Messages in this thread | | | Date | Wed, 20 Oct 2010 21:39:53 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH 1/2 v2] rcu,cleanup: move synchronize_sched_expedited() out of sched.c |
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On Thu, Oct 21, 2010 at 11:29:05AM +0800, Lai Jiangshan wrote: > On 10/21/2010 08:19 AM, Paul E. McKenney wrote: > > On Wed, Oct 20, 2010 at 12:15:12PM -0700, Paul E. McKenney wrote: > >> On Wed, Oct 20, 2010 at 02:12:58PM +0800, Lai Jiangshan wrote: > >>> The first version of synchronize_sched_expedited() use the migration code > >>> of the scheduler code, so it have to be implemented in sched.c > >>> > >>> but now, the synchronize_sched_expedited() does not use such code, > >>> it is time to move it out of sched.c. > >>> > >>> Different rcu implementation' synchronize_sched_expedited() are also > >>> different. so we move synchronize_sched_expedited() to kernel/rcutree_plugin.h > >>> or include/linux/rcutiny.h instead of kerenl/rcupdate.c > >> > >> Queued, thank you!!! > > > > Hello again, Lai, > > > > I hit the following build error during testing: > > > > kernel/built-in.o: In function `.synchronize_rcu_expedited': > > (.text+0x787d8): undefined reference to `.synchronize_sched_expedited' > > kernel/built-in.o:(.toc1+0x1fe0): undefined reference to `synchronize_sched_expedited' > > > > This build uses defconfig with the following applied: > > > > CONFIG_RCU_TRACE=y > > CONFIG_RCU_FAST_NO_HZ=y > > CONFIG_NO_HZ=y > > CONFIG_RCU_CPU_STALL_DETECTOR=y > > CONFIG_SMP=y > > CONFIG_RCU_FANOUT=8 > > CONFIG_NR_CPUS=8 > > CONFIG_RCU_FANOUT_EXACT=n > > CONFIG_HOTPLUG_CPU=y > > CONFIG_PREEMPT_NONE=y > > CONFIG_PREEMPT_VOLUNTARY=n > > CONFIG_PREEMPT=n > > CONFIG_TREE_RCU=y > > CONFIG_TREE_PREEMPT_RCU=n > > CONFIG_RCU_TORTURE_TEST=m > > CONFIG_MODULE_UNLOAD=y > > CONFIG_SYSFS_DEPRECATED_V2=y > > CONFIG_IKCONFIG=y > > CONFIG_IKCONFIG_PROC=y > > > > Thoughts? > > > > Thanx, Paul > > > > > > I moved the code into CONFIG_TREE_PREEMPT_RCU=y codes. fixed version:
Thank you, queued and am retesting.
Thanx, Paul
> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> > --- > diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h > index 0d0b640..ead36da 100644 > --- a/include/linux/rcupdate.h > +++ b/include/linux/rcupdate.h > @@ -66,7 +66,6 @@ extern void call_rcu_sched(struct rcu_head *head, > extern void synchronize_sched(void); > extern void rcu_barrier_bh(void); > extern void rcu_barrier_sched(void); > -extern void synchronize_sched_expedited(void); > extern int sched_expedited_torture_stats(char *page); > > static inline void __rcu_read_lock_bh(void) > diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h > index 13877cb..4d84452 100644 > --- a/include/linux/rcutiny.h > +++ b/include/linux/rcutiny.h > @@ -58,6 +58,11 @@ static inline void synchronize_rcu_bh_expedited(void) > synchronize_sched(); > } > > +static inline void synchronize_sched_expedited(void) > +{ > + synchronize_sched(); > +} > + > #ifdef CONFIG_TINY_RCU > > static inline void rcu_preempt_note_context_switch(void) > diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h > index 95518e6..9a1fd6c 100644 > --- a/include/linux/rcutree.h > +++ b/include/linux/rcutree.h > @@ -47,6 +47,7 @@ static inline void exit_rcu(void) > #endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */ > > extern void synchronize_rcu_bh(void); > +extern void synchronize_sched_expedited(void); > extern void synchronize_rcu_expedited(void); > > static inline void synchronize_rcu_bh_expedited(void) > diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h > index 0e75d60..0de359b 100644 > --- a/kernel/rcutree_plugin.h > +++ b/kernel/rcutree_plugin.h > @@ -25,6 +25,7 @@ > */ > > #include <linux/delay.h> > +#include <linux/stop_machine.h> > > /* > * Check the RCU kernel configuration parameters and print informative > @@ -1014,6 +1015,76 @@ static void __init __rcu_init_preempt(void) > > #endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */ > > +#ifndef CONFIG_SMP > + > +void synchronize_sched_expedited(void) > +{ > + cond_resched(); > +} > +EXPORT_SYMBOL_GPL(synchronize_sched_expedited); > + > +#else /* #ifndef CONFIG_SMP */ > + > +static atomic_t synchronize_sched_expedited_count = ATOMIC_INIT(0); > + > +static int synchronize_sched_expedited_cpu_stop(void *data) > +{ > + /* > + * There must be a full memory barrier on each affected CPU > + * between the time that