| Message ID | 1346360743-3628-7-git-send-email-paulmck@linux.vnet.ibm.com |
|---|---|
| State | New |
| Headers | show |
On Thu, Aug 30, 2012 at 02:05:24PM -0700, Paul E. McKenney wrote: > From: Frederic Weisbecker <fweisbec@gmail.com> > > 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 <fweisbec@gmail.com> > Cc: Alessio Igor Bogani <abogani@kernel.org> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Avi Kivity <avi@redhat.com> > Cc: Chris Metcalf <cmetcalf@tilera.com> > Cc: Christoph Lameter <cl@linux.com> > Cc: Geoff Levand <geoff@infradead.org> > Cc: Gilad Ben Yossef <gilad@benyossef.com> > Cc: Hakan Akkan <hakanakkan@gmail.com> > Cc: H. Peter Anvin <hpa@zytor.com> > Cc: Ingo Molnar <mingo@kernel.org> > Cc: Josh Triplett <josh@joshtriplett.org> > Cc: Kevin Hilman <khilman@ti.com> > Cc: Max Krasnyansky <maxk@qualcomm.com> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Stephen Hemminger <shemminger@vyatta.com> > Cc: Steven Rostedt <rostedt@goodmis.org> > Cc: Sven-Thorsten Dietrich <thebigcorporation@gmail.com> > Cc: Thomas Gleixner <tglx@linutronix.de> > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> > 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 >
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();