On Wed, May 13, 2015 at 02:37:52AM +0200, Frederic Weisbecker wrote:
> On Tue, May 12, 2015 at 03:30:45PM -0700, Paul E. McKenney wrote:
> > From: "Paul E. McKenney" <paul...@linux.vnet.ibm.com>
> >
> > Currently, Kconfig will ask the user whether RCU_USER_QS should be set.
> > This is silly because Kconfig already has all the information that it
> > needs to set this parameter. This commit therefore directly drives
> > the value of RCU_USER_QS via NO_HZ_FULL's "select" statement.
> >
> > Reported-by: Ingo Molnar <mi...@kernel.org>
> > Signed-off-by: Paul E. McKenney <paul...@linux.vnet.ibm.com>
> > Cc: Frederic Weisbecker <fweis...@gmail.com>
>
> ACK. And we should remove it completely and use NO_HZ_FULL instead.
> There won't seem to be more users.
Good point! I have queued the patch shown below for 4.3.
Thanx, Paul
------------------------------------------------------------------------
rcu: Drop RCU_USER_QS in favor of NO_HZ_FULL
The RCU_USER_QS Kconfig parameter is now just a synonym for NO_HZ_FULL,
so this commit eliminates RCU_USER_QS, replacing all uses with NO_HZ_FULL.
Reported-by: Frederic Weisbecker <fweis...@gmail.com>
Signed-off-by: Paul E. McKenney <paul...@linux.vnet.ibm.com>
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 03a899aabd17..18e377b92875 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -307,7 +307,7 @@ static inline void rcu_sysrq_end(void)
}
#endif /* #else #ifdef CONFIG_RCU_STALL_COMMON */
-#ifdef CONFIG_RCU_USER_QS
+#ifdef CONFIG_NO_HZ_FULL
void rcu_user_enter(void);
void rcu_user_exit(void);
#else
@@ -315,7 +315,7 @@ static inline void rcu_user_enter(void) { }
static inline void rcu_user_exit(void) { }
static inline void rcu_user_hooks_switch(struct task_struct *prev,
struct task_struct *next) { }
-#endif /* CONFIG_RCU_USER_QS */
+#endif /* CONFIG_NO_HZ_FULL */
#ifdef CONFIG_RCU_NOCB_CPU
void rcu_init_nohz(void);
diff --git a/init/Kconfig b/init/Kconfig
index 4c08197044f1..5b8726c10685 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -537,15 +537,6 @@ config RCU_STALL_COMMON
config CONTEXT_TRACKING
bool
-config RCU_USER_QS
- bool
- help
- This option sets hooks on kernel / userspace boundaries and
- puts RCU in extended quiescent state when the CPU runs in
- userspace. It means that when a CPU runs in userspace, it is
- excluded from the global RCU state machine and thus doesn't
- try to keep the timer tick on for RCU.
-
config CONTEXT_TRACKING_FORCE
bool "Force context tracking"
depends on CONTEXT_TRACKING
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 7651d7dd982c..012cbee9d354 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -696,7 +696,7 @@ void rcu_idle_enter(void)
}
EXPORT_SYMBOL_GPL(rcu_idle_enter);
-#ifdef CONFIG_RCU_USER_QS
+#ifdef CONFIG_NO_HZ_FULL
/**
* rcu_user_enter - inform RCU that we are resuming userspace.
*
@@ -709,7 +709,7 @@ void rcu_user_enter(void)
{
rcu_eqs_enter(1);
}
-#endif /* CONFIG_RCU_USER_QS */
+#endif /* CONFIG_NO_HZ_FULL */
/**
* rcu_irq_exit - inform RCU that current CPU is exiting irq towards idle
@@ -823,7 +823,7 @@ void rcu_idle_exit(void)
}
EXPORT_SYMBOL_GPL(rcu_idle_exit);
-#ifdef CONFIG_RCU_USER_QS
+#ifdef CONFIG_NO_HZ_FULL
/**
* rcu_user_exit - inform RCU that we are exiting userspace.
*
@@ -834,7 +834,7 @@ void rcu_user_exit(void)
{
rcu_eqs_exit(1);
}
-#endif /* CONFIG_RCU_USER_QS */
+#endif /* CONFIG_NO_HZ_FULL */
/**
* rcu_irq_enter - inform RCU that current CPU is entering irq away from idle
diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
index 579ce1b929af..4008d9f95dd7 100644
--- a/kernel/time/Kconfig
+++ b/kernel/time/Kconfig
@@ -92,12 +92,10 @@ config NO_HZ_FULL
depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
# We need at least one periodic CPU for timekeeping
depends on SMP
- # RCU_USER_QS dependency
depends on HAVE_CONTEXT_TRACKING
# VIRT_CPU_ACCOUNTING_GEN dependency
depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
select NO_HZ_COMMON
- select RCU_USER_QS
select RCU_NOCB_CPU
select VIRT_CPU_ACCOUNTING_GEN
select IRQ_WORK
--
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