Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 622be33f authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Paul E. McKenney
Browse files

rcutorture: Use monotonic timestamp for stall detection 



The get_seconds() call is deprecated because it overflows on 32-bit
architectures. The algorithm in rcu_torture_stall() can deal with
the overflow, but another problem here is that using a CLOCK_REALTIME
stamp can lead to a false-positive stall warning when a settimeofday()
happens concurrently.

Using ktime_get_seconds() instead avoids those issues and will never
overflow. The added cast to 'unsigned long' however is necessary to
make ULONG_CMP_LT() work correctly.

Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 3b745c89

kernel/rcu/rcutorture.c

+3 −2
Original line number Diff line number Diff line
@@ -1622,7 +1622,7 @@ static int rcu_torture_stall(void *args) 
		VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");

	}

	if (!kthread_should_stop()) {

		stop_at = get_seconds() + stall_cpu;

		stop_at = ktime_get_seconds() + stall_cpu;

		/* RCU CPU stall is expected behavior in following code. */

		rcu_read_lock();

		if (stall_cpu_irqsoff)
@@ -1631,7 +1631,8 @@ static int rcu_torture_stall(void *args) 
			preempt_disable();

		pr_alert("rcu_torture_stall start on CPU %d.\n",

			 smp_processor_id());

		while (ULONG_CMP_LT(get_seconds(), stop_at))

		while (ULONG_CMP_LT((unsigned long)ktime_get_seconds(),

				    stop_at))

			continue;  /* Induce RCU CPU stall warning. */

		if (stall_cpu_irqsoff)

			local_irq_enable();