From a5bde5d8fde8a8cb28e59a672d5ddc5b9c1e7656 Mon Sep 17 00:00:00 2001 From: Breno Leitao Date: Wed, 5 Aug 2026 07:52:36 -0700 Subject: workqueue: skip the node_nr_active update for non-unbound workqueues apply_wqattrs_commit() updates node_nr_active->max unconditionally. wq->node_nr_active[] is only allocated for unbound workqueues, so guard the call before per-cpu workqueues start using this path. No functional change: only unbound workqueues reach apply_wqattrs_*() today. Signed-off-by: Breno Leitao Signed-off-by: Tejun Heo --- ...b__after_atomic-is-stronger-than-acquire.litmus | 32 ++++++++++++++++++++ ...Atomic-RMW-ops-are-atomic-WRT-atomic_set.litmus | 25 ++++++++++++++++ .../atomic/cmpxchg-fail-ordered-1.litmus | 35 ++++++++++++++++++++++ .../atomic/cmpxchg-fail-ordered-2.litmus | 30 +++++++++++++++++++ .../atomic/cmpxchg-fail-unordered-1.litmus | 34 +++++++++++++++++++++ .../atomic/cmpxchg-fail-unordered-2.litmus | 30 +++++++++++++++++++ 6 files changed, 186 insertions(+) create mode 100644 Documentation/litmus-tests/atomic/Atomic-RMW+mb__after_atomic-is-stronger-than-acquire.litmus create mode 100644 Documentation/litmus-tests/atomic/Atomic-RMW-ops-are-atomic-WRT-atomic_set.litmus create mode 100644 Documentation/litmus-tests/atomic/cmpxchg-fail-ordered-1.litmus create mode 100644 Documentation/litmus-tests/atomic/cmpxchg-fail-ordered-2.litmus create mode 100644 Documentation/litmus-tests/atomic/cmpxchg-fail-unordered-1.litmus create mode 100644 Documentation/litmus-tests/atomic/cmpxchg-fail-unordered-2.litmus (limited to 'Documentation/litmus-tests/atomic') diff --git a/Documentation/litmus-tests/atomic/Atomic-RMW+mb__after_atomic-is-stronger-than-acquire.litmus b/Documentation/litmus-tests/atomic/Atomic-RMW+mb__after_atomic-is-stronger-than-acquire.litmus new file mode 100644 index 000000000..9a8e31a44 --- /dev/null +++ b/Documentation/litmus-tests/atomic/Atomic-RMW+mb__after_atomic-is-stronger-than-acquire.litmus @@ -0,0 +1,32 @@ +C Atomic-RMW+mb__after_atomic-is-stronger-than-acquire + +(* + * Result: Never + * + * Test that an atomic RMW followed by a smp_mb__after_atomic() is + * stronger than a normal acquire: both the read and write parts of + * the RMW are ordered before the subsequential memory accesses. + *) + +{ +} + +P0(int *x, atomic_t *y) +{ + int r0; + int r1; + + r0 = READ_ONCE(*x); + smp_rmb(); + r1 = atomic_read(y); +} + +P1(int *x, atomic_t *y) +{ + atomic_inc(y); + smp_mb__after_atomic(); + WRITE_ONCE(*x, 1); +} + +exists +(0:r0=1 /\ 0:r1=0) diff --git a/Documentation/litmus-tests/atomic/Atomic-RMW-ops-are-atomic-WRT-atomic_set.litmus b/Documentation/litmus-tests/atomic/Atomic-RMW-ops-are-atomic-WRT-atomic_set.litmus new file mode 100644 index 000000000..ffd4d3e79 --- /dev/null +++ b/Documentation/litmus-tests/atomic/Atomic-RMW-ops-are-atomic-WRT-atomic_set.litmus @@ -0,0 +1,25 @@ +C Atomic-RMW-ops-are-atomic-WRT-atomic_set + +(* + * Result: Never + * + * Test that atomic_set() cannot break the atomicity of atomic RMWs. + * NOTE: This requires herd7 7.56 or later which supports "(void)expr". + *) + +{ + atomic_t v = ATOMIC_INIT(1); +} + +P0(atomic_t *v) +{ + (void)atomic_add_unless(v, 1, 0); +} + +P1(atomic_t *v) +{ + atomic_set(v, 