[tip: core/rcu] rcu: Make PREEMPT_RCU be a modifier to TREE_RCU

From: tip-bot2 for Lai Jiangshan
Date: Sat Jan 25 2020 - 05:45:14 EST

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The following commit has been merged into the core/rcu branch of tip:

Commit-ID: b3e627d3d5092a87fc9b9e37e341610cfecfbfdc
Gitweb: https://git.kernel.org/tip/b3e627d3d5092a87fc9b9e37e341610cfecfbfdc
Author: Lai Jiangshan <laijs@xxxxxxxxxxxxxxxxx>
AuthorDate: Tue, 15 Oct 2019 02:55:57
Committer: Paul E. McKenney <paulmck@xxxxxxxxxx>
CommitterDate: Mon, 09 Dec 2019 12:37:51 -08:00

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@xxxxxxxxxxxxxxxxx>
Signed-off-by: Lai Jiangshan <jiangshanlai@xxxxxxxxx>
Reviewed-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
include/linux/rcupdate.h | 4 ++--
include/trace/events/rcu.h | 4 ++--
kernel/rcu/Kconfig | 13 +++++++------
kernel/rcu/Makefile | 1 -
kernel/rcu/rcu.h | 2 +-
kernel/rcu/update.c | 2 +-
kernel/sysctl.c | 2 +-
7 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 0b75063..70a41cd 100644
--- 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
--- 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
--- 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
--- 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
--- 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
--- 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
--- 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,

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