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 <[email protected]>
> ---
> 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
