[PATCH RFC 0/9] Fix data races on hrtimer_sleeper ->task field

[Paul E. McKenney]

Hello!

In CONFIG_KCSAN_STRICT=y mode, KCSAN finds data races on the
hrtimer_sleeper structure's ->task field.  This field is used to indicate
owner of this structure, and also to signal the sleeper that the sleep
is over through use of a store of NULL.

Because access to the ->task field is open-coded across several kernel
subsystems, this series creates accessor functions creatively named
hrtimer_sleeper_task_get() and hrtimer_sleeper_task_set(), and uses
these throughout.

A key goal of this and similar serieses is to reduce KCSAN noise in
strict mode so that new data races are more visible.

The series is as follows:

1.	hrtimer: Mark data-racy accesses to hrtimer_sleeper ->task field.

2.	aio: Use accessor for hrtimer_sleeper ->task field.

3.	wait: Use accessor for hrtimer_sleeper ->task field.

4.	io-uring: Use accessor for hrtimer_sleeper ->task field.

5.	futex: Use accessor for hrtimer_sleeper ->task field in waitwake.c.

6.	timers: Use accessor for hrtimer_sleeper ->task field in
	sleep_timeout.c.

7.	net: pktgen: Use accessor for hrtimer_sleeper ->task field.

8.	rtmutex: Use accessor for hrtimer_sleeper ->task field.

9.	futex: Use accessor for hrtimer_sleeper ->task field in requeue.

						Thanx, Paul

------------------------------------------------------------------------

 fs/aio.c                    |    2 +-
 include/linux/hrtimer.h     |    8 ++++++++
 include/linux/wait.h        |    2 +-
 io_uring/rw.c               |    2 +-
 kernel/futex/requeue.c      |    2 +-
 kernel/futex/waitwake.c     |    8 ++++----
 kernel/locking/rtmutex.c    |    2 +-
 kernel/time/hrtimer.c       |   14 +++++++-------
 kernel/time/sleep_timeout.c |    4 ++--
 net/core/pktgen.c           |    4 ++--
 10 files changed, 28 insertions(+), 20 deletions(-)