Re: [PATCH] rcu: make PREEMPT_RCU to be a decoration of TREE_RCU
From: Lai Jiangshan
Date: Mon Oct 14 2019 - 22:46:00 EST
On 2019/10/15 10:00 äå, Paul E. McKenney wrote:
On Tue, Oct 15, 2019 at 09:50:21AM +0800, Lai Jiangshan wrote:
On Tue, Oct 15, 2019 at 9:46 AM Paul E. McKenney <paulmck@xxxxxxxxxx> wrote:
On Mon, Oct 14, 2019 at 02:48:32PM -0400, Joel Fernandes wrote:
On Sun, Oct 13, 2019 at 12:59:57PM +0000, Lai Jiangshan wrote:
Currently PREEMPT_RCU and TREE_RCU are "contrary" configs
when they can't be both on. But PREEMPT_RCU is actually a kind
of TREE_RCU in the implementation. It seams to be appropriate
to make PREEMPT_RCU to be a decorative option of TREE_RCU.
Looks like a nice simplification and so far I could not poke any holes in the
code...
I am in support of this patch for further review and testing. Thanks!
Reviewed-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
Thank you both!
Lai, what is this patch against? It does not want to apply to the current
-rcu "dev" branch.
Oh, sorry
I wrongly made the change base on upstream.
I will rebase later.
Very good, looking forward to this updated version.
Thanx, Paul
In my box, the patch can be applied to the -rcu "dev" well.
And there is nothing strange after boot.
Have I just made a mistake a again? In my box, the HEAD
of -rcu "dev" is 9725023b ("torture: Handle jitter for CPUs that cannot
be offlined")
Thanks
Lai
thanks
Lai
Thanx, Paul
thanks,
- Joel
Signed-off-by: Lai Jiangshan <jiangshanlai@xxxxxxxxx>
Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxxxxx>
---
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 75a2eded7aa2..1eee9f6c27f9 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>
@@ -583,7 +583,7 @@ 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 694bd040cf51..1ce15c5be4c8 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
@@ -425,7 +425,7 @@ 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 7644eda17d62..0303934e6ef0 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 020e8b6a644b..82d5fba48b2f 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 8fd4f82c9b3d..4149ba76824f 100644
--- a/kernel/rcu/rcu.h
+++ b/kernel/rcu/rcu.h
@@ -452,7 +452,7 @@ 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 rcutorture_record_progress(unsigned long vernum);
diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 1861103662db..34a7452b25fd 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 00fcea236eba..2ace158a4d72 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,
--
2.20.1