[PATCH 1/3] tools: pass the unused prctl() args explicitly for PR_FUTEX_HASH

[Bradley Morgan]

prctl() is declared variadic in sys/prctl.h, so an argument the caller
leaves out of the call is whatever that register happens to hold.
Neither file passes all five.  The two SET_SLOTS calls leave arg5 out
and the two GET_SLOTS calls leave arg3, arg4 and arg5 out, so those are
whatever the registers hold.  The kernel does not look at them today so
it works, but it works by luck.  I checked that against a running
kernel, garbage in arg5 on SET_SLOTS and in all three on GET_SLOTS are
accepted.

Pass the zeros.  No functional change.

Signed-off-by: Bradley Morgan <brads@xxxxxxxxxxxxxx>
---
 tools/perf/bench/futex.c                                   | 4 ++--
 tools/testing/selftests/futex/functional/futex_priv_hash.c | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/tools/perf/bench/futex.c b/tools/perf/bench/futex.c
index 1968c9d00b5bb..f4c1c30efe0bd 100644
--- a/tools/perf/bench/futex.c
+++ b/tools/perf/bench/futex.c
@@ -20,7 +20,7 @@ void futex_set_nbuckets_param(struct bench_futex_parameters *params)
 	if (params->nbuckets < 0)
 		return;
 
-	ret = prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_SET_SLOTS, params->nbuckets, 0);
+	ret = prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_SET_SLOTS, params->nbuckets, 0, 0);
 	if (ret) {
 		printf("Requesting %d hash buckets failed: %d/%m\n",
 		       params->nbuckets, ret);
@@ -33,7 +33,7 @@ void futex_print_nbuckets(struct bench_futex_parameters *params)
 	char *futex_hash_mode;
 	int ret;
 
-	ret = prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_GET_SLOTS);
+	ret = prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_GET_SLOTS, 0, 0, 0);
 	if (params->nbuckets >= 0) {
 		if (ret != params->nbuckets) {
 			if (ret < 0) {
diff --git a/tools/testing/selftests/futex/functional/futex_priv_hash.c b/tools/testing/selftests/futex/functional/futex_priv_hash.c
index a8742e2045402..96bfb72362221 100644
--- a/tools/testing/selftests/futex/functional/futex_priv_hash.c
+++ b/tools/testing/selftests/futex/functional/futex_priv_hash.c
@@ -32,12 +32,12 @@ static int counter;
 
 static int futex_hash_slots_set(unsigned int slots)
 {
-	return prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_SET_SLOTS, slots, 0);
+	return prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_SET_SLOTS, slots, 0, 0);
 }
 
 static int futex_hash_slots_get(void)
 {
-	return prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_GET_SLOTS);
+	return prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_GET_SLOTS, 0, 0, 0);
 }
 
 static void futex_hash_slots_set_verify(struct __test_metadata *_metadata, int slots)
-- 
2.53.0