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

Pull RCU changes from Paul E. McKenney:

- Convert RCU's BUG_ON() and similar calls to WARN_ON() and similar.

- Replace calls of RCU-bh and RCU-sched update-side functions
  to their vanilla RCU counterparts.  This series is a step
  towards complete removal of the RCU-bh and RCU-sched update-side
  functions.

  ( Note that some of these conversions are going upstream via their
    respective maintainers. )

- Documentation updates, including a number of flavor-consolidation
  updates from Joel Fernandes.

- Miscellaneous fixes.

- Automate generation of the initrd filesystem used for
  rcutorture testing.

- Convert spin_is_locked() assertions to instead use lockdep.

  ( Note that some of these conversions are going upstream via their
    respective maintainers. )

- SRCU updates, especially including a fix from Dennis Krein
  for a bag-on-head-class bug.

- RCU torture-test updates.

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

8 files changed, 64 insertions, 76 deletions

diff --git a/include/linux/percpu-rwsem.h b/include/linux/percpu-rwsem.h
index 79b99d653e03..71b75643c432 100644
--- a/include/linux/percpu-rwsem.h
+++ b/include/linux/percpu-rwsem.h
@@ -41,7 +41,7 @@ static inline void percpu_down_read_preempt_disable(struct percpu_rw_semaphore *
          * cannot both change sem->state from readers_fast and start checking
          * counters while we are here. So if we see !sem->state, we know that
          * the writer won't be checking until we're past the preempt_enable()
-         * and that one the synchronize_sched() is done, the writer will see
+         * and that once the synchronize_rcu() is done, the writer will see
          * anything we did within this RCU-sched read-size critical section.
          */
         __this_cpu_inc(*sem->read_count);
diff --git a/include/linux/rcupdate_wait.h b/include/linux/rcupdate_wait.h
index 8a16c3eb3dd0..c0578ba23c1a 100644
--- a/include/linux/rcupdate_wait.h
+++ b/include/linux/rcupdate_wait.h
@@ -31,21 +31,4 @@ do {									\
 
 #define wait_rcu_gp(...) _wait_rcu_gp(false, __VA_ARGS__)
 
-/**
- * synchronize_rcu_mult - Wait concurrently for multiple grace periods
- * @...: List of call_rcu() functions for different grace periods to wait on
- *
- * This macro waits concurrently for multiple types of RCU grace periods.
- * For example, synchronize_rcu_mult(call_rcu, call_rcu_tasks) would wait
- * on concurrent RCU and RCU-tasks grace periods.  Waiting on a give SRCU
- * domain requires you to write a wrapper function for that SRCU domain's
- * call_srcu() function, supplying the corresponding srcu_struct.
- *
- * If Tiny RCU, tell _wait_rcu_gp() does not bother waiting for RCU,
- * given that anywhere synchronize_rcu_mult() can be called is automatically
- * a grace period.
- */
-#define synchronize_rcu_mult(...) \
-        _wait_rcu_gp(IS_ENABLED(CONFIG_TINY_RCU), __VA_ARGS__)
-
 #endif /* _LINUX_SCHED_RCUPDATE_WAIT_H */
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 291a9bd5b97f..4f8fc5294291 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -572,8 +572,10 @@ union rcu_special {
         struct {
                 u8                      blocked;
                 u8                      need_qs;
+                u8                      exp_hint; /* Hint for performance. */
+                u8                      pad; /* No garbage from compiler! */
         } b; /* Bits. */
-        u16 s; /* Set of bits. */
+        u32 s; /* Set of bits. */
 };
 
 enum perf_event_task_context {
diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index 67135d4a8a30..c614375cd264 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -38,20 +38,20 @@ struct srcu_struct;
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 
-int __init_srcu_struct(struct srcu_struct *sp, const char *name,
+int __init_srcu_struct(struct srcu_struct *ssp, const char *name,
                        struct lock_class_key *key);
 
-#define init_srcu_struct(sp) \
+#define init_srcu_struct(ssp) \
 ({ \
         static struct lock_class_key __srcu_key; \
         \
-        __init_srcu_struct((sp), #sp, &__srcu_key); \
+        __init_srcu_struct((ssp), #ssp, &__srcu_key); \
 })
 
 #define __SRCU_DEP_MAP_INIT(srcu_name)  .dep_map = { .name = #srcu_name },
 #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 
-int init_srcu_struct(struct srcu_struct *sp);
+int init_srcu_struct(struct srcu_struct *ssp);
 
