[merged mm-nonmm-stable] ucount-use-atomic_long_try_cmpxchg-in-atomic_long_inc_below.patch removed from -mm tree

[merged mm-nonmm-stable] ucount-use-atomic_long_try_cmpxchg-in-atomic_long_inc_below.patch removed from -mm tree

[Andrew Morton]

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The quilt patch titled
     Subject: ucount: use atomic_long_try_cmpxchg() in atomic_long_inc_below()
has been removed from the -mm tree.  Its filename was
     ucount-use-atomic_long_try_cmpxchg-in-atomic_long_inc_below.patch

This patch was dropped because it was merged into the mm-nonmm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Uros Bizjak <ubizjak@gmail.com>
Subject: ucount: use atomic_long_try_cmpxchg() in atomic_long_inc_below()
Date: Mon, 21 Jul 2025 19:45:58 +0200

Use atomic_long_try_cmpxchg() instead of
atomic_long_cmpxchg (*ptr, old, new) == old in atomic_long_inc_below().
x86 CMPXCHG instruction returns success in ZF flag, so this change saves
a compare after cmpxchg (and related move instruction in front of cmpxchg).

Also, atomic_long_try_cmpxchg implicitly assigns old *ptr value to "old"
when cmpxchg fails, enabling further code simplifications.

No functional change intended.

Link: https://lkml.kernel.org/r/20250721174610.28361-2-ubizjak@gmail.com
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Reviewed-by: Alexey Gladkov <legion@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Alexey Gladkov <legion@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: MengEn Sun <mengensun@tencent.com>
Cc: "Thomas Weißschuh" <linux@weissschuh.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 kernel/ucount.c |   14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

--- a/kernel/ucount.c~ucount-use-atomic_long_try_cmpxchg-in-atomic_long_inc_below
+++ a/kernel/ucount.c
@@ -201,16 +201,14 @@ void put_ucounts(struct ucounts *ucounts
 
 static inline bool atomic_long_inc_below(atomic_long_t *v, long u)
 {
-	long c, old;
-	c = atomic_long_read(v);
-	for (;;) {
+	long c = atomic_long_read(v);
+
+	do {
 		if (unlikely(c >= u))
 			return false;
-		old = atomic_long_cmpxchg(v, c, c+1);
-		if (likely(old == c))
-			return true;
-		c = old;
-	}
+	} while (!atomic_long_try_cmpxchg(v, &c, c+1));
+
+	return true;
 }
 
 struct ucounts *inc_ucount(struct user_namespace *ns, kuid_t uid,
_

Patches currently in -mm which might be from ubizjak@gmail.com are