Messages in this thread | | | Date | Wed, 16 Nov 2011 11:54:36 -0800 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH tip/core/rcu 4/9] sched: add is_idle_task() to handle invalidated uses of idle_cpu() |
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On Tue, Nov 15, 2011 at 01:13:02PM -0800, Josh Triplett wrote: > On Tue, Nov 15, 2011 at 12:28:00PM -0800, Paul E. McKenney wrote: > > From: Paul E. McKenney <paul.mckenney@linaro.org> > > > > Commit 908a3283 (Fix idle_cpu()) invalidated some uses of idle_cpu(), > > which used to say whether or not the CPU was running the idle task, > > but now instead says whether or not the CPU is running the idle task > > in the absence of pending wakeups. Although this new implementation > > gives a better answer to the question "is this CPU idle?", it also > > invalidates other uses that were made of idle_cpu(). > > > > This commit therefore introduces a new is_idle_task() API member > > that determines whether or not the specified task is one of the > > idle tasks, allowing open-coded "->pid == 0" sequences to be replaced > > by something more meaningful. > > > > Suggested-by: Josh Triplett <josh@joshtriplett.org> > > Suggested-by: Peter Zijlstra <peterz@infradead.org> > > Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> > > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > > --- > > include/linux/sched.h | 1 + > > kernel/sched.c | 9 +++++++++ > > 2 files changed, 10 insertions(+), 0 deletions(-) > > > > diff --git a/include/linux/sched.h b/include/linux/sched.h > > index 68daf4f..4b1077b 100644 > > --- a/include/linux/sched.h > > +++ b/include/linux/sched.h > > @@ -2071,6 +2071,7 @@ extern int sched_setscheduler(struct task_struct *, int, > > extern int sched_setscheduler_nocheck(struct task_struct *, int, > > const struct sched_param *); > > extern struct task_struct *idle_task(int cpu); > > +extern int is_idle_task(struct task_struct *p); > > The kernel has a bool type; please use it here rather than int, to make > the return value more obvious. > > Also, any particular reason not to make this a static inline?
That does work for all the uses thus far, so made both suggested changes.
Thanx, Paul
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