try_stop_cpus() is called and the > + * time that it returns. > + * > + * In the current initial implementation of cpu_stop, the > + * above condition is already met when the control reaches > + * this point and the following smp_mb() is not strictly > + * necessary. Do smp_mb() anyway for documentation and > + * robustness against future implementation changes. > + */ > + smp_mb(); /* See above comment block. */ > + return 0; > +} > + > +/* > + * Wait for an rcu-sched grace period to elapse, but use "big hammer" > + * approach to force grace period to end quickly. This consumes > + * significant time on all CPUs, and is thus not recommended for > + * any sort of common-case code. > + * > + * Note that it is illegal to call this function while holding any > + * lock that is acquired by a CPU-hotplug notifier. Failing to > + * observe this restriction will result in deadlock. > + */ > +void synchronize_sched_expedited(void) > +{ > + int snap, trycount = 0; > + > + smp_mb(); /* ensure prior mod happens before capturing snap. */ > + snap = atomic_read(&synchronize_sched_expedited_count) + 1; > + get_online_cpus(); > + while (try_stop_cpus(cpu_online_mask, > + synchronize_sched_expedited_cpu_stop, > + NULL) == -EAGAIN) { > + put_online_cpus(); > + if (trycount++ < 10) > + udelay(trycount * num_online_cpus()); > + else { > + synchronize_sched(); > + return; > + } > + if (atomic_read(&synchronize_sched_expedited_count) - snap > 0) { > + smp_mb(); /* ensure test happens before caller kfree */ > + return; > + } > + get_online_cpus(); > + } > + atomic_inc(&synchronize_sched_expedited_count); > + smp_mb__after_atomic_inc(); /* ensure post-GP actions seen after GP. */ > + put_online_cpus(); > +} > +EXPORT_SYMBOL_GPL(synchronize_sched_expedited); > + > +#endif /* #else #ifndef CONFIG_SMP */ > + > #if !defined(CONFIG_RCU_FAST_NO_HZ) > > /* > diff --git a/kernel/sched.c b/kernel/sched.c > index abf8440..9dc7775 100644 > --- a/kernel/sched.c > +++ b/kernel/sched.c > @@ -9332,72 +9332,3 @@ struct cgroup_subsys cpuacct_subsys = { > }; > #endif /* CONFIG_CGROUP_CPUACCT */ > > -#ifndef CONFIG_SMP > - > -void synchronize_sched_expedited(void) > -{ > - barrier(); > -} > -EXPORT_SYMBOL_GPL(synchronize_sched_expedited); > - > -#else /* #ifndef CONFIG_SMP */ > - > -static atomic_t synchronize_sched_expedited_count = ATOMIC_INIT(0); > - > -static int synchronize_sched_expedited_cpu_stop(void *data) > -{ > - /* > - * There must be a full memory barrier on each affected CPU > - * between the time that try_stop_cpus() is called and the > - * time that it returns. > - * > - * In the current initial implementation of cpu_stop, the > - * above condition is already met when the control reaches > - * this point and the following smp_mb() is not strictly > - * necessary. Do smp_mb() anyway for documentation and > - * robustness against future implementation changes. > - */ > - smp_mb(); /* See above comment block. */ > - return 0; > -} > - > -/* > - * Wait for an rcu-sched grace period to elapse, but use "big hammer" > - * approach to force grace period to end quickly. This consumes > - * significant time on all CPUs, and is thus not recommended for > - * any sort of common-case code. > - * > - * Note that it is illegal to call this function while holding any > - * lock that is acquired by a CPU-hotplug notifier. Failing to > - * observe this restriction will result in deadlock. > - */ > -void synchronize_sched_expedited(void) > -{ > - int snap, trycount = 0; > - > - smp_mb(); /* ensure prior mod happens before capturing snap. */ > - snap = atomic_read(&synchronize_sched_expedited_count) + 1; > - get_online_cpus(); > - while (try_stop_cpus(cpu_online_mask, > - synchronize_sched_expedited_cpu_stop, > - NULL) == -EAGAIN) { > - put_online_cpus(); > - if (trycount++ < 10) > - udelay(trycount * num_online_cpus()); > - else { > - synchronize_sched(); > - return; > - } > - if (atomic_read(&synchronize_sched_expedited_count) - snap > 0) { > - smp_mb(); /* ensure test happens before caller kfree */ > - return; > - } > - get_online_cpus(); > - } > - atomic_inc(&synchronize_sched_expedited_count); > - smp_mb__after_atomic_inc(); /* ensure post-GP actions seen after GP. */ > - put_online_cpus(); > -} > -EXPORT_SYMBOL_GPL(synchronize_sched_expedited); > - > -#endif /* #else #ifndef CONFIG_SMP */ > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
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