rcu: Remove TINY_PREEMPT_RCU
TINY_PREEMPT_RCU adds significant code and complexity, but does not
offer commensurate benefits. People currently using TINY_PREEMPT_RCU
can get much better memory footprint with TINY_RCU, or, if they really
need preemptible RCU, they can use TREE_PREEMPT_RCU with a relatively
minor degradation in memory footprint. Please note that this move
has been widely publicized on LKML (https://lkml.org/lkml/2012/11/12/545)
and on LWN (http://lwn.net/Articles/541037/).
This commit therefore removes TINY_PREEMPT_RCU.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
[ paulmck: Updated to eliminate #else in rcutiny.h as suggested by Josh ]
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
index c1d6555..05bcc09 100644
--- a/include/linux/hardirq.h
+++ b/include/linux/hardirq.h
@@ -128,7 +128,7 @@
# define synchronize_irq(irq) barrier()
#endif
-#if defined(CONFIG_TINY_RCU) || defined(CONFIG_TINY_PREEMPT_RCU)
+#if defined(CONFIG_TINY_RCU)
static inline void rcu_nmi_enter(void)
{
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index ddcc782..70b1522 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -277,7 +277,7 @@
#if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU)
#include <linux/rcutree.h>
-#elif defined(CONFIG_TINY_RCU) || defined(CONFIG_TINY_PREEMPT_RCU)
+#elif defined(CONFIG_TINY_RCU)
#include <linux/rcutiny.h>
#else
#error "Unknown RCU implementation specified to kernel configuration"
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index 4e56a9c..d3c094f 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -53,16 +53,7 @@
rcu_barrier_sched(); /* Only one CPU, so only one list of callbacks! */
}
-#else /* #ifdef CONFIG_TINY_RCU */
-
-void synchronize_rcu_expedited(void);
-
-static inline void rcu_barrier(void)
-{
- wait_rcu_gp(call_rcu);
-}
-
-#endif /* #else #ifdef CONFIG_TINY_RCU */
+#endif /* #ifdef CONFIG_TINY_RCU */
static inline void synchronize_rcu_bh(void)
{
@@ -97,18 +88,7 @@
return 0;
}
-#else /* #ifdef CONFIG_TINY_RCU */
-
-void rcu_preempt_note_context_switch(void);
-int rcu_preempt_needs_cpu(void);
-
-static inline int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
-{
- *delta_jiffies = ULONG_MAX;
- return rcu_preempt_needs_cpu();
-}
-
-#endif /* #else #ifdef CONFIG_TINY_RCU */
+#endif /* #ifdef CONFIG_TINY_RCU */
static inline void rcu_note_context_switch(int cpu)
{
