powercap/intel_rapl: fix and tidy up error handling

Commit e1399ba20eee ("powercap / RAPL: handle missing MSRs") added
contraint_to_pl() function to return index into an array. But it
can potentially return -EINVAL if powercap layer sends an out of
range constraint ID. This patch adds sanity check.

Unnecessary RAPL domain pointer check is removed since it must be
initialized before calling rapl_unit_xlate().

Fixes: e1399ba20eee ("powercap / RAPL: handle missing MSRs")
Reported-by: Odzioba, Lukasz <lukasz.odzioba@intel.com>
Reported-by: Koss, Marcin <marcin.koss@intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/powercap/intel_rapl.c b/drivers/powercap/intel_rapl.c
index 65ed88a..f6937d0 100644
--- a/drivers/powercap/intel_rapl.c
+++ b/drivers/powercap/intel_rapl.c
@@ -429,6 +429,7 @@
 			return i;
 		}
 	}
+	pr_err("Cannot find matching power limit for constraint %d\n", cid);
 
 	return -EINVAL;
 }
@@ -444,6 +445,10 @@
 	get_online_cpus();
 	rd = power_zone_to_rapl_domain(power_zone);
 	id = contraint_to_pl(rd, cid);
+	if (id < 0) {
+		ret = id;
+		goto set_exit;
+	}
 
 	rp = rd->rp;
 
@@ -483,6 +488,11 @@
 	get_online_cpus();
 	rd = power_zone_to_rapl_domain(power_zone);
 	id = contraint_to_pl(rd, cid);
+	if (id < 0) {
+		ret = id;
+		goto get_exit;
+	}
+
 	switch (rd->rpl[id].prim_id) {
 	case PL1_ENABLE:
 		prim = POWER_LIMIT1;
@@ -499,6 +509,7 @@
 	else
 		*data = val;
 
+get_exit:
 	put_online_cpus();
 
 	return ret;
@@ -514,6 +525,10 @@
 	get_online_cpus();
 	rd = power_zone_to_rapl_domain(power_zone);
 	id = contraint_to_pl(rd, cid);
+	if (id < 0) {
+		ret = id;
+		goto set_time_exit;
+	}
 
 	switch (rd->rpl[id].prim_id) {
 	case PL1_ENABLE:
@@ -525,6 +540,8 @@
 	default:
 		ret = -EINVAL;
 	}
+
+set_time_exit:
 	put_online_cpus();
 	return ret;
 }
@@ -539,6 +556,10 @@
 	get_online_cpus();
 	rd = power_zone_to_rapl_domain(power_zone);
 	id = contraint_to_pl(rd, cid);
+	if (id < 0) {
+		ret = id;
+		goto get_time_exit;
+	}
 
 	switch (rd->rpl[id].prim_id) {
 	case PL1_ENABLE:
@@ -553,6 +574,8 @@
 	}
 	if (!ret)
 		*data = val;
+
+get_time_exit:
 	put_online_cpus();
 
 	return ret;
@@ -694,7 +717,7 @@
 	case ENERGY_UNIT:
 		scale = ENERGY_UNIT_SCALE;
 		/* per domain unit takes precedence */
-		if (rd && rd->domain_energy_unit)
+		if (rd->domain_energy_unit)
 			units = rd->domain_energy_unit;
 		else
 			units = rp->energy_unit;