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-rw-r--r--kernel/jump_label.c53
1 files changed, 53 insertions, 0 deletions
diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index 0dbea887d625..f19aa02a8f48 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -14,6 +14,7 @@
#include <linux/err.h>
#include <linux/static_key.h>
#include <linux/jump_label_ratelimit.h>
+#include <linux/bug.h>
#ifdef HAVE_JUMP_LABEL
@@ -56,6 +57,49 @@ jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
static void jump_label_update(struct static_key *key);
+/*
+ * There are similar definitions for the !HAVE_JUMP_LABEL case in jump_label.h.
+ * The use of 'atomic_read()' requires atomic.h and its problematic for some
+ * kernel headers such as kernel.h and others. Since static_key_count() is not
+ * used in the branch statements as it is for the !HAVE_JUMP_LABEL case its ok
+ * to have it be a function here. Similarly, for 'static_key_enable()' and
+ * 'static_key_disable()', which require bug.h. This should allow jump_label.h
+ * to be included from most/all places for HAVE_JUMP_LABEL.
+ */
+int static_key_count(struct static_key *key)
+{
+ /*
+ * -1 means the first static_key_slow_inc() is in progress.
+ * static_key_enabled() must return true, so return 1 here.
+ */
+ int n = atomic_read(&key->enabled);
+
+ return n >= 0 ? n : 1;
+}
+EXPORT_SYMBOL_GPL(static_key_count);
+
+void static_key_enable(struct static_key *key)
+{
+ int count = static_key_count(key);
+
+ WARN_ON_ONCE(count < 0 || count > 1);
+
+ if (!count)
+ static_key_slow_inc(key);
+}
+EXPORT_SYMBOL_GPL(static_key_enable);
+
+void static_key_disable(struct static_key *key)
+{
+ int count = static_key_count(key);
+
+ WARN_ON_ONCE(count < 0 || count > 1);
+
+ if (count)
+ static_key_slow_dec(key);
+}
+EXPORT_SYMBOL_GPL(static_key_disable);
+
void static_key_slow_inc(struct static_key *key)
{
int v, v1;
@@ -235,6 +279,15 @@ void __init jump_label_init(void)
struct static_key *key = NULL;
struct jump_entry *iter;
+ /*
+ * Since we are initializing the static_key.enabled field with
+ * with the 'raw' int values (to avoid pulling in atomic.h) in
+ * jump_label.h, let's make sure that is safe. There are only two
+ * cases to check since we initialize to 0 or 1.
+ */
+ BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0);
+ BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1);
+
jump_label_lock();
jump_label_sort_entries(iter_start, iter_stop);