s390/rwlock: Add contention tracepoints to rwlock slowpath

Instrument arch_read_lock_wait() and arch_write_lock_wait() with
trace_contention_begin() and trace_contention_end().

These tracepoints are used by lock contention analysis tools such as
perf lock contention to identify contended rwlocks and measure wait
times. The generic implementation in kernel/locking/qrwlock.c already
emits the same events from its read and write slowpaths.

For arch_read_lock_wait(), the in_interrupt() fast-path is intentionally
left outside the tracepoint scope. That path spins without entering the
wait queue, so it does not represent queue-based contention and its
duration is not comparable to the normal slowpath. This matches the
behaviour of queued_read_lock_slowpath() in qrwlock.c.

The include for <trace/events/lock.h> is already present from
commit ffa796cc1f45 ("s390/spinlock: Add contention tracepoints to
lock slowpath").

Signed-off-by: Jan Polensky <japo@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

0 files changed, 0 insertions, 0 deletions