From: Zqiang <qiang.zhang1211@gmail.com>
For built with CONFIG_PREEMPT_RT=y kernels, running rcutorture
tests resulted in the following splat:
[ 68.797425] rcutorture_one_extend_check during change: Current 0x1 To add 0x1 To remove 0x0 preempt_count() 0x0
[ 68.797533] WARNING: CPU: 2 PID: 512 at kernel/rcu/rcutorture.c:1993 rcutorture_one_extend_check+0x419/0x560 [rcutorture]
[ 68.797601] Call Trace:
[ 68.797602] <TASK>
[ 68.797619] ? lockdep_softirqs_off+0xa5/0x160
[ 68.797631] rcutorture_one_extend+0x18e/0xcc0 [rcutorture 2466dbd2ff34dbaa36049cb323a80c3306ac997c]
[ 68.797646] ? local_clock+0x19/0x40
[ 68.797659] rcu_torture_one_read+0xf0/0x280 [rcutorture 2466dbd2ff34dbaa36049cb323a80c3306ac997c]
[ 68.797678] ? __pfx_rcu_torture_one_read+0x10/0x10 [rcutorture 2466dbd2ff34dbaa36049cb323a80c3306ac997c]
[ 68.797804] ? __pfx_rcu_torture_timer+0x10/0x10 [rcutorture 2466dbd2ff34dbaa36049cb323a80c3306ac997c]
[ 68.797815] rcu-torture: rcu_torture_reader task started
[ 68.797824] rcu-torture: Creating rcu_torture_reader task
[ 68.797824] rcu_torture_reader+0x238/0x580 [rcutorture 2466dbd2ff34dbaa36049cb323a80c3306ac997c]
[ 68.797836] ? kvm_sched_clock_read+0x15/0x30
Disable BH does not change the SOFTIRQ corresponding bits in
preempt_count() for RT kernels, this commit therefore use
softirq_count() to check the if BH is disabled.
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Zqiang <qiang.zhang1211@gmail.com>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
---
kernel/rcu/rcutorture.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 7a07b2590c27..213f23f20a64 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -471,7 +471,7 @@ rcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
!(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) {
started = cur_ops->get_gp_seq();
ts = rcu_trace_clock_local();
- if (preempt_count() & (SOFTIRQ_MASK | HARDIRQ_MASK))
+ if ((preempt_count() & HARDIRQ_MASK) || softirq_count())
longdelay_ms = 5; /* Avoid triggering BH limits. */
mdelay(longdelay_ms);
rtrsp->rt_delay_ms = longdelay_ms;
@@ -2001,7 +2001,7 @@ static void rcutorture_one_extend_check(char *s, int curstate, int new, int old)
return;
WARN_ONCE((curstate & (RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH)) &&
- !(preempt_count() & SOFTIRQ_MASK), ROEC_ARGS);
+ !softirq_count(), ROEC_ARGS);
WARN_ONCE((curstate & (RCUTORTURE_RDR_PREEMPT | RCUTORTURE_RDR_SCHED)) &&
!(preempt_count() & PREEMPT_MASK), ROEC_ARGS);
WARN_ONCE(cur_ops->readlock_nesting &&
@@ -2015,7 +2015,7 @@ static void rcutorture_one_extend_check(char *s, int curstate, int new, int old)
WARN_ONCE(cur_ops->extendables &&
!(curstate & (RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH)) &&
- (preempt_count() & SOFTIRQ_MASK), ROEC_ARGS);
+ softirq_count(), ROEC_ARGS);
/*
* non-preemptible RCU in a preemptible kernel uses preempt_disable()
@@ -2036,6 +2036,9 @@ static void rcutorture_one_extend_check(char *s, int curstate, int new, int old)
if (!IS_ENABLED(CONFIG_PREEMPT_RCU))
mask |= RCUTORTURE_RDR_PREEMPT | RCUTORTURE_RDR_SCHED;
+ if (IS_ENABLED(CONFIG_PREEMPT_RT) && softirq_count())
+ mask |= RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH;
+
WARN_ONCE(cur_ops->readlock_nesting && !(curstate & mask) &&
cur_ops->readlock_nesting() > 0, ROEC_ARGS);
}
--
2.40.1