Messages in this thread Patch in this message | | | Date | Wed, 4 Sep 2019 16:39:18 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [PATCH] hrtimer: Add a missing bracket and hide `migration_base' on !SMP |
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On Wed, 4 Sep 2019, Sebastian Andrzej Siewior wrote:
> Commit > 68b2c8c1e4210 ("hrtimer: Don't take expiry_lock when timer is currently migrated")
That is the same information as in the fixes tag. So you can say something like this:
The recent change to avoid taking the expiry lock when a timer is currently migrated missed .....
> missed to add a bracket at the end of the if statement leading to > compile errors. > Since that commit the variable `migration_base' is always used but only > available on SMP configuration thus leading to another compile error. > The changelog says > "The timer base and base->cpu_base cannot be NULL in the code path" > > so it is safe to limit this check to SMP configurations only. > > Add the missing bracket to the if statement and hide `migration_base' > behind CONFIG_SMP bars. > > Fixes: 68b2c8c1e4210 ("hrtimer: Don't take expiry_lock when timer is currently migrated") > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> > --- > kernel/time/hrtimer.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c > index f5a1a5e16216c..bc84c74ae5b96 100644 > --- a/kernel/time/hrtimer.c > +++ b/kernel/time/hrtimer.c > @@ -1216,12 +1216,16 @@ void hrtimer_cancel_wait_running(const struct hrtimer *timer) > { > /* Lockless read. Prevent the compiler from reloading it below */ > struct hrtimer_clock_base *base = READ_ONCE(timer->base); > + bool is_migration_base = false; > > /* > * Just relax if the timer expires in hard interrupt context or if > * it is currently on the migration base. > */ > - if (!timer->is_soft || base == &migration_base) > +#ifdef CONFIG_SMP > + is_migration_base = base == &migration_base; > +#endif
That's beyond ugly.
What's wrong with:
if (!timer->is_soft || is_migration_base(base))
and have two helpers in the relevant ifdeffed section?
Thanks,
tglx
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