On Wed, Feb 26, 2025 at 9:01 AM Davidlohr Bueso <dave@xxxxxxxxxxxx> wrote: > > On Fri, 14 Feb 2025, Vlastimil Babka wrote: > > >From: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> > > > >In !PREEMPT_RT local_lock_irqsave() disables interrupts to protect > >critical section, but it doesn't prevent NMI, so the fully reentrant > >code cannot use local_lock_irqsave() for exclusive access. > > > >Introduce localtry_lock_t and localtry_lock_irqsave() that > >disables interrupts and sets acquired=1, so localtry_lock_irqsave() > >from NMI attempting to acquire the same lock will return false. > > > >In PREEMPT_RT local_lock_irqsave() maps to preemptible spin_lock(). > >Map localtry_lock_irqsave() to preemptible spin_trylock(). > >When in hard IRQ or NMI return false right away, since > >spin_trylock() is not safe due to PI issues. > > > >Note there is no need to use local_inc for acquired variable, > >since it's a percpu variable with strict nesting scopes. > > > > LGTM. > > Acked-by: Davidlohr Bueso <dave@xxxxxxxxxxxx> Thanks for the review. Do you mind if I apply your ack to the latest version of this patch? https://lore.kernel.org/bpf/20250222024427.30294-2-alexei.starovoitov@xxxxxxxxx/
