rcu: Make PREEMPT_RCU be a modifier to TREE_RCU

Currently PREEMPT_RCU and TREE_RCU are mutually exclusive Kconfig
options.  But PREEMPT_RCU actually specifies a kind of TREE_RCU,
namely a preemptible TREE_RCU. This commit therefore makes PREEMPT_RCU
be a modifer to the TREE_RCU Kconfig option.  This has the benefit of
simplifying several of the #if expressions that formerly needed to
check both, but now need only check one or the other.

Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Lai Jiangshan <jiangshanlai@gmail.com>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 0b75063..70a41cd 100644 (file)
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -167,7 +167,7 @@ do { \
  * TREE_RCU and rcu_barrier_() primitives in TINY_RCU.
  */
 
-#if defined(CONFIG_TREE_RCU) || defined(CONFIG_PREEMPT_RCU)
+#if defined(CONFIG_TREE_RCU)
 #include <linux/rcutree.h>
 #elif defined(CONFIG_TINY_RCU)
 #include <linux/rcutiny.h>
@@ -601,7 +601,7 @@ do {                                                                              \
  * read-side critical section that would block in a !PREEMPT kernel.
  * But if you want the full story, read on!
  *
- * In non-preemptible RCU implementations (TREE_RCU and TINY_RCU),
+ * In non-preemptible RCU implementations (pure TREE_RCU and TINY_RCU),
  * it is illegal to block while in an RCU read-side critical section.
  * In preemptible RCU implementations (PREEMPT_RCU) in CONFIG_PREEMPTION
  * kernel builds, RCU read-side critical sections may be preempted,

diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h
index 6612260..85019cf 100644 (file)
--- a/include/trace/events/rcu.h
+++ b/include/trace/events/rcu.h
@@ -41,7 +41,7 @@ TRACE_EVENT(rcu_utilization,
        TP_printk("%s", __entry->s)
 );
 
-#if defined(CONFIG_TREE_RCU) || defined(CONFIG_PREEMPT_RCU)
+#if defined(CONFIG_TREE_RCU)
 
 /*
  * Tracepoint for grace-period events.  Takes a string identifying the
@@ -432,7 +432,7 @@ TRACE_EVENT_RCU(rcu_fqs,
                  __entry->cpu, __entry->qsevent)
 );
 
-#endif /* #if defined(CONFIG_TREE_RCU) || defined(CONFIG_PREEMPT_RCU) */
+#endif /* #if defined(CONFIG_TREE_RCU) */
 
 /*
  * Tracepoint for dyntick-idle entry/exit events.  These take a string

diff --git a/kernel/rcu/Kconfig b/kernel/rcu/Kconfig
index 7644eda..0303934 100644 (file)
--- a/kernel/rcu/Kconfig
+++ b/kernel/rcu/Kconfig
@@ -7,7 +7,7 @@ menu "RCU Subsystem"
 
 config TREE_RCU
        bool
-       default y if !PREEMPTION && SMP
+       default y if SMP
        help
          This option selects the RCU implementation that is
          designed for very large SMP system with hundreds or
@@ -17,6 +17,7 @@ config TREE_RCU
 config PREEMPT_RCU
        bool
        default y if PREEMPTION
+       select TREE_RCU
        help
          This option selects the RCU implementation that is
          designed for very large SMP systems with hundreds or
@@ -78,7 +79,7 @@ config TASKS_RCU
          user-mode execution as quiescent states.
 
 config RCU_STALL_COMMON
-       def_bool ( TREE_RCU || PREEMPT_RCU )
+       def_bool TREE_RCU
        help
          This option enables RCU CPU stall code that is common between
          the TINY and TREE variants of RCU.  The purpose is to allow
@@ -86,13 +87,13 @@ config RCU_STALL_COMMON
          making these warnings mandatory for the tree variants.
 
 config RCU_NEED_SEGCBLIST
-       def_bool ( TREE_RCU || PREEMPT_RCU || TREE_SRCU )
+       def_bool ( TREE_RCU || TREE_SRCU )
 
 config RCU_FANOUT
        int "Tree-based hierarchical RCU fanout value"
        range 2 64 if 64BIT
        range 2 32 if !64BIT
-       depends on (TREE_RCU || PREEMPT_RCU) && RCU_EXPERT
+       depends on TREE_RCU && RCU_EXPERT
        default 64 if 64BIT
        default 32 if !64BIT
        help
@@ -112,7 +113,7 @@ config RCU_FANOUT_LEAF
        int "Tree-based hierarchical RCU leaf-level fanout value"
        range 2 64 if 64BIT
        range 2 32 if !64BIT
-       depends on (TREE_RCU || PREEMPT_RCU) && RCU_EXPERT
+       depends on TREE_RCU && RCU_EXPERT
        default 16
        help
          This option controls the leaf-level fanout of hierarchical
@@ -187,7 +188,7 @@ config RCU_BOOST_DELAY
 
 config RCU_NOCB_CPU
        bool "Offload RCU callback processing from boot-selected CPUs"
-       depends on TREE_RCU || PREEMPT_RCU
+       depends on TREE_RCU
        depends on RCU_EXPERT || NO_HZ_FULL
        default n
        help

diff --git a/kernel/rcu/Makefile b/kernel/rcu/Makefile
index 020e8b6..82d5fba 100644 (file)
--- a/kernel/rcu/Makefile
+++ b/kernel/rcu/Makefile
@@ -9,6 +9,5 @@ obj-$(CONFIG_TINY_SRCU) += srcutiny.o
 obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o
 obj-$(CONFIG_RCU_PERF_TEST) += rcuperf.o
 obj-$(CONFIG_TREE_RCU) += tree.o
-obj-$(CONFIG_PREEMPT_RCU) += tree.o
 obj-$(CONFIG_TINY_RCU) += tiny.o
 obj-$(CONFIG_RCU_NEED_SEGCBLIST) += rcu_segcblist.o

diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h
index ab504fb..eabafde 100644 (file)
--- a/kernel/rcu/rcu.h
+++ b/kernel/rcu/rcu.h
@@ -454,7 +454,7 @@ enum rcutorture_type {
        INVALID_RCU_FLAVOR
 };
 
-#if defined(CONFIG_TREE_RCU) || defined(CONFIG_PREEMPT_RCU)
+#if defined(CONFIG_TREE_RCU)
 void rcutorture_get_gp_data(enum rcutorture_type test_type, int *flags,
                            unsigned long *gp_seq);
 void do_trace_rcu_torture_read(const char *rcutorturename,

diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 1861103..34a7452 100644 (file)
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -435,7 +435,7 @@ struct debug_obj_descr rcuhead_debug_descr = {
 EXPORT_SYMBOL_GPL(rcuhead_debug_descr);
 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
 
-#if defined(CONFIG_TREE_RCU) || defined(CONFIG_PREEMPT_RCU) || defined(CONFIG_RCU_TRACE)
+#if defined(CONFIG_TREE_RCU) || defined(CONFIG_RCU_TRACE)
 void do_trace_rcu_torture_read(const char *rcutorturename, struct rcu_head *rhp,
                               unsigned long secs,
                               unsigned long c_old, unsigned long c)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 7066593..d396aaa 100644 (file)
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1268,7 +1268,7 @@ static struct ctl_table kern_table[] = {
                .proc_handler   = proc_do_static_key,
        },
 #endif
-#if defined(CONFIG_TREE_RCU) || defined(CONFIG_PREEMPT_RCU)
+#if defined(CONFIG_TREE_RCU)
        {
                .procname       = "panic_on_rcu_stall",
                .data           = &sysctl_panic_on_rcu_stall,