS_ONCE(p); \
-                rcu_lockdep_assert(c, \
-                                   "suspicious rcu_dereference_index_check()" \
-                                   " usage"); \
-                smp_read_barrier_depends(); \
-                (_________p1); \
-        })
+({ \
+        typeof(p) _________p1 = ACCESS_ONCE(p); \
+        rcu_lockdep_assert(c, \
+                           "suspicious rcu_dereference_index_check() usage"); \
+        smp_read_barrier_depends(); /* Dependency order vs. p above. */ \
+        (_________p1); \
+})
 
 /**
  * RCU_INITIALIZER() - statically initialize an RCU-protected global variable
@@ -585,12 +582,7 @@ static inline void rcu_preempt_sleep_check(void)
  * please be careful when making changes to rcu_assign_pointer() and the
  * other macros that it invokes.
  */
-#define rcu_assign_pointer(p, v) \
-        do { \
-                smp_wmb(); \
-                ACCESS_ONCE(p) = RCU_INITIALIZER(v); \
-        } while (0)
-
+#define rcu_assign_pointer(p, v) smp_store_release(&p, RCU_INITIALIZER(v))
 
 /**
  * rcu_access_pointer() - fetch RCU pointer with no dereferencing
@@ -1015,11 +1007,21 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
 #define kfree_rcu(ptr, rcu_head)                                        \
         __kfree_rcu(&((ptr)->rcu_head), offsetof(typeof(*(ptr)), rcu_head))
 
-#ifdef CONFIG_RCU_NOCB_CPU
+#if defined(CONFIG_TINY_RCU) || defined(CONFIG_RCU_NOCB_CPU_ALL)
+static inline int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
+{
+        *delta_jiffies = ULONG_MAX;
+        return 0;
+}
+#endif /* #if defined(CONFIG_TINY_RCU) || defined(CONFIG_RCU_NOCB_CPU_ALL) */
+
+#if defined(CONFIG_RCU_NOCB_CPU_ALL)
+static inline bool rcu_is_nocb_cpu(int cpu) { return true; }
+#elif defined(CONFIG_RCU_NOCB_CPU)
 bool rcu_is_nocb_cpu(int cpu);
 #else
 static inline bool rcu_is_nocb_cpu(int cpu) { return false; }
-#endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */
+#endif
 
 
 /* Only for use by adaptive-ticks code. */
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index 6f01771b571c..e8cb6e3b52a7 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -12,8 +12,8 @@
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ * along with this program; if not, you can access it online at
+ * http://www.gnu.org/licenses/gpl-2.0.html.
  *
  * Copyright IBM Corporation, 2008
  *
@@ -68,12 +68,6 @@ static inline void kfree_call_rcu(struct rcu_head *head,
         call_rcu(head, func);
 }
 
-static inline int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
-{
-        *delta_jiffies = ULONG_MAX;
-        return 0;
-}
-
 static inline void rcu_note_context_switch(int cpu)
 {
         rcu_sched_qs(cpu);
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index 72137ee8c603..e9c63884df0a 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -12,8 +12,8 @@
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ * along with this program; if not, you can access it online at
+ * http://www.gnu.org/licenses/gpl-2.0.html.
  *
  * Copyright IBM Corporation, 2008
  *
@@ -31,7 +31,9 @@
 #define __LINUX_RCUTREE_H
 
 void rcu_note_context_switch(int cpu);
+#ifndef CONFIG_RCU_NOCB_CPU_ALL
 int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies);
+#endif /* #ifndef CONFIG_RCU_NOCB_CPU_ALL */
 void rcu_cpu_stall_reset(void);
 
 /*
diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index 9b058eecd403..a2783cb5d275 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -12,8 +12,8 @@
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ * along with this program; if not, you can access it online at
+ * http://www.gnu.org/licenses/gpl-2.0.html.
  *
  * Copyright (C) IBM Corporation, 2006
  * Copyright (C) Fujitsu, 2012
diff --git a/include/linux/torture.h b/include/linux/torture.h
new file mode 100644
index 000000000000..b2e2b468e511
--- /dev/null
+++ b/include/linux/torture.h
@@ -0,0 +1,100 @@
+/*
+ * Common functions for in-kernel torture tests.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, you can access it online at
+ * http://www.gnu.org/licenses/gpl-2.0.html.
+ *
+ * Copyright IBM Corporation, 2014
+ *
+ * Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+ */
+
+#ifndef __LINUX_TORTURE_H
+#define __LINUX_TORTURE_H
+
+#include <linux/types.h>
+#include <linux/cache.h>
+#include <linux/spinlock.h>
+#include <linux/threads.h>
+#include <linux/cpumask.h>
+#include <linux/seqlock.h>
+#include <linux/lockdep.h>
+#include <linux/completion.h>
+#include <linux/debugobjects.h>
+#include <linux/bug.h>
+#include <linux/compiler.h>
+
+/* Definitions for a non-string torture-test module parameter. */
+#define torture_param(type, name, init, msg) \
+        static type name = init; \
+        module_param(name, type, 0444); \
+        MODULE_PARM_DESC(name, msg);
+
+#define TORTURE_FLAG "-torture:"
+#define TOROUT_STRING(s) \
+        pr_alert("%s" TORTURE_FLAG s "\n", torture_type)
+#define VERBOSE_TOROUT_STRING(s) \
+        do { if (verbose) pr_alert("%s" TORTURE_FLAG " %s\n", torture_type, s); } while (0)
+#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);
+bool torture_onoff_failures(void);
+
+/* Low-rider random number generator. */
+struct torture_random_state {
+        unsigned long trs_state;
+        long trs_count;
+};
+#define DEFINE_TORTURE_RANDOM(name) struct torture_random_state name = { 0, 0 }
+unsigned long torture_random(struct torture_random_state *trsp);
+
+/* Task shuffler, which causes CPUs to occasionally go idle. */
+void torture_shuffle_task_register(struct task_struct *tp);
+int torture_shuffle_init(long shuffint);
+
+/* Test auto-shutdown handling. */
+void torture_shutdown_absorb(const char *title);
+int torture_shutdown_init(int ssecs, void (*cleanup)(void));
+
+/* Task stuttering, which forces load/no-load transitions. */
+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);
+void torture_init_end(void);
+bool torture_cleanup(void);
+bool torture_must_stop(void);
+bool torture_must_stop_irq(void);
+void torture_kthread_stopping(char *title);
+int _torture_create_kthread(int (*fn)(void *arg), void *arg, char *s, char *m,
+                             char *f, struct task_struct **tp);
+void _torture_stop_kthread(char *m, struct task_struct **tp);
+
+#define torture_create_kthread(n, arg, tp) \
+        _torture_create_kthread(n, (arg), #n, "Creating " #n " task", \
+                                "Failed to create " #n, &(tp))
+#define torture_stop_kthread(n, tp) \
+        _torture_stop_kthread("Stopping " #n " task", &(tp))
+
+#endif /* __LINUX_TORTURE_H */