Commit c924bf5a authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu: Clarify rcu_is_watching() kernel-doc comment 



Make it clear that this function always returns either true or false
without other planned failure modes.

Reported-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Reviewed-by: default avatarJoel Fernandes (Google) <joel@joelfernandes.org>
parent 6716f4d3

kernel/rcu/tree.c

+9 −5
Original line number Diff line number Diff line
@@ -677,12 +677,16 @@ static void rcu_disable_urgency_upon_qs(struct rcu_data *rdp) 
}



/**

 * rcu_is_watching - see if RCU thinks that the current CPU is not idle

 * rcu_is_watching - RCU read-side critical sections permitted on current CPU?

 *

 * Return true if RCU is watching the running CPU, which means that this

 * CPU can safely enter RCU read-side critical sections.  In other words,

 * if the current CPU is not in its idle loop or is in an interrupt or

 * NMI handler, return true.

 * Return @true if RCU is watching the running CPU and @false otherwise.

 * An @true return means that this CPU can safely enter RCU read-side

 * critical sections.

 *

 * Although calls to rcu_is_watching() from most parts of the kernel

 * will return @true, there are important exceptions.  For example, if the

 * current CPU is deep within its idle loop, in kernel entry/exit code,

 * or offline, rcu_is_watching() will return @false.

 *

 * Make notrace because it can be called by the internal functions of

 * ftrace, and making this notrace removes unnecessary recursion calls.