rcutorture: Update rcutorture_one_extend_check() for lazy preemption

The rcutorture_one_extend_check() function's last check assumes that
if cur_ops->readlock_nesting() returns greater than zero, either the
RCUTORTURE_RDR_RCU_1 or the RCUTORTURE_RDR_RCU_2 bit must be set, that
is, there must be at least one rcu_read_lock() in effect.

This works for preemptible RCU and for non-preemptible RCU running in
a non-preemptible kernel.  But it fails for non-preemptible RCU running
in a preemptible kernel because then RCU's cur_ops->readlock_nesting()
function, which is rcu_torture_readlock_nesting(), will return
the PREEMPT_MASK mask bits from preempt_count().  The result will
be greater than zero if preemption is disabled, including by the
RCUTORTURE_RDR_PREEMPT and RCUTORTURE_RDR_SCHED bits.

This commit therefore adjusts this check to take into account the case
fo non-preemptible RCU running in a preemptible kernel.

[boqun: Fix the if condition and add comment]

Reported-by: kernel test robot <[email protected]>
Closes: https://lore.kernel.org/oe-lkp/[email protected]
Co-developed-by: Boqun Feng <[email protected]>
Signed-off-by: Boqun Feng <[email protected]>
Co-developed-by: Joel Fernandes <[email protected]>
Signed-off-by: Joel Fernandes <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>
Tested-by: kernel test robot <[email protected]>
Signed-off-by: Boqun Feng <[email protected]>

0 files changed, 0 insertions, 0 deletions