From: Stafford Horne <shorne@gmail.com>
To: Mark Rutland <mark.rutland@arm.com>
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,
stefan.kristiansson@saunalahti.fi, tglx@linutronix.de,
vincent.guittot@linaro.org, will@kernel.org
Subject: Re: [RFC PATCH 08/10] openrisc: snapshot thread flags
Date: Fri, 11 Jun 2021 04:14:45 +0900 [thread overview]
Message-ID: <YMJkpaHyxCd/Wqke@antec> (raw)
In-Reply-To: <20210609122001.18277-9-mark.rutland@arm.com>
On Wed, Jun 09, 2021 at 01:19:59PM +0100, Mark Rutland wrote:
> Some thread flags can be set remotely, and so even when IRQs are
> disabled, the flags can change under our feet. Generally this is
> unlikely to cause a problem in practice, but it is somewhat unsound, and
> KCSAN will legitimately warn that there is a data race.
>
> To avoid such issues, we should snapshot the flags prior to using them.
> Let's use the new helpers to do so on openrisc.
>
> Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> Cc: Jonas Bonn <jonas@southpole.se>
> Cc: Stafford Horne <shorne@gmail.com>
> Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
> ---
> arch/openrisc/kernel/signal.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/openrisc/kernel/signal.c b/arch/openrisc/kernel/signal.c
> index 1ebcff271096..a730a914c2b4 100644
> --- a/arch/openrisc/kernel/signal.c
> +++ b/arch/openrisc/kernel/signal.c
> @@ -315,7 +315,7 @@ do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
> }
> }
> local_irq_disable();
> - thread_flags = current_thread_info()->flags;
> + thread_flags = read_thread_flags();
> } while (thread_flags & _TIF_WORK_MASK);
> return 0;
> }
This looks good to me. As per patch 01/10 this adds a READ_ONCE around the
original flags read.
Acked-by: Stafford Horne <shorne@gmail.com>
next prev parent reply other threads:[~2021-06-10 19:16 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
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 [this message]
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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