perf bench futex: Remove support for IMMUTABLE

It has been decided to remove the support IMMUTABLE futex.
perf bench was one of the eary users for testing purposes. Now that the
API is removed before it could be used in an official release, remove
the bits from perf, too.

Remove Remove support for IMMUTABLE futex.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250710110011.384614-7-bigeasy@linutronix.de

Author: Sebastian Andrzej Siewior

tools/include/uapi/linux/prctl.h

@@ -367,8 +367,6 @@ struct prctl_mm_map {
 /* FUTEX hash management */
 #define PR_FUTEX_HASH			78
 # define PR_FUTEX_HASH_SET_SLOTS	1
-# define FH_FLAG_IMMUTABLE		(1ULL << 0)
 # define PR_FUTEX_HASH_GET_SLOTS	2
-# define PR_FUTEX_HASH_GET_IMMUTABLE	3
 
 #endif /* _LINUX_PRCTL_H */

tools/perf/bench/futex-hash.c

@@ -56,7 +56,6 @@ static struct bench_futex_parameters params = {
 
 static const struct option options[] = {
 	OPT_INTEGER( 'b', "buckets", &params.nbuckets, "Specify amount of hash buckets"),
-	OPT_BOOLEAN( 'I', "immutable", &params.buckets_immutable, "Make the hash buckets immutable"),
 	OPT_UINTEGER('t', "threads", &params.nthreads, "Specify amount of threads"),
 	OPT_UINTEGER('r', "runtime", &params.runtime, "Specify runtime (in seconds)"),
 	OPT_UINTEGER('f', "futexes", &params.nfutexes, "Specify amount of futexes per threads"),

tools/perf/bench/futex-lock-pi.c

@@ -47,7 +47,6 @@ static struct bench_futex_parameters params = {
 
 static const struct option options[] = {
 	OPT_INTEGER( 'b', "buckets", &params.nbuckets, "Specify amount of hash buckets"),
-	OPT_BOOLEAN( 'I', "immutable", &params.buckets_immutable, "Make the hash buckets immutable"),
 	OPT_UINTEGER('t', "threads", &params.nthreads, "Specify amount of threads"),
 	OPT_UINTEGER('r', "runtime", &params.runtime, "Specify runtime (in seconds)"),
 	OPT_BOOLEAN( 'M', "multi",   &params.multi, "Use multiple futexes"),

tools/perf/bench/futex-requeue.c

@@ -52,7 +52,6 @@ static struct bench_futex_parameters params = {
 
 static const struct option options[] = {
 	OPT_INTEGER( 'b', "buckets", &params.nbuckets, "Specify amount of hash buckets"),
-	OPT_BOOLEAN( 'I', "immutable", &params.buckets_immutable, "Make the hash buckets immutable"),
 	OPT_UINTEGER('t', "threads",  &params.nthreads, "Specify amount of threads"),
 	OPT_UINTEGER('q', "nrequeue", &params.nrequeue, "Specify amount of threads to requeue at once"),
 	OPT_BOOLEAN( 's', "silent",   &params.silent, "Silent mode: do not display data/details"),

tools/perf/bench/futex-wake-parallel.c

@@ -63,7 +63,6 @@ static struct bench_futex_parameters params = {
 
 static const struct option options[] = {
 	OPT_INTEGER( 'b', "buckets", &params.nbuckets, "Specify amount of hash buckets"),
-	OPT_BOOLEAN( 'I', "immutable", &params.buckets_immutable, "Make the hash buckets immutable"),
 	OPT_UINTEGER('t', "threads", &params.nthreads, "Specify amount of threads"),
 	OPT_UINTEGER('w', "nwakers", &params.nwakes, "Specify amount of waking threads"),
 	OPT_BOOLEAN( 's', "silent",  &params.silent, "Silent mode: do not display data/details"),

tools/perf/bench/futex-wake.c

@@ -52,7 +52,6 @@ static struct bench_futex_parameters params = {
 
 static const struct option options[] = {
 	OPT_INTEGER( 'b', "buckets", &params.nbuckets, "Specify amount of hash buckets"),
-	OPT_BOOLEAN( 'I', "immutable", &params.buckets_immutable, "Make the hash buckets immutable"),
 	OPT_UINTEGER('t', "threads", &params.nthreads, "Specify amount of threads"),
 	OPT_UINTEGER('w', "nwakes",  &params.nwakes, "Specify amount of threads to wake at once"),
 	OPT_BOOLEAN( 's', "silent",  &params.silent, "Silent mode: do not display data/details"),

tools/perf/bench/futex.c

@@ -9,21 +9,17 @@
 #ifndef PR_FUTEX_HASH
 #define PR_FUTEX_HASH                   78
 # define PR_FUTEX_HASH_SET_SLOTS        1
-# define FH_FLAG_IMMUTABLE              (1ULL << 0)
 # define PR_FUTEX_HASH_GET_SLOTS        2
-# define PR_FUTEX_HASH_GET_IMMUTABLE    3
 #endif // PR_FUTEX_HASH
 
 void futex_set_nbuckets_param(struct bench_futex_parameters *params)
 {
-	unsigned long flags;
 	int ret;
 
 	if (params->nbuckets < 0)
 		return;
 
-	flags = params->buckets_immutable ? FH_FLAG_IMMUTABLE : 0;
-	ret = prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_SET_SLOTS, params->nbuckets, flags);
+	ret = prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_SET_SLOTS, params->nbuckets, 0);
 	if (ret) {
 		printf("Requesting %d hash buckets failed: %d/%m\n",
 		       params->nbuckets, ret);
@@ -47,18 +43,11 @@ void futex_print_nbuckets(struct bench_futex_parameters *params)
 			printf("Requested: %d in usage: %d\n", params->nbuckets, ret);
 			err(EXIT_FAILURE, "prctl(PR_FUTEX_HASH)");
 		}
-		if (params->nbuckets == 0) {
+		if (params->nbuckets == 0)
 			ret = asprintf(&futex_hash_mode, "Futex hashing: global hash");
-		} else {
-			ret = prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_GET_IMMUTABLE);
-			if (ret < 0) {
-				printf("Can't check if the hash is immutable: %m\n");
-				err(EXIT_FAILURE, "prctl(PR_FUTEX_HASH)");
-			}
-			ret = asprintf(&futex_hash_mode, "Futex hashing: %d hash buckets %s",
-				       params->nbuckets,
-				       ret == 1 ? "(immutable)" : "");
-		}
+		else
+			ret = asprintf(&futex_hash_mode, "Futex hashing: %d hash buckets",
+				       params->nbuckets);
 	} else {
 		if (ret <= 0) {
 			ret = asprintf(&futex_hash_mode, "Futex hashing: global hash");

tools/perf/bench/futex.h

@@ -26,7 +26,6 @@ struct bench_futex_parameters {
 	unsigned int nwakes;
 	unsigned int nrequeue;
 	int nbuckets;
-	bool buckets_immutable;
 };
 
 /**

tools/perf/trace/beauty/include/uapi/linux/prctl.h

@@ -367,8 +367,6 @@ struct prctl_mm_map {
 /* FUTEX hash management */
 #define PR_FUTEX_HASH			78
 # define PR_FUTEX_HASH_SET_SLOTS	1
-# define FH_FLAG_IMMUTABLE		(1ULL << 0)
 # define PR_FUTEX_HASH_GET_SLOTS	2
-# define PR_FUTEX_HASH_GET_IMMUTABLE	3
 
 #endif /* _LINUX_PRCTL_H */