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From: Mark Rutland <mark.rutland@arm.com>
To: linux-kernel@vger.kernel.org
Cc: benh@kernel.crashing.org, boqun.feng@gmail.com, bp@alien8.de,
	catalin.marinas@arm.com, dvyukov@google.com, efuller@redhat.com,
	elver@google.com, ink@jurassic.park.msu.ru, jonas@southpole.se,
	juri.lelli@redhat.com, linux@armlinux.org.uk, luto@kernel.org,
	mark.rutland@arm.com, mattst88@gmail.com,
	michal.simek@xilinx.com, mingo@redhat.com, mpe@ellerman.id.au,
	npiggin@gmail.com, paulmck@kernel.org, paulus@samba.org,
	peterz@infradead.org, rth@twiddle.net, shorne@gmail.com,
	stefan.kristiansson@saunalahti.fi, tglx@linutronix.de,
	vincent.guittot@linaro.org, will@kernel.org
Subject: [PATCH v8 04/11] alpha: snapshot thread flags
Date: Mon, 29 Nov 2021 13:06:46 +0000	[thread overview]
Message-ID: <20211129130653.2037928-5-mark.rutland@arm.com> (raw)
In-Reply-To: <20211129130653.2037928-1-mark.rutland@arm.com>

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, a snapshot of the flags has to be taken prior to
using them. Some places already use READ_ONCE() for that, others do not.

Convert them all to the new flag accessor helpers.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Richard Henderson <rth@twiddle.net>
---
 arch/alpha/kernel/signal.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/alpha/kernel/signal.c b/arch/alpha/kernel/signal.c
index bc077babafab..d8ed71d5bed3 100644
--- a/arch/alpha/kernel/signal.c
+++ b/arch/alpha/kernel/signal.c
@@ -535,6 +535,6 @@ do_work_pending(struct pt_regs *regs, unsigned long thread_flags,
 			}
 		}
 		local_irq_disable();
-		thread_flags = current_thread_info()->flags;
+		thread_flags = read_thread_flags();
 	} while (thread_flags & _TIF_WORK_MASK);
 }
-- 
2.30.2


  parent reply	other threads:[~2021-11-29 13:09 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-29 13:06 [PATCH v8 00/11] thread_info: use helpers to snapshot thread flags Mark Rutland
2021-11-29 13:06 ` [PATCH v8 01/11] thread_info: add " Mark Rutland
2021-11-30 23:08   ` [tip: core/entry] thread_info: Add " tip-bot2 for Mark Rutland
2021-11-29 13:06 ` [PATCH v8 02/11] entry: " Mark Rutland
2021-11-30 23:08   ` [tip: core/entry] entry: Snapshot " tip-bot2 for Mark Rutland
2021-11-29 13:06 ` [PATCH v8 03/11] sched: snapshot " Mark Rutland
2021-11-30 23:08   ` [tip: core/entry] sched: Snapshot " tip-bot2 for Mark Rutland
2021-11-29 13:06 ` Mark Rutland [this message]
2021-11-30 23:08   ` [tip: core/entry] alpha: " tip-bot2 for Mark Rutland
2021-11-29 13:06 ` [PATCH v8 05/11] arm: snapshot " Mark Rutland
2021-11-30 23:08   ` [tip: core/entry] ARM: Snapshot " tip-bot2 for Mark Rutland
2021-11-29 13:06 ` [PATCH v8 06/11] arm64: snapshot " Mark Rutland
2021-11-30 23:08   ` [tip: core/entry] arm64: Snapshot " tip-bot2 for Mark Rutland
2021-11-29 13:06 ` [PATCH v8 07/11] microblaze: snapshot " Mark Rutland
2021-11-30 23:08   ` [tip: core/entry] microblaze: Snapshot " tip-bot2 for Mark Rutland
2021-11-29 13:06 ` [PATCH v8 08/11] openrisc: snapshot " Mark Rutland
2021-11-30 23:08   ` [tip: core/entry] openrisc: Snapshot " tip-bot2 for Mark Rutland
2021-11-29 13:06 ` [PATCH v8 09/11] powerpc: avoid discarding flags in system_call_exception() Mark Rutland
2021-11-30 23:08   ` [tip: core/entry] powerpc: Avoid " tip-bot2 for Mark Rutland
2021-11-29 13:06 ` [PATCH v8 10/11] powerpc: snapshot thread flags Mark Rutland
2021-11-30 23:08   ` [tip: core/entry] powerpc: Snapshot " tip-bot2 for Mark Rutland
2021-11-29 13:06 ` [PATCH v8 11/11] x86: snapshot " Mark Rutland
2021-11-30 23:08   ` [tip: core/entry] x86: Snapshot " tip-bot2 for Mark Rutland

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