Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull RCU updates from Ingo Molnar:
 "The RCU changes in this cycle were:
   - Expedited grace-period updates
   - kfree_rcu() updates
   - RCU list updates
   - Preemptible RCU updates
   - Torture-test updates
   - Miscellaneous fixes
   - Documentation updates"

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (69 commits)
  rcu: Remove unused stop-machine #include
  powerpc: Remove comment about read_barrier_depends()
  .mailmap: Add entries for old paulmck@kernel.org addresses
  srcu: Apply *_ONCE() to ->srcu_last_gp_end
  rcu: Switch force_qs_rnp() to for_each_leaf_node_cpu_mask()
  rcu: Move rcu_{expedited,normal} definitions into rcupdate.h
  rcu: Move gp_state_names[] and gp_state_getname() to tree_stall.h
  rcu: Remove the declaration of call_rcu() in tree.h
  rcu: Fix tracepoint tracking RCU CPU kthread utilization
  rcu: Fix harmless omission of "CONFIG_" from #if condition
  rcu: Avoid tick_dep_set_cpu() misordering
  rcu: Provide wrappers for uses of ->rcu_read_lock_nesting
  rcu: Use READ_ONCE() for ->expmask in rcu_read_unlock_special()
  rcu: Clear ->rcu_read_unlock_special only once
  rcu: Clear .exp_hint only when deferred quiescent state has been reported
  rcu: Rename some instance of CONFIG_PREEMPTION to CONFIG_PREEMPT_RCU
  rcu: Remove kfree_call_rcu_nobatch()
  rcu: Remove kfree_rcu() special casing and lazy-callback handling
  rcu: Add support for debug_objects debugging for kfree_rcu()
  rcu: Add multiple in-flight batches of kfree_rcu() work
  ...

1 files changed, 27 insertions, 1 deletions

diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c
index 477b4eb44af5..dd572ce7c747 100644
--- a/kernel/rcu/tiny.c
+++ b/kernel/rcu/tiny.c
@@ -22,6 +22,7 @@
 #include <linux/time.h>
 #include <linux/cpu.h>
 #include <linux/prefetch.h>
+#include <linux/slab.h>
 
 #include "rcu.h"
 
@@ -73,6 +74,31 @@ void rcu_sched_clock_irq(int user)
 	}
 }
 
+/*
+ * Reclaim the specified callback, either by invoking it for non-kfree cases or
+ * freeing it directly (for kfree). Return true if kfreeing, false otherwise.
+ */
+static inline bool rcu_reclaim_tiny(struct rcu_head *head)
+{
+	rcu_callback_t f;
+	unsigned long offset = (unsigned long)head->func;
+
+	rcu_lock_acquire(&rcu_callback_map);
+	if (__is_kfree_rcu_offset(offset)) {
+		trace_rcu_invoke_kfree_callback("", head, offset);
+		kfree((void *)head - offset);
+		rcu_lock_release(&rcu_callback_map);
+		return true;
+	}
+
+	trace_rcu_invoke_callback("", head);
+	f = head->func;
+	WRITE_ONCE(head->func, (rcu_callback_t)0L);
+	f(head);
+	rcu_lock_release(&rcu_callback_map);
+	return false;
+}
+
 /* Invoke the RCU callbacks whose grace period has elapsed.  */
 static __latent_entropy void rcu_process_callbacks(struct softirq_action *unused)
 {
@@ -100,7 +126,7 @@ static __latent_entropy void rcu_process_callbacks(struct softirq_action *unused
 		prefetch(next);
 		debug_rcu_head_unqueue(list);
 		local_bh_disable();
-		__rcu_reclaim("", list);
+		rcu_reclaim_tiny(list);
 		local_bh_enable();
 		list = next;
 	}