tree a129934628bb794f4874de18976f21a4914e4be3
parent 606aae0c5b8d58d0e7cb0fd883b7dd67bf984e6e
author Paul E. McKenney <paulmck@kernel.org> 1655397037 -0700
committer Paul E. McKenney <paulmck@kernel.org> 1655401653 -0700

context_tracking: Use arch_atomic_read() in __ct_state for KASAN

Context tracking's __ct_state() function can be invoked from noinstr state
where RCU is not watching.  This means that its use of atomic_read()
causes KASAN to invoke the non-noinstr __kasan_check_read() function
from the noinstr function __ct_state().  This is problematic because
someone tracing the __kasan_check_read() function could get a nasty
surprise because of RCU not watching.

This commit therefore replaces the __ct_state() function's use of
atomic_read() with arch_atomic_read(), which KASAN does not attempt to
add instrumention to.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Marco Elver <elver@google.com>
Reviewed-by: Marco Elver <elver@google.com>