0); +} + +exists +(v=2) diff --git a/Documentation/litmus-tests/atomic/cmpxchg-fail-ordered-1.litmus b/Documentation/litmus-tests/atomic/cmpxchg-fail-ordered-1.litmus new file mode 100644 index 000000000..c0f93dc07 --- /dev/null +++ b/Documentation/litmus-tests/atomic/cmpxchg-fail-ordered-1.litmus @@ -0,0 +1,35 @@ +C cmpxchg-fail-ordered-1 + +(* + * Result: Never + * + * Demonstrate that a failing cmpxchg() operation will act as a full + * barrier when followed by smp_mb__after_atomic(). + *) + +{} + +P0(int *x, int *y, int *z) +{ + int r0; + int r1; + + WRITE_ONCE(*x, 1); + r1 = cmpxchg(z, 1, 0); + smp_mb__after_atomic(); + r0 = READ_ONCE(*y); +} + +P1(int *x, int *y, int *z) +{ + int r0; + int r1; + + WRITE_ONCE(*y, 1); + r1 = cmpxchg(z, 1, 0); + smp_mb__after_atomic(); + r0 = READ_ONCE(*x); +} + +locations[0:r1;1:r1] +exists (0:r0=0 /\ 1:r0=0) diff --git a/Documentation/litmus-tests/atomic/cmpxchg-fail-ordered-2.litmus b/Documentation/litmus-tests/atomic/cmpxchg-fail-ordered-2.litmus new file mode 100644 index 000000000..5c06054f4 --- /dev/null +++ b/Documentation/litmus-tests/atomic/cmpxchg-fail-ordered-2.litmus @@ -0,0 +1,30 @@ +C cmpxchg-fail-ordered-2 + +(* + * Result: Never + * + * Demonstrate use of smp_mb__after_atomic() to make a failing cmpxchg + * operation have acquire ordering. + *) + +{} + +P0(int *x, int *y) +{ + int r1; + + WRITE_ONCE(*x, 1); + r1 = cmpxchg(y, 0, 1); +} + +P1(int *x, int *y) +{ + int r1; + int r2; + + r1 = cmpxchg(y, 0, 1); + smp_mb__after_atomic(); + r2 = READ_ONCE(*x); +} + +exists (0:r1=0 /\ 1:r1=1 /\ 1:r2=0) diff --git a/Documentation/litmus-tests/atomic/cmpxchg-fail-unordered-1.litmus b/Documentation/litmus-tests/atomic/cmpxchg-fail-unordered-1.litmus new file mode 100644 index 000000000..39ea1f56a --- /dev/null +++ b/Documentation/litmus-tests/atomic/cmpxchg-fail-unordered-1.litmus @@ -0,0 +1,34 @@ +C cmpxchg-fail-unordered-1 + +(* + * Result: Sometimes + * + * Demonstrate that a failing cmpxchg() operation does not act as a + * full barrier. (In contrast, a successful cmpxchg() does act as a + * full barrier.) + *) + +{} + +P0(int *x, int *y, int *z) +{ + int r0; + int r1; + + WRITE_ONCE(*x, 1); + r1 = cmpxchg(z, 1, 0); + r0 = READ_ONCE(*y); +} + +P1(int *x, int *y, int *z) +{ + int r0; + int r1; + + WRITE_ONCE(*y, 1); + r1 = cmpxchg(z, 1, 0); + r0 = READ_ONCE(*x); +} + +locations[0:r1;1:r1] +exists (0:r0=0 /\ 1:r0=0) diff --git a/Documentation/litmus-tests/atomic/cmpxchg-fail-unordered-2.litmus b/Documentation/litmus-tests/atomic/cmpxchg-fail-unordered-2.litmus new file mode 100644 index 000000000..61aab24a4 --- /dev/null +++ b/Documentation/litmus-tests/atomic/cmpxchg-fail-unordered-2.litmus @@ -0,0 +1,30 @@ +C cmpxchg-fail-unordered-2 + +(* + * Result: Sometimes + * + * Demonstrate that a failing cmpxchg() operation does not act as either + * an acquire release operation. (In contrast, a successful cmpxchg() + * does act as both an acquire and a release operation.) + *) + +{} + +P0(int *x, int *y) +{ + int r1; + + WRITE_ONCE(*x, 1); + r1 = cmpxchg(y, 0, 1); +} + +P1(int *x, int *y) +{ + int r1; + int r2; + + r1 = cmpxchg(y, 0, 1); + r2 = READ_ONCE(*x); +} + +exists (0:r1=0 /\ 1:r1=1 /\ 1:r2=0) -- cgit v1.3.1