On Thu, Aug 30, 2012 at 02:05:24PM -0700, Paul E. McKenney wrote: > From: Frederic Weisbecker <[email protected]> > > Clear the syscalls hook of a task when it's scheduled out so that if > the task migrates, it doesn't run the syscall slow path on a CPU > that might not need it. > > Also set the syscalls hook on the next task if needed. > > Signed-off-by: Frederic Weisbecker <[email protected]> > Cc: Alessio Igor Bogani <[email protected]> > Cc: Andrew Morton <[email protected]> > Cc: Avi Kivity <[email protected]> > Cc: Chris Metcalf <[email protected]> > Cc: Christoph Lameter <[email protected]> > Cc: Geoff Levand <[email protected]> > Cc: Gilad Ben Yossef <[email protected]> > Cc: Hakan Akkan <[email protected]> > Cc: H. Peter Anvin <[email protected]> > Cc: Ingo Molnar <[email protected]> > Cc: Josh Triplett <[email protected]> > Cc: Kevin Hilman <[email protected]> > Cc: Max Krasnyansky <[email protected]> > Cc: Peter Zijlstra <[email protected]> > Cc: Stephen Hemminger <[email protected]> > Cc: Steven Rostedt <[email protected]> > Cc: Sven-Thorsten Dietrich <[email protected]> > Cc: Thomas Gleixner <[email protected]> > Signed-off-by: Paul E. McKenney <[email protected]>
Reviewed-by: Josh Triplett <[email protected]> > arch/um/drivers/mconsole_kern.c | 1 + > include/linux/rcupdate.h | 2 ++ > include/linux/sched.h | 8 ++++++++ > kernel/rcutree.c | 15 +++++++++++++++ > kernel/sched/core.c | 1 + > 5 files changed, 27 insertions(+), 0 deletions(-) > > diff --git a/arch/um/drivers/mconsole_kern.c b/arch/um/drivers/mconsole_kern.c > index 664a60e..c17de0d 100644 > --- a/arch/um/drivers/mconsole_kern.c > +++ b/arch/um/drivers/mconsole_kern.c > @@ -705,6 +705,7 @@ static void stack_proc(void *arg) > struct task_struct *from = current, *to = arg; > > to->thread.saved_task = from; > + rcu_switch(from, to); > switch_to(from, to, from); > } > > diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h > index e411117..1fc0a0e 100644 > --- a/include/linux/rcupdate.h > +++ b/include/linux/rcupdate.h > @@ -197,6 +197,8 @@ extern void rcu_user_enter(void); > extern void rcu_user_exit(void); > extern void rcu_user_enter_irq(void); > extern void rcu_user_exit_irq(void); > +extern void rcu_user_hooks_switch(struct task_struct *prev, > + struct task_struct *next); > #else > static inline void rcu_user_enter(void) { } > static inline void rcu_user_exit(void) { } > diff --git a/include/linux/sched.h b/include/linux/sched.h > index c147e70..e4d5936 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -1894,6 +1894,14 @@ static inline void rcu_copy_process(struct task_struct > *p) > > #endif > > +static inline void rcu_switch(struct task_struct *prev, > + struct task_struct *next) > +{ > +#ifdef CONFIG_RCU_USER_QS > + rcu_user_hooks_switch(prev, next); > +#endif > +} > + > static inline void tsk_restore_flags(struct task_struct *task, > unsigned long orig_flags, unsigned long flags) > { > diff --git a/kernel/rcutree.c b/kernel/rcutree.c > index e2fd370..af92681 100644 > --- a/kernel/rcutree.c > +++ b/kernel/rcutree.c > @@ -721,6 +721,21 @@ int rcu_is_cpu_idle(void) > } > EXPORT_SYMBOL(rcu_is_cpu_idle); > > +#ifdef CONFIG_RCU_USER_QS > +void rcu_user_hooks_switch(struct task_struct *prev, > + struct task_struct *next) > +{ > + struct rcu_dynticks *rdtp; > + > + /* Interrupts are disabled in context switch */ > + rdtp = &__get_cpu_var(rcu_dynticks); > + if (!rdtp->ignore_user_qs) { > + clear_tsk_thread_flag(prev, TIF_NOHZ); > + set_tsk_thread_flag(next, TIF_NOHZ); > + } > +} > +#endif /* #ifdef CONFIG_RCU_USER_QS */ > + > #if defined(CONFIG_PROVE_RCU) && defined(CONFIG_HOTPLUG_CPU) > > /* > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index d325c4b..07c6d9a 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -2081,6 +2081,7 @@ context_switch(struct rq *rq, struct task_struct *prev, > #endif > > /* Here we just switch the register state and the stack. */ > + rcu_switch(prev, next); > switch_to(prev, next, prev); > > barrier(); > -- > 1.7.8 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
