Re: [PATCH RT v2 0/3] riscv: add PREEMPT_RT support

Jisheng Zhang
2023-11-01T11:54:26Z

On Tue, Oct 31, 2023 at 05:44:11PM +0100, Sebastian Andrzej Siewior wrote:
> On 2023-10-31 23:49:29 [+0800], Jisheng Zhang wrote:
> > Yes there's no third patch. I didn't use the correct number in patch0's
> > subject.
>
> So it looks fine. The warning was CPU-hotplug related
> https://lore.kernel.org/all/0abd0acf-70a1-d546-a517-19efe60042d1@microchip.com/
>
> and it looks to be gone as of commit
> 5944ce092b97c ("arch_topology: Build cacheinfo from primary CPU")
>
> so that good. Any double checking is welcome of course ;)
> JUMP_LABELs don't use stop_cpu. Check.
> The timer is PERCPU. Check.
> Can't find perf events. But the commit for threaded interrupts claims to
> have them per-CPU.
> Has HAVE_POSIX_CPU_TIMERS_TASK_WORK with generic kvm. Check.
>
> die() and die_lock. It looks like die_lock is acquired when the system
> is done and requires medical assistance. This would qualify it for a
> raw_spinlock_t. Also, should any of the bad things happen in a section
> with disabled preemption or interrupts then a spinlock_t can not be
> acquired. Unless die() is always invoked in a preemptible context…
>
> The other things are covered by the generic code. I think I didn't miss
> anything…
> I going to have new release by the end of the week at the latest with
> this bits. Please look after the die_lock.

Thank you so much, I will check.

Hi @Conor,

If you help to try this series, can you please apply Evan' misaligned
access probe probe patch? Refer to [1] for details. NOTE: this is not
related with RT patches because I can reproduce the bug with v6.6.

Link: https://lore.kernel.org/linux-riscv/ZUI3JKff9SgsA3Z%2F@xhacker/ [1]
>
> Sebastian