If a CPU runs throughout the stalled grace period without passing
through a quiescent state, RCU priority boosting cannot help.
The rcu_torture_boost_failed() function therefore prints a message
flagging the first such CPU. However, if the stall was instead due to
(for example) RCU's grace-period kthread being starved of CPU, there will
be no such CPU, causing rcu_check_boost_fail() to instead pass back -1
through its cpup CPU-pointer parameter.
Therefore, the current message complains about a mythical CPU -1.
This commit therefore checks for this situation, and notes that all CPUs
have passed through a quiescent state.
Signed-off-by: Paul E. McKenney <paul...@kernel.org>
---
kernel/rcu/rcutorture.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index b4cb7623a8bfc..3ac8c69dd5bc9 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1061,8 +1061,13 @@ static bool rcu_torture_boost_failed(unsigned long
gp_state, unsigned long *star
// At most one persisted message per boost test.
j = jiffies;
lp = READ_ONCE(last_persist);
- if (time_after(j, lp + mininterval) &&
cmpxchg(&last_persist, lp, j) == lp)
- pr_info("Boost inversion persisted: No QS from
CPU %d\n", cpu);
+ if (time_after(j, lp + mininterval) &&
+ cmpxchg(&last_persist, lp, j) == lp) {
+ if (cpu < 0)
+ pr_info("Boost inversion persisted: QS
from all CPUs\n");
+ else
+ pr_info("Boost inversion persisted: No
QS from CPU %d\n", cpu);
+ }
return false; // passed on a technicality
}
VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
--
2.40.1
