kcsan: Add example to data_race() kerneldoc header

Although the data_race() kerneldoc header accurately states what it does,
some of the implications and usage patterns are non-obvious.  Therefore,
add a brief locking example and also state how to have KCSAN ignore
accesses while also preventing the compiler from folding, spindling,
or otherwise mutilating the access.

[ paulmck: Apply Bart Van Assche feedback. ]
[ paulmck: Apply feedback from Marco Elver. ]

Reported-by: Bart Van Assche <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>
Cc: Marco Elver <[email protected]>
Cc: Breno Leitao <[email protected]>
Cc: Jens Axboe <[email protected]>

0 files changed, 0 insertions, 0 deletions