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Date:   Fri, 5 May 2023 10:29:16 -0400
From:   Steven Rostedt <rostedt@goodmis.org>
To:     Peter Zijlstra <peterz@infradead.org>
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        Oleg Nesterov <oleg@redhat.com>,
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Subject: Re: [PATCH v7 2/3] sched/task: Add the
 put_task_struct_atomic_safe() function
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On Fri, 5 May 2023 10:26:02 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> > > IIRC, the in_task() is there because preemptible() doesn't check if it
> > > is running in interrupt context.    
> > 
> > #define preemptible()   (preempt_count() == 0 && !irqs_disabled())
> > 
> > When in interrupt context preempt_count() will have a non-zero value in
> > HARDIRQ_MASK and IRQs must be disabled, so preemptible() evaluates to
> > (false && false), last time I checked that ends up being false.  
> 
> Interesting, I can't find v5 anywhere in my mail folders (but I have
> v4 and v6!). Anyway, from just the context of this email, and seeing
> IS_ENABLED(CONFIG_PREEMPT_RT), I'm guessing that in_task() returns false if
> it's running in a interrupt thread, where preemtible() does not.

But then I question, does it matter if it is running in an interrupt thread
or not for put_task_struct()?

-- Steve