linux-kernel - [PATCH v9 07/12] atomic: Add atomic_cond_read_*

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Message-Id: <20260209023153.2661784-8-ankur.a.arora@oracle.com>
Date: Sun,  8 Feb 2026 18:31:48 -0800
From: Ankur Arora <ankur.a.arora@...cle.com>
To: linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-pm@...r.kernel.org,
        bpf@...r.kernel.org
Cc: arnd@...db.de, catalin.marinas@....com, will@...nel.org,
        peterz@...radead.org, akpm@...ux-foundation.org, mark.rutland@....com,
        harisokn@...zon.com, cl@...two.org, ast@...nel.org, rafael@...nel.org,
        daniel.lezcano@...aro.org, memxor@...il.com, zhenglifeng1@...wei.com,
        xueshuai@...ux.alibaba.com, joao.m.martins@...cle.com,
        boris.ostrovsky@...cle.com, konrad.wilk@...cle.com,
        Ankur Arora <ankur.a.arora@...cle.com>,
        Boqun Feng <boqun.feng@...il.com>
Subject: [PATCH v9 07/12] atomic: Add atomic_cond_read_*_timeout()

Add atomic load wrappers, atomic_cond_read_*_timeout() and
atomic64_cond_read_*_timeout() for the cond-load timeout interfaces.

Also add a short description for the atomic_cond_read_{relaxed,acquire}(),
and the atomic_cond_read_{relaxed,acquire}_timeout() interfaces.

Cc: Will Deacon <will@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Boqun Feng <boqun.feng@...il.com>
Signed-off-by: Ankur Arora <ankur.a.arora@...cle.com>
---
Notes:
   - mention these interfaces in Documentation/atomic_t.txt

 Documentation/atomic_t.txt | 14 +++++++++-----
 include/linux/atomic.h     | 10 ++++++++++
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/Documentation/atomic_t.txt b/Documentation/atomic_t.txt
index bee3b1bca9a7..0e53f6ccb558 100644
--- a/Documentation/atomic_t.txt
+++ b/Documentation/atomic_t.txt
@@ -16,6 +16,10 @@ Non-RMW ops:
   atomic_read(), atomic_set()
   atomic_read_acquire(), atomic_set_release()
 
+Non-RMW, non-atomic_t ops:
+
+  atomic_cond_read_{relaxed,acquire}()
+  atomic_cond_read_{relaxed,acquire}_timeout()
 
 RMW atomic operations:
 
@@ -79,11 +83,11 @@ SEMANTICS
 
 Non-RMW ops:
 
-The non-RMW ops are (typically) regular LOADs and STOREs and are canonically
-implemented using READ_ONCE(), WRITE_ONCE(), smp_load_acquire() and
-smp_store_release() respectively. Therefore, if you find yourself only using
-the Non-RMW operations of atomic_t, you do not in fact need atomic_t at all
-and are doing it wrong.
+The non-RMW ops are (typically) regular, or conditional LOADs and STOREs and
+are canonically implemented using READ_ONCE(), WRITE_ONCE(),
+smp_load_acquire() and smp_store_release() respectively. Therefore, if you
+find yourself only using the Non-RMW operations of atomic_t, you do not in
+fact need atomic_t at all and are doing it wrong.
 
 A note for the implementation of atomic_set{}() is that it must not break the
 atomicity of the RMW ops. That is:
diff --git a/include/linux/atomic.h b/include/linux/atomic.h
index 8dd57c3a99e9..5bcb86e07784 100644
--- a/include/linux/atomic.h
+++ b/include/linux/atomic.h
@@ -31,6 +31,16 @@
 #define atomic64_cond_read_acquire(v, c) smp_cond_load_acquire(&(v)->counter, (c))
 #define atomic64_cond_read_relaxed(v, c) smp_cond_load_relaxed(&(v)->counter, (c))
 
+#define atomic_cond_read_acquire_timeout(v, c, e, t) \
+	smp_cond_load_acquire_timeout(&(v)->counter, (c), (e), (t))
+#define atomic_cond_read_relaxed_timeout(v, c, e, t) \
+	smp_cond_load_relaxed_timeout(&(v)->counter, (c), (e), (t))
+
+#define atomic64_cond_read_acquire_timeout(v, c, e, t) \
+	smp_cond_load_acquire_timeout(&(v)->counter, (c), (e), (t))
+#define atomic64_cond_read_relaxed_timeout(v, c, e, t) \
+	smp_cond_load_relaxed_timeout(&(v)->counter, (c), (e), (t))
+
 /*
  * The idea here is to build acquire/release variants by adding explicit
  * barriers on top of the relaxed variant. In the case where the relaxed
-- 
2.31.1