 #define __SRCU_DEP_MAP_INIT(srcu_name)
 #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
@@ -67,28 +67,28 @@ int init_srcu_struct(struct srcu_struct *sp);
 struct srcu_struct { };
 #endif
 
-void call_srcu(struct srcu_struct *sp, struct rcu_head *head,
+void call_srcu(struct srcu_struct *ssp, struct rcu_head *head,
                 void (*func)(struct rcu_head *head));
-void _cleanup_srcu_struct(struct srcu_struct *sp, bool quiesced);
-int __srcu_read_lock(struct srcu_struct *sp) __acquires(sp);
-void __srcu_read_unlock(struct srcu_struct *sp, int idx) __releases(sp);
-void synchronize_srcu(struct srcu_struct *sp);
+void _cleanup_srcu_struct(struct srcu_struct *ssp, bool quiesced);
+int __srcu_read_lock(struct srcu_struct *ssp) __acquires(ssp);
+void __srcu_read_unlock(struct srcu_struct *ssp, int idx) __releases(ssp);
+void synchronize_srcu(struct srcu_struct *ssp);
 
 /**
  * cleanup_srcu_struct - deconstruct a sleep-RCU structure
- * @sp: structure to clean up.
+ * @ssp: structure to clean up.
  *
  * Must invoke this after you are finished using a given srcu_struct that
  * was initialized via init_srcu_struct(), else you leak memory.
  */
-static inline void cleanup_srcu_struct(struct srcu_struct *sp)
+static inline void cleanup_srcu_struct(struct srcu_struct *ssp)
 {
-        _cleanup_srcu_struct(sp, false);
+        _cleanup_srcu_struct(ssp, false);
 }
 
 /**
  * cleanup_srcu_struct_quiesced - deconstruct a quiesced sleep-RCU structure
- * @sp: structure to clean up.
+ * @ssp: structure to clean up.
  *
  * Must invoke this after you are finished using a given srcu_struct that
  * was initialized via init_srcu_struct(), else you leak memory.  Also,
@@ -103,16 +103,16 @@ static inline void cleanup_srcu_struct(struct srcu_struct *sp)
  * (with high probability, anyway), and will also cause the srcu_struct
  * to be leaked.
  */
-static inline void cleanup_srcu_struct_quiesced(struct srcu_struct *sp)
+static inline void cleanup_srcu_struct_quiesced(struct srcu_struct *ssp)
 {
-        _cleanup_srcu_struct(sp, true);
+        _cleanup_srcu_struct(ssp, true);
 }
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 
 /**
  * srcu_read_lock_held - might we be in SRCU read-side critical section?
- * @sp: The srcu_struct structure to check
+ * @ssp: The srcu_struct structure to check
  *
  * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an SRCU
  * read-side critical section.  In absence of CONFIG_DEBUG_LOCK_ALLOC,
@@ -126,16 +126,16 @@ static inline void cleanup_srcu_struct_quiesced(struct srcu_struct *sp)
  * relies on normal RCU, it can be called from the CPU which
  * is in the idle loop from an RCU point of view or offline.
  */
-static inline int srcu_read_lock_held(const struct srcu_struct *sp)
+static inline int srcu_read_lock_held(const struct srcu_struct *ssp)
 {
         if (!debug_lockdep_rcu_enabled())
                 return 1;
-        return lock_is_held(&sp->dep_map);
+        return lock_is_held(&ssp->dep_map);
 }
 
 #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 
-static inline int srcu_read_lock_held(const struct srcu_struct *sp)
+static inline int srcu_read_lock_held(const struct srcu_struct *ssp)
 {
         return 1;
 }
@@ -145,7 +145,7 @@ static inline int srcu_read_lock_held(const struct srcu_struct *sp)
 /**
  * srcu_dereference_check - fetch SRCU-protected pointer for later dereferencing
  * @p: the pointer to fetch and protect for later dereferencing
- * @sp: pointer to the srcu_struct, which is used to check that we
+ * @ssp: pointer to the srcu_struct, which is used to check that we
  *      really are in an SRCU read-side critical section.
  * @c: condition to check for update-side use
  *
@@ -154,29 +154,32 @@ static inline int srcu_read_lock_held(const struct srcu_struct *sp)
  * to 1.  The @c argument will normally be a logical expression containing
  * lockdep_is_held() calls.
  */
-#define srcu_dereference_check(p, sp, c) \
-        __rcu_dereference_check((p), (c) || srcu_read_lock_held(sp), __rcu)
+#define srcu_dereference_check(p, ssp, c) \
+        __rcu_dereference_check((p), (c) || srcu_read_lock_held(ssp), __rcu)
 
