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-rw-r--r--scripts/atomic/fallbacks/fetch_add_unless23
1 files changed, 23 insertions, 0 deletions
diff --git a/scripts/atomic/fallbacks/fetch_add_unless b/scripts/atomic/fallbacks/fetch_add_unless
new file mode 100644
index 000000000000..d2c091db7eae
--- /dev/null
+++ b/scripts/atomic/fallbacks/fetch_add_unless
@@ -0,0 +1,23 @@
+cat << EOF
+/**
+ * ${atomic}_fetch_add_unless - add unless the number is already a given value
+ * @v: pointer of type ${atomic}_t
+ * @a: the amount to add to v...
+ * @u: ...unless v is equal to u.
+ *
+ * Atomically adds @a to @v, so long as @v was not already @u.
+ * Returns original value of @v
+ */
+static inline ${int}
+${atomic}_fetch_add_unless(${atomic}_t *v, ${int} a, ${int} u)
+{
+ ${int} c = ${atomic}_read(v);
+
+ do {
+ if (unlikely(c == u))
+ break;
+ } while (!${atomic}_try_cmpxchg(v, &c, c + a));
+
+ return c;
+}
+EOF