workqueue: skip the node_nr_active update for non-unbound workqueuesgrafted

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 <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>

6 files changed, 186 insertions, 0 deletions

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)