linux-kernel - [tip: core/entry] alpha: Snapshot thread flags

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Date:   Tue, 30 Nov 2021 23:08:43 -0000
From:   "tip-bot2 for Mark Rutland" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Mark Rutland <mark.rutland@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Ivan Kokshaysky <ink@...assic.park.msu.ru>,
        Matt Turner <mattst88@...il.com>,
        Richard Henderson <rth@...ddle.net>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: core/entry] alpha: Snapshot thread flags

The following commit has been merged into the core/entry branch of tip:

Commit-ID:     7fb2b24bb5c5876a3205cb5b9a580f81e8c9f744
Gitweb:        https://git.kernel.org/tip/7fb2b24bb5c5876a3205cb5b9a580f81e8c9f744
Author:        Mark Rutland <mark.rutland@....com>
AuthorDate:    Mon, 29 Nov 2021 13:06:46 
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Wed, 01 Dec 2021 00:06:43 +01:00

alpha: Snapshot thread flags

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@....com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Acked-by: Paul E. McKenney <paulmck@...nel.org>
Cc: Ivan Kokshaysky <ink@...assic.park.msu.ru>
Cc: Matt Turner <mattst88@...il.com>
Cc: Richard Henderson <rth@...ddle.net>
Link: https://lore.kernel.org/r/20211129130653.2037928-5-mark.rutland@arm.com

---
 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 bc077ba..d8ed71d 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);
 }