 /**
  * srcu_dereference - fetch SRCU-protected pointer for later dereferencing
  * @p: the pointer to fetch and protect for later dereferencing
- * @sp: pointer to the srcu_struct, which is used to check that we
+ * @ssp: pointer to the srcu_struct, which is used to check that we
  *      really are in an SRCU read-side critical section.
  *
  * Makes rcu_dereference_check() do the dirty work.  If PROVE_RCU
  * is enabled, invoking this outside of an RCU read-side critical
  * section will result in an RCU-lockdep splat.
  */
-#define srcu_dereference(p, sp) srcu_dereference_check((p), (sp), 0)
+#define srcu_dereference(p, ssp) srcu_dereference_check((p), (ssp), 0)
 
 /**
  * srcu_dereference_notrace - no tracing and no lockdep calls from here
+ * @p: the pointer to fetch and protect for later dereferencing
+ * @ssp: pointer to the srcu_struct, which is used to check that we
+ *      really are in an SRCU read-side critical section.
  */
-#define srcu_dereference_notrace(p, sp) srcu_dereference_check((p), (sp), 1)
+#define srcu_dereference_notrace(p, ssp) srcu_dereference_check((p), (ssp), 1)
 
 /**
  * srcu_read_lock - register a new reader for an SRCU-protected structure.
- * @sp: srcu_struct in which to register the new reader.
+ * @ssp: srcu_struct in which to register the new reader.
  *
  * Enter an SRCU read-side critical section.  Note that SRCU read-side
  * critical sections may be nested.  However, it is illegal to
@@ -191,44 +194,44 @@ static inline int srcu_read_lock_held(const struct srcu_struct *sp)
  * srcu_read_unlock() in an irq handler if the matching srcu_read_lock()
  * was invoked in process context.
  */
-static inline int srcu_read_lock(struct srcu_struct *sp) __acquires(sp)
+static inline int srcu_read_lock(struct srcu_struct *ssp) __acquires(ssp)
 {
         int retval;
 
-        retval = __srcu_read_lock(sp);
-        rcu_lock_acquire(&(sp)->dep_map);
+        retval = __srcu_read_lock(ssp);
+        rcu_lock_acquire(&(ssp)->dep_map);
         return retval;
 }
 
 /* Used by tracing, cannot be traced and cannot invoke lockdep. */
 static inline notrace int
-srcu_read_lock_notrace(struct srcu_struct *sp) __acquires(sp)
+srcu_read_lock_notrace(struct srcu_struct *ssp) __acquires(ssp)
 {
         int retval;
 
-        retval = __srcu_read_lock(sp);
+        retval = __srcu_read_lock(ssp);
         return retval;
 }
 
 /**
  * srcu_read_unlock - unregister a old reader from an SRCU-protected structure.
- * @sp: srcu_struct in which to unregister the old reader.
+ * @ssp: srcu_struct in which to unregister the old reader.
  * @idx: return value from corresponding srcu_read_lock().
  *
  * Exit an SRCU read-side critical section.
  */
-static inline void srcu_read_unlock(struct srcu_struct *sp, int idx)
-        __releases(sp)
+static inline void srcu_read_unlock(struct srcu_struct *ssp, int idx)
+        __releases(ssp)
 {
-        rcu_lock_release(&(sp)->dep_map);
-        __srcu_read_unlock(sp, idx);
+        rcu_lock_release(&(ssp)->dep_map);
+        __srcu_read_unlock(ssp, idx);
 }
 
 /* Used by tracing, cannot be traced and cannot call lockdep. */
 static inline notrace void
-srcu_read_unlock_notrace(struct srcu_struct *sp, int idx) __releases(sp)
+srcu_read_unlock_notrace(struct srcu_struct *ssp, int idx) __releases(ssp)
 {
-        __srcu_read_unlock(sp, idx);
+        __srcu_read_unlock(ssp, idx);
 }
 
 /**
diff --git a/include/linux/srcutiny.h b/include/linux/srcutiny.h
index f41d2fb09f87..b19216aaaef2 100644
--- a/include/linux/srcutiny.h
+++ b/include/linux/srcutiny.h
@@ -60,7 +60,7 @@ void srcu_drive_gp(struct work_struct *wp);
 #define DEFINE_STATIC_SRCU(name) \
         static struct srcu_struct name = __SRCU_STRUCT_INIT(name, name)
 
-void synchronize_srcu(struct srcu_struct *sp);
+void synchronize_srcu(struct srcu_struct *ssp);
 
