[tip: locking/futex] futex: Create private_hash() get/put class

["tip-bot2 for Peter Zijlstra" <tip-bot2@linutronix.de>]

The following commit has been merged into the locking/futex branch of tip:

Commit-ID:     d854e4e7850e6d3ed24f863a877abc2279d60506
Gitweb:        https://git.kernel.org/tip/d854e4e7850e6d3ed24f863a877abc2279d60506
Author:        Peter Zijlstra <peterz@infradead.org>
AuthorDate:    Wed, 16 Apr 2025 18:29:07 +02:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Sat, 03 May 2025 12:02:06 +02:00

futex: Create private_hash() get/put class

This gets us:

  fph = futex_private_hash(key) /* gets fph and inc users */
  futex_private_hash_get(fph)   /* inc users */
  futex_private_hash_put(fph)   /* dec users */

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250416162921.513656-8-bigeasy@linutronix.de
---
 kernel/futex/core.c  | 12 ++++++++++++
 kernel/futex/futex.h |  8 ++++++++
 2 files changed, 20 insertions(+)

diff --git a/kernel/futex/core.c b/kernel/futex/core.c
index 56a5653..6a1d6b1 100644
--- a/kernel/futex/core.c
+++ b/kernel/futex/core.c
@@ -107,6 +107,18 @@ late_initcall(fail_futex_debugfs);
 
 #endif /* CONFIG_FAIL_FUTEX */
 
+struct futex_private_hash *futex_private_hash(void)
+{
+	return NULL;
+}
+
+bool futex_private_hash_get(struct futex_private_hash *fph)
+{
+	return false;
+}
+
+void futex_private_hash_put(struct futex_private_hash *fph) { }
+
 /**
  * futex_hash - Return the hash bucket in the global hash
  * @key:	Pointer to the futex key for which the hash is calculated
diff --git a/kernel/futex/futex.h b/kernel/futex/futex.h
index 77d9b35..bc76e36 100644
--- a/kernel/futex/futex.h
+++ b/kernel/futex/futex.h
@@ -206,10 +206,18 @@ extern struct futex_hash_bucket *futex_hash(union futex_key *key);
 extern void futex_hash_get(struct futex_hash_bucket *hb);
 extern void futex_hash_put(struct futex_hash_bucket *hb);
 
+extern struct futex_private_hash *futex_private_hash(void);
+extern bool futex_private_hash_get(struct futex_private_hash *fph);
+extern void futex_private_hash_put(struct futex_private_hash *fph);
+
 DEFINE_CLASS(hb, struct futex_hash_bucket *,
 	     if (_T) futex_hash_put(_T),
 	     futex_hash(key), union futex_key *key);
 
+DEFINE_CLASS(private_hash, struct futex_private_hash *,
+	     if (_T) futex_private_hash_put(_T),
+	     futex_private_hash(), void);
+
 /**
  * futex_match - Check whether two futex keys are equal
  * @key1:	Pointer to key1