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authorArnd Bergmann <arnd@arndb.de>2018-06-18 16:47:34 +0200
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2018-07-12 15:42:07 -0700
commit622be33fcbc93e9b672b99ed338369eb5e843ac3 (patch)
tree32387c744ccb51339aa8c2dc1220d0d85ecba360 /kernel/rcu
parent3b745c8969c752601cb68c82a06735363563ab42 (diff)
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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: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcu')
-rw-r--r--kernel/rcu/rcutorture.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 36b9b8266213..049b3735dba8 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -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();