perf/hw_breakpoint: Mark data __ro_after_init

Mark read-only data after initialization as __ro_after_init.

While we are here, turn 'constraints_initialized' into a bool.
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20220829124719.675715-6-elver@google.com

kernel/events/hw_breakpoint.c

@@ -46,7 +46,7 @@ struct bp_cpuinfo {
 };
 
 static DEFINE_PER_CPU(struct bp_cpuinfo, bp_cpuinfo[TYPE_MAX]);
-static int nr_slots[TYPE_MAX];
+static int nr_slots[TYPE_MAX] __ro_after_init;
 
 static struct bp_cpuinfo *get_bp_info(int cpu, enum bp_type_idx type)
 {
@@ -62,7 +62,7 @@ static const struct rhashtable_params task_bps_ht_params = {
 	.automatic_shrinking = true,
 };
 
-static int constraints_initialized;
+static bool constraints_initialized __ro_after_init;
 
 /* Gather the number of total pinned and un-pinned bp in a cpuset */
 struct bp_busy_slots {
@@ -739,7 +739,7 @@ int __init init_hw_breakpoint(void)
 	if (ret)
 		goto err;
 
-	constraints_initialized = 1;
+	constraints_initialized = true;
 
 	perf_pmu_register(&perf_breakpoint, "breakpoint", PERF_TYPE_BREAKPOINT);