[PATCH v9 07/12] atomic: Add atomic_cond_read_*_timeout()
From: Ankur Arora <hidden>
Date: 2026-02-09 02:32:51
Also in:
bpf, linux-arch, linux-pm, lkml
Subsystem:
atomic infrastructure, documentation, linux kernel memory consistency model (lkmm), the rest · Maintainers:
Will Deacon, Peter Zijlstra, Boqun Feng, Jonathan Corbet, Alan Stern, Andrea Parri, Nicholas Piggin, David Howells, Jade Alglave, Luc Maranget, "Paul E. McKenney", Linus Torvalds
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@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Boqun Feng <redacted>
Signed-off-by: Ankur Arora <redacted>
---
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