From: Mark Rutland <mark.rutland@arm.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org, benh@kernel.crashing.org,
boqun.feng@gmail.com, bp@alien8.de, catalin.marinas@arm.com,
dvyukov@google.com, elver@google.com, ink@jurassic.park.msu.ru,
jonas@southpole.se, juri.lelli@redhat.com, linux@armlinux.org.uk,
luto@kernel.org, mattst88@gmail.com, mingo@redhat.com,
monstr@monstr.eu, mpe@ellerman.id.au, paulmck@kernel.org,
paulus@samba.org, peterz@infradead.org, rth@twiddle.net,
shorne@gmail.com, stefan.kristiansson@saunalahti.fi,
vincent.guittot@linaro.org, will@kernel.org
Subject: Re: [RFC PATCH 01/10] thread_info: add helpers to snapshot thread flags
Date: Mon, 21 Jun 2021 09:29:51 +0100 [thread overview]
Message-ID: <20210621082951.GC37068@C02TD0UTHF1T.local> (raw)
In-Reply-To: <87h7hth4ln.ffs@nanos.tec.linutronix.de>
On Sun, Jun 20, 2021 at 12:28:04AM +0200, Thomas Gleixner wrote:
> On Wed, Jun 09 2021 at 13:19, Mark Rutland wrote:
> > We have common helpers to manipulate individual thread flags, but where
> > code wants to check several flags at once, it must open code reading
> > current_thread_info()->flags and operating on a snapshot.
>
> Who's we?
Locally I've changed that to:
| In <linux/thread_info.h> there are helpers to [...]
Please shout if there's a better way of wording that!
> > As some flags can be set remotely it's necessary to use READ_ONCE() to
> > get a consistent snapshot even when IRQs are disabled, but some code
> > forgets to do this. Generally this is unlike to cause a problem in
> > practice, but it is somewhat unsound, and KCSAN will legitimately warn
> > that there is a data race.
> >
> > To make it easier to do the right thing, and to highlight that
> > concurrent modification is possible, let's add a new helpers to
> > snapshot
>
> let's add? Why not simply "add"?
Done.
> > +static inline unsigned long read_ti_thread_flags(struct thread_info *ti)
>
> __always_inline() as Marco pointed out already
>
> Other than those nitpicks:
>
> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Thanks!
Mark.
next prev parent reply other threads:[~2021-06-21 8:30 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-09 12:19 [RFC PATCH 00/10] thread_info: use helpers to snapshot thread flags Mark Rutland
2021-06-09 12:19 ` [RFC PATCH 01/10] thread_info: add " Mark Rutland
2021-06-10 9:01 ` Marco Elver
2021-06-11 9:17 ` Mark Rutland
2021-06-19 22:28 ` Thomas Gleixner
2021-06-21 8:29 ` Mark Rutland [this message]
2021-06-09 12:19 ` [RFC PATCH 02/10] entry: " Mark Rutland
2021-06-09 12:19 ` [RFC PATCH 03/10] sched: " Mark Rutland
2021-06-09 12:19 ` [RFC PATCH 04/10] alpha: " Mark Rutland
2021-06-09 12:19 ` [RFC PATCH 05/10] arm: " Mark Rutland
2021-06-09 12:19 ` [RFC PATCH 06/10] arm64: read " Mark Rutland
2021-06-16 22:07 ` kernel test robot
2021-06-09 12:19 ` [RFC PATCH 07/10] microblaze: snapshot " Mark Rutland
2021-06-09 12:19 ` [RFC PATCH 08/10] openrisc: " Mark Rutland
2021-06-10 19:14 ` Stafford Horne
2021-06-09 12:20 ` [RFC PATCH 09/10] powerpc: " Mark Rutland
2021-06-15 13:18 ` Michael Ellerman
2021-06-21 8:46 ` Mark Rutland
2021-06-09 12:20 ` [RFC PATCH 10/10] x86: " Mark Rutland
2021-06-19 22:30 ` Thomas Gleixner
2021-06-21 8:35 ` Mark Rutland
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