selftests/powerpc/pmu: Use signed long to read perf_event_paranoid

Excerpt from man 2 perf_event_open:

  /proc/sys/kernel/perf_event_paranoid
  The perf_event_paranoid file can be set to restrict access to the
  performance counters.
    2 allow only user-space measurements.
    1 allow both kernel and user measurements (default).
    0 allow access to CPU-specific data but not raw tracepoint samples.
   -1 no restrictions.

require_paranoia_below() should return 0 if perf_event_paranoid is below
a specified level, the value from perf_event_paranoid is read into an
unsigned long so the incorrect value is returned when
perf_event_paranoid is set to -1.

Without this patch applied there is the same number of selftests/powerpc
which skip when /proc/sys/kernel/perf_event_paranoid is set to 1 or -1
but no skips when set to zero.

With this patch applied there are no skipped selftests/powerpc test when
/proc/sys/kernel/perf_event_paranoid is set to 0 or -1.
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

tools/testing/selftests/powerpc/pmu/lib.c

@@ -190,7 +190,7 @@ int parse_proc_maps(void)
 
 bool require_paranoia_below(int level)
 {
-	unsigned long current;
+	long current;
 	char *end, buf[16];
 	FILE *f;
 	int rc;
@@ -208,7 +208,7 @@ bool require_paranoia_below(int level)
 		goto out_close;
 	}
 
-	current = strtoul(buf, &end, 10);
+	current = strtol(buf, &end, 10);
 
 	if (end == buf) {
 		printf("Couldn't parse " PARANOID_PATH "?\n");
@@ -216,7 +216,7 @@ bool require_paranoia_below(int level)
 	}
 
 	if (current >= level)
-		goto out;
+		goto out_close;
 
 	rc = 0;
 out_close: