Re: [PATCH v1] rcu: Fix and improve RCU read lock checks when !CONFIG_DEBUG_LOCK_ALLOC

[Gao Xiang]

On 2023/7/13 12:27, Paul E. McKenney wrote:
> On Thu, Jul 13, 2023 at 10:02:17AM +0800, Gao Xiang wrote:
> >

... sorry forget some.

> One additional question...  What is your plan for kernels built with
> CONFIG_PREEMPT_COUNT=n?  After all, in such kernels, there is no way
> that I know of for code to determine whether it is in an RCU read-side
> critical section, holding a spinlock, or running with preemption disabled.

I'm not sure if Android (or all targetted) users use or care about
this configuration (CONFIG_PREEMPT_COUNT=n), personally I think
for such configuration we could just fall back to the workqueue
approach all the time.

Anyway, such optimization really comes from real workloads /
experience, users don't live well without such mitigation.

Thanks,
Gao Xiang

> 						Thanx, Paul