Hi Thomas,
Thank you for the review.
On 21/08/2019 15:02, Thomas Gleixner wrote:
On Wed, 21 Aug 2019, Julien Grall wrote:
migration_base is used as a placeholder when an hrtimer is switching
between base (see switch_hrtimer_timer_base). It is possible
theoritically possible to have timer->base equal to migration_base.
Even if it is a placeholder, it would pass all the current check in
hrtimer_grab_expiry_lock() leading to use softirq_expiry_lock
uninitialized.
This is can be prevented by checking whether the base is equal to
the placeholder (i.e. migration_base).
That's a lame argument. The point is that it does not make sense to do that
on migration base, but not for the reason you are giving (uninitialized
lock).
Fair point, I will update the commit message.
If base == migration_base then there is no point to lock soft_expiry_lock
simply because the timer is not executing the callback in soft irq context
and the whole lock/unlock dance can be avoided.
But, yes. Good catch.
Do you want me to resend the series or can I just provide an update to the
commit message here?
Cheers,
--
Julien Grall
