On Wed, 26 Feb 2025, Alexei Starovoitov wrote:
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/
Yes, that is fine.
Thanks,
Davidlohr
