[S390] oprofile: fix min/max interval query checks

oprofile_min_interval and oprofile_max_interval are unsigned, checking
for negative values doesn't work. Change hwsampler_query_min_interval
and hwsampler_query_max_interval to return an unsigned long and
check for a zero value instead.
Reported-by: Nicolas Kaiser <nikai@nikai.net>
Acked-by: Robert Richter <robert.richter@amd.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/oprofile/hwsampler.c

@@ -1021,20 +1021,14 @@ int hwsampler_deallocate()
 	return rc;
 }
 
-long hwsampler_query_min_interval(void)
+unsigned long hwsampler_query_min_interval(void)
 {
-	if (min_sampler_rate)
-		return min_sampler_rate;
-	else
-		return -EINVAL;
+	return min_sampler_rate;
 }
 
-long hwsampler_query_max_interval(void)
+unsigned long hwsampler_query_max_interval(void)
 {
-	if (max_sampler_rate)
-		return max_sampler_rate;
-	else
-		return -EINVAL;
+	return max_sampler_rate;
 }
 
 unsigned long hwsampler_get_sample_overflow_count(unsigned int cpu)

arch/s390/oprofile/hwsampler.h

@@ -102,8 +102,8 @@ int hwsampler_setup(void);
 int hwsampler_shutdown(void);
 int hwsampler_allocate(unsigned long sdbt, unsigned long sdb);
 int hwsampler_deallocate(void);
-long hwsampler_query_min_interval(void);
-long hwsampler_query_max_interval(void);
+unsigned long hwsampler_query_min_interval(void);
+unsigned long hwsampler_query_max_interval(void);
 int hwsampler_start_all(unsigned long interval);
 int hwsampler_stop_all(void);
 int hwsampler_deactivate(unsigned int cpu);

arch/s390/oprofile/init.c

@@ -145,15 +145,11 @@ static int oprofile_hwsampler_init(struct oprofile_operations *ops)
 	 * create hwsampler files only if hwsampler_setup() succeeds.
 	 */
 	oprofile_min_interval = hwsampler_query_min_interval();
-	if (oprofile_min_interval < 0) {
-		oprofile_min_interval = 0;
+	if (oprofile_min_interval == 0)
 		return -ENODEV;
-	}
 	oprofile_max_interval = hwsampler_query_max_interval();
-	if (oprofile_max_interval < 0) {
-		oprofile_max_interval = 0;
+	if (oprofile_max_interval == 0)
 		return -ENODEV;
-	}
 
 	if (oprofile_timer_init(ops))
 		return -ENODEV;