From: Mark Rutland <mark.rutland@arm.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Andi Kleen <ak@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Borislav Petkov <bp@suse.de>,
Catalin Marinas <catalin.marinas@arm.com>,
"David S. Miller" <davem@davemloft.net>,
Christoph Hellwig <hch@lst.de>,
kan.liang@intel.com, Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Rik van Riel <riel@surriel.com>, Will Deacon <will@kernel.org>
Subject: Re: [PATCH 1/9] sched/core: add is_kthread() helper
Date: Wed, 14 Aug 2019 12:32:32 +0100 [thread overview]
Message-ID: <20190814113232.GE17931@lakrids.cambridge.arm.com> (raw)
In-Reply-To: <CAMuHMdV_hZ-uMmKdqEutLL5+XkhhcKdSaurMUS2N46AhZwDNKQ@mail.gmail.com>
On Wed, Aug 14, 2019 at 01:26:43PM +0200, Geert Uytterhoeven wrote:
> Hi Mark,
>
> On Wed, Aug 14, 2019 at 12:43 PM Mark Rutland <mark.rutland@arm.com> wrote:
> > Code checking whether a task is a kthread isn't very consistent. Some
> > code correctly tests task->flags & PF_THREAD, while other code checks
> > task->mm (which can be true for a kthread which calls use_mm()).
> >
> > So that we can clean this up and keep the code easy to follow, let's add
> > an obvious helper function to test whether a task is a kthread.
> > Subsequent patches will use this as part of cleaning up and correcting
> > open-coded tests.
> >
> > At the same time, let's fix up the kerneldoc for is_idle_task() for
> > consistency with the new helper, using true/false rather than 0/1, given
> > the functions return bool.
> >
> > Signed-off-by: Mark Rutland <mark.rutland@arm.com>
>
> Thanks for your patch!
>
> > --- a/include/linux/sched.h
> > +++ b/include/linux/sched.h
> > @@ -1621,13 +1621,24 @@ extern struct task_struct *idle_task(int cpu);
> > * is_idle_task - is the specified task an idle task?
> > * @p: the task in question.
> > *
> > - * Return: 1 if @p is an idle task. 0 otherwise.
> > + * Return: true if @p is an idle task, false otherwise.
> > */
> > static inline bool is_idle_task(const struct task_struct *p)
> > {
> > return !!(p->flags & PF_IDLE);
> > }
> >
> > +/**
> > + * is_kthread - is the specified task a kthread
> > + * @p: the task in question.
> > + *
> > + * Return: true if @p is a kthread, false otherwise.
> > + */
> > +static inline bool is_kthread(const struct task_struct *p)
> > +{
> > + return !!(p->flags & PF_KTHREAD);
>
> The !! is not really needed.
> Probably you followed is_idle_task() above (where it's also not needed).
Indeed! I'm aware of the implicit bool conversion, but kept that for
consistency.
Peter, Ingo, do you have a preference?
Thanks,
Mark.
next prev parent reply other threads:[~2019-08-14 11:32 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-14 10:41 [PATCH 0/9] kthread detection cleanup Mark Rutland
2019-08-14 10:41 ` [PATCH 1/9] sched/core: add is_kthread() helper Mark Rutland
2019-08-14 11:26 ` Geert Uytterhoeven
2019-08-14 11:32 ` Mark Rutland [this message]
2019-08-19 8:52 ` Ingo Molnar
2019-08-21 11:21 ` Peter Zijlstra
2019-08-14 10:41 ` [PATCH 2/9] sched: treewide: use is_kthread() Mark Rutland
2019-08-14 11:27 ` Geert Uytterhoeven
2019-08-14 12:39 ` Sebastian Andrzej Siewior
2019-08-14 13:35 ` Mark Rutland
2019-08-14 13:37 ` Valentin Schneider
2019-08-14 10:41 ` [PATCH 3/9] kmemleak: correctly check for kthreads Mark Rutland
2019-08-14 16:39 ` Catalin Marinas
2019-08-14 10:41 ` [PATCH 4/9] arm/perf: " Mark Rutland
2019-08-14 10:41 ` [PATCH 5/9] arm64: correctly check for ktrheads Mark Rutland
2019-08-14 16:40 ` Catalin Marinas
2019-08-14 10:41 ` [PATCH 6/9] sparc/perf: correctly check for kthreads Mark Rutland
2019-08-14 16:26 ` David Miller
2019-08-14 10:41 ` [PATCH 7/9] x86/lbr: " Mark Rutland
2019-08-14 10:41 ` [PATCH 8/9] x86/fpu: " Mark Rutland
2019-08-14 13:07 ` Sebastian Andrzej Siewior
2019-08-14 13:39 ` Mark Rutland
2019-08-14 14:55 ` Sebastian Andrzej Siewior
2019-08-14 10:41 ` [PATCH 9/9] samples/kretprobe: " Mark Rutland
2019-08-14 13:43 ` [PATCH 0/9] kthread detection cleanup Valentin Schneider
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