linux-kernel - Re: [PATCH 3/3] arm64: ftrace: add cond_resched() to func ftrace_make

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Message-ID: <20181204132344.2fcf13c3@vmware.local.home>
Date:   Tue, 4 Dec 2018 13:23:44 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Anders Roxell <anders.roxell@...aro.org>
Cc:     Will Deacon <will.deacon@....com>, Arnd Bergmann <arnd@...db.de>,
        mingo@...hat.com, Catalin Marinas <catalin.marinas@....com>,
        Kees Cook <keescook@...omium.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 3/3] arm64: ftrace: add cond_resched() to func
 ftrace_make_(call|nop)

On Tue, 4 Dec 2018 19:07:16 +0100
Anders Roxell <anders.roxell@...aro.org> wrote:


> > > > +   schedulable = !irqs_disabled() & !preempt_count();  
> > >
> > > Looks suspiciously like a bitwise preemptible() to me!  
> >
> > Ah, thanks. Yeah, that should have been &&. But what did you expect.
> > I didn't even compile this ;-)
> >  


> > If it does, then I'll add it. Or take a patch for it ;-)  
> 
> I tested your patch. it worked.
> 
> I'll send a patch shortly.
>

Thanks. Please add a comment above the schedulable test stating that
some archs call this with interrupts or preemption disabled, but
other archs don't and this can cause a tremendous unneeded latency.

-- Steve