futex: Move futex related mm_struct data into a struct

Having all these members in mm_struct along with the required #ifdeffery is
annoying, does not allow efficient initializing of the data with
memset() and makes extending it tedious.

Move it into a data structure and fix up all usage sites.

The extra struct for the private hash is intentional to make integration of
other conditional mechanisms easier in terms of initialization and separation.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260602090535.407756793@kernel.org

2 files changed, 37 insertions, 11 deletions

diff --git a/include/linux/futex_types.h b/include/linux/futex_types.h
index 9c6c0dc4148d..d41557d2790d 100644
--- a/include/linux/futex_types.h
+++ b/include/linux/futex_types.h
@@ -3,6 +3,7 @@
 #define _LINUX_FUTEX_TYPES_H
 
 #ifdef CONFIG_FUTEX
+#include <linux/compiler_types.h>
 #include <linux/mutex_types.h>
 #include <linux/types.h>
 
@@ -29,8 +30,41 @@ struct futex_sched_data {
 	struct mutex				exit_mutex;
 	unsigned int				state;
 };
-#else
+
+#ifdef CONFIG_FUTEX_PRIVATE_HASH
+/**
+ * struct futex_mm_phash - Futex private hash related per MM data
+ * @lock:	Mutex to protect the private hash operations
+ * @hash:	RCU managed pointer to the private hash
+ * @hash_new:	Pointer to a newly allocated private hash
+ * @batches:	Batch state for RCU synchronization
+ * @rcu:	RCU head for call_rcu()
+ * @atomic:	Aggregate value for @hash_ref
+ * @ref:	Per CPU reference counter for a private hash
+ */
+struct futex_mm_phash {
+	struct mutex			lock;
+	struct futex_private_hash	__rcu *hash;
+	struct futex_private_hash	*hash_new;
+	unsigned long			batches;
+	struct rcu_head			rcu;
+	atomic_long_t			atomic;
+	unsigned int			__percpu *ref;
+};
+#else  /* CONFIG_FUTEX_ROBUST_UNLOCK */
+struct futex_mm_phash { };
+#endif /* !CONFIG_FUTEX_ROBUST_UNLOCK */
+
+/**
+ * struct futex_mm_data - Futex related per MM data
+ * @phash:	Futex private hash related data
+ */
+struct futex_mm_data {
+	struct futex_mm_phash		phash;
+};
+#else  /* CONFIG_FUTEX */
 struct futex_sched_data { };
+struct futex_mm_data { };
 #endif /* !CONFIG_FUTEX */
 
 #endif /* _LINUX_FUTEX_TYPES_H */
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index a308e2c23b82..1d0c8d8875aa 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -20,6 +20,7 @@
 #include <linux/seqlock.h>
 #include <linux/percpu_counter.h>
 #include <linux/types.h>
+#include <linux/futex_types.h>
 #include <linux/rseq_types.h>
 #include <linux/bitmap.h>
 
@@ -1270,16 +1271,7 @@ struct mm_struct {
 		 */
 		seqcount_t mm_lock_seq;
 #endif
-#ifdef CONFIG_FUTEX_PRIVATE_HASH
-		struct mutex			futex_hash_lock;
-		struct futex_private_hash	__rcu *futex_phash;
-		struct futex_private_hash	*futex_phash_new;
-		/* futex-ref */
-		unsigned long			futex_batches;
-		struct rcu_head			futex_rcu;
-		atomic_long_t			futex_atomic;
-		unsigned int			__percpu *futex_ref;
-#endif
+		struct futex_mm_data	futex;
 
 		unsigned long hiwater_rss; /* High-watermark of RSS usage */
 		unsigned long hiwater_vm;  /* High-water virtual memory usage */