[tip: core/entry] alpha: Snapshot thread flags

["tip-bot2 for Mark Rutland" <tip-bot2@linutronix.de>]

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

Commit-ID:     b8cdd8873327b967fe088ffab84c1f9456ef1767
Gitweb:        https://git.kernel.org/tip/b8cdd8873327b967fe088ffab84c1f9456ef1767
Author:        Mark Rutland <mark.rutland@arm.com>
AuthorDate:    Wed, 17 Nov 2021 16:30:42 
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Fri, 26 Nov 2021 21:20:13 +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@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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>
Link: https://lore.kernel.org/r/20211117163050.53986-5-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);
 }