On 2/13/25 04:35, Alexei Starovoitov 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. > > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> > Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx> I'm not the maintainer of this area, but with the fixes/addition I proposed, and having use for this lock variant myself, I think it's fair to add, fwiw: Acked-by: Vlastimil Babka <vbabka@xxxxxxx> Thanks.