 /*
  * Counts the new reader in the appropriate per-CPU element of the
@@ -68,36 +68,36 @@ void synchronize_srcu(struct srcu_struct *sp);
  * __srcu_read_unlock() must be in the same handler instance.  Returns an
  * index that must be passed to the matching srcu_read_unlock().
  */
-static inline int __srcu_read_lock(struct srcu_struct *sp)
+static inline int __srcu_read_lock(struct srcu_struct *ssp)
 {
         int idx;
 
-        idx = READ_ONCE(sp->srcu_idx);
-        WRITE_ONCE(sp->srcu_lock_nesting[idx], sp->srcu_lock_nesting[idx] + 1);
+        idx = READ_ONCE(ssp->srcu_idx);
+        WRITE_ONCE(ssp->srcu_lock_nesting[idx], ssp->srcu_lock_nesting[idx] + 1);
         return idx;
 }
 
-static inline void synchronize_srcu_expedited(struct srcu_struct *sp)
+static inline void synchronize_srcu_expedited(struct srcu_struct *ssp)
 {
-        synchronize_srcu(sp);
+        synchronize_srcu(ssp);
 }
 
-static inline void srcu_barrier(struct srcu_struct *sp)
+static inline void srcu_barrier(struct srcu_struct *ssp)
 {
-        synchronize_srcu(sp);
+        synchronize_srcu(ssp);
 }
 
 /* Defined here to avoid size increase for non-torture kernels. */
-static inline void srcu_torture_stats_print(struct srcu_struct *sp,
+static inline void srcu_torture_stats_print(struct srcu_struct *ssp,
                                             char *tt, char *tf)
 {
         int idx;
 
-        idx = READ_ONCE(sp->srcu_idx) & 0x1;
+        idx = READ_ONCE(ssp->srcu_idx) & 0x1;
         pr_alert("%s%s Tiny SRCU per-CPU(idx=%d): (%hd,%hd)\n",
                  tt, tf, idx,
-                 READ_ONCE(sp->srcu_lock_nesting[!idx]),
-                 READ_ONCE(sp->srcu_lock_nesting[idx]));
+                 READ_ONCE(ssp->srcu_lock_nesting[!idx]),
+                 READ_ONCE(ssp->srcu_lock_nesting[idx]));
 }
 
 #endif
diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h
index 0ae91b3a7406..6f292bd3e7db 100644
--- a/include/linux/srcutree.h
+++ b/include/linux/srcutree.h
@@ -51,7 +51,7 @@ struct srcu_data {
         unsigned long grpmask;                  /* Mask for leaf srcu_node */
                                                 /*  ->srcu_data_have_cbs[]. */
         int cpu;
-        struct srcu_struct *sp;
+        struct srcu_struct *ssp;
 };
 
 /*
@@ -138,8 +138,8 @@ struct srcu_struct {
 #define DEFINE_SRCU(name)               __DEFINE_SRCU(name, /* not static */)
 #define DEFINE_STATIC_SRCU(name)        __DEFINE_SRCU(name, static)
 
-void synchronize_srcu_expedited(struct srcu_struct *sp);
-void srcu_barrier(struct srcu_struct *sp);
-void srcu_torture_stats_print(struct srcu_struct *sp, char *tt, char *tf);
+void synchronize_srcu_expedited(struct srcu_struct *ssp);
+void srcu_barrier(struct srcu_struct *ssp);
+void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf);
 
 #endif
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index e9de8ad0bad7..9c3186578ce0 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -82,7 +82,7 @@ int unregister_tracepoint_module_notifier(struct notifier_block *nb)
 static inline void tracepoint_synchronize_unregister(void)
 {
         synchronize_srcu(&tracepoint_srcu);
-        synchronize_sched();
+        synchronize_rcu();
 }
 #else
 static inline void tracepoint_synchronize_unregister(void)
diff --git a/include/linux/types.h b/include/linux/types.h
index 9834e90aa010..c2615d6a019e 100644
--- a/include/linux/types.h
+++ b/include/linux/types.h
@@ -212,8 +212,8 @@ struct ustat {
  * weird ABI and we need to ask it explicitly.
  *
  * The alignment is required to guarantee that bit 0 of @next will be
- * clear under normal conditions -- as long as we use call_rcu(),
- * call_rcu_bh(), call_rcu_sched(), or call_srcu() to queue callback.
+ * clear under normal conditions -- as long as we use call_rcu() or
+ * call_srcu() to queue the callback.
  *
  * This guarantee is important for few reasons:
  *  - future call_rcu_lazy() will make use of lower bits in the pointer;