Commit 366237e7 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

stop_machine: Provide RCU quiescent state in multi_cpu_stop() 



When multi_cpu_stop() loops waiting for other tasks, it can trigger an RCU
CPU stall warning.  This can be misleading because what is instead needed
is information on whatever task is blocking multi_cpu_stop().  This commit
therefore inserts an RCU quiescent state into the multi_cpu_stop()
function's waitloop.

Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent d38e6dc6

include/linux/rcutree.h

+1 −0
Original line number Diff line number Diff line
@@ -37,6 +37,7 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func); 


void rcu_barrier(void);

bool rcu_eqs_special_set(int cpu);

void rcu_momentary_dyntick_idle(void);

unsigned long get_state_synchronize_rcu(void);

void cond_synchronize_rcu(unsigned long oldstate);

kernel/rcu/tree.c

+1 −1
Original line number Diff line number Diff line
@@ -364,7 +364,7 @@ bool rcu_eqs_special_set(int cpu) 
 *

 * The caller must have disabled interrupts and must not be idle.

 */

static void __maybe_unused rcu_momentary_dyntick_idle(void)

void rcu_momentary_dyntick_idle(void)

{

	int special;

kernel/stop_machine.c

+1 −0
Original line number Diff line number Diff line
@@ -233,6 +233,7 @@ static int multi_cpu_stop(void *data) 
			 */

			touch_nmi_watchdog();

		}

		rcu_momentary_dyntick_idle();

	} while (curstate != MULTI_STOP_EXIT);



	local_irq_restore(flags);