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authorLinus Torvalds <torvalds@linux-foundation.org>2014-07-19 06:23:27 -1000
committerLinus Torvalds <torvalds@linux-foundation.org>2014-07-19 06:23:27 -1000
commitda5b99b4545e2bae9a08876e6e827589dbfdcd9a (patch)
tree7a4ad7ba3f36080b94d4cf58c15f5314e36479ab /include
parentd614cb0bc3c991710a7bbb5496e990550cb08180 (diff)
parent5cfec3422adcc1987a1b5fc5ff59ad42a1bc910e (diff)
Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU fixes from Thomas Gleixner: "Two RCU patches: - Address a serious performance regression on open/close caused by commit ac1bea85781e ("Make cond_resched() report RCU quiescent states") - Export RCU debug functions. Not a regression, but enablement to address a serious recursion bug in the sl*b allocators in 3.17" * 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: rcu: Reduce overhead of cond_resched() checks for RCU rcu: Export debug_init_rcu_head() and and debug_init_rcu_head()
Diffstat (limited to 'include')
-rw-r--r--include/linux/rcupdate.h46
1 files changed, 10 insertions, 36 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 5a75d19aa661..6a94cc8b1ca0 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -44,7 +44,6 @@
#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 */
@@ -300,41 +299,6 @@ 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.
*/
@@ -358,9 +322,19 @@ void wait_rcu_gp(call_rcu_func_t crf);
* initialization.
*/
#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
+void init_rcu_head(struct rcu_head *head);
+void destroy_rcu_head(struct rcu_head *head);
void init_rcu_head_on_stack(struct rcu_head *head);
void destroy_rcu_head_on_stack(struct rcu_head *head);
#else /* !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
+static inline void init_rcu_head(struct rcu_head *head)
+{
+}
+
+static inline void destroy_rcu_head(struct rcu_head *head)
+{
+}
+
static inline void init_rcu_head_on_stack(struct rcu_head *head)
{
}