From: Hannes Frederic Sowa <han...@stressinduktion.org>
Make the get_random_once() helper generic enough, so that functions
in general would only be called once, where one user of this is then
net_get_random_once().
The only implementation specific call is to get_random_bytes(), all
the rest of this *_once() facility would be duplicated among different
subsystems otherwise. The new do_once() helper will be used by prandom()
later on, but might also be useful for other scenarios as well where a
one-time initialization in often-called, possibly fast-path code could
occur.
Signed-off-by: Hannes Frederic Sowa <han...@stressinduktion.org>
Signed-off-by: Daniel Borkmann <dan...@iogearbox.net>
---
include/linux/once.h | 25 ++++++++++++++++++-------
lib/once.c | 34 +++++++++++++++++++++-------------
2 files changed, 39 insertions(+), 20 deletions(-)
diff --git a/include/linux/once.h b/include/linux/once.h
index 2a83b53..f7a51d5 100644
--- a/include/linux/once.h
+++ b/include/linux/once.h
@@ -3,22 +3,33 @@
#include <linux/types.h>
#include <linux/jump_label.h>
+#include <linux/uio.h>
-bool __get_random_once(void *buf, int nbytes, bool *done,
- struct static_key *once_key);
+bool __do_once(void (*func)(void *arg), void *arg, bool *done,
+ struct static_key *once_key);
-#define get_random_once(buf, nbytes) \
+#define do_once(func, arg) \
({ \
bool ___ret = false; \
static bool ___done = false; \
static struct static_key ___once_key = \
STATIC_KEY_INIT_TRUE; \
if (static_key_true(&___once_key)) \
- ___ret = __get_random_once((buf), \
- (nbytes), \
- &___done, \
- &___once_key); \
+ ___ret = __do_once((func), (arg), \
+ &___done, \
+ &___once_key); \
___ret; \
})
+void get_random_once_kvec(void *arg);
+
+#define get_random_once(buf, nbytes) \
+ ({ \
+ struct kvec __v = { \
+ .iov_base = (buf), \
+ .iov_len = (nbytes), \
+ }; \
+ do_once(get_random_once_kvec, &__v); \
+ })
+
#endif /* _LINUX_ONCE_H */
diff --git a/lib/once.c b/lib/once.c
index 2d5a7de..1e62944 100644
--- a/lib/once.c
+++ b/lib/once.c
@@ -3,36 +3,36 @@
#include <linux/once.h>
#include <linux/random.h>
-struct __random_once_work {
+struct __once_work {
struct work_struct work;
struct static_key *key;
};
-static void __random_once_deferred(struct work_struct *w)
+static void __once_deferred(struct work_struct *w)
{
- struct __random_once_work *work;
+ struct __once_work *work;
- work = container_of(w, struct __random_once_work, work);
+ work = container_of(w, struct __once_work, work);
BUG_ON(!static_key_enabled(work->key));
static_key_slow_dec(work->key);
kfree(work);
}
-static void __random_once_disable_jump(struct static_key *key)
+static void __once_disable_jump(struct static_key *key)
{
- struct __random_once_work *w;
+ struct __once_work *w;
w = kmalloc(sizeof(*w), GFP_ATOMIC);
if (!w)
return;
- INIT_WORK(&w->work, __random_once_deferred);
+ INIT_WORK(&w->work, __once_deferred);
w->key = key;
schedule_work(&w->work);
}
-bool __get_random_once(void *buf, int nbytes, bool *done,
- struct static_key *once_key)
+bool __do_once(void (*func)(void *arg), void *arg, bool *done,
+ struct static_key *once_key)
{
static DEFINE_SPINLOCK(lock);
unsigned long flags;
@@ -43,12 +43,20 @@ bool __get_random_once(void *buf, int nbytes, bool *done,
return false;
}
- get_random_bytes(buf, nbytes);
+ func(arg);
*done = true;
spin_unlock_irqrestore(&lock, flags);
- __random_once_disable_jump(once_key);
-
+ __once_disable_jump(once_key);
return true;
}
-EXPORT_SYMBOL(__get_random_once);
+EXPORT_SYMBOL(__do_once);
+
+/* Helper function for once users. */
+void get_random_once_kvec(void *arg)
+{
+ struct kvec *v = arg;
+
+ get_random_bytes(v->iov_base, v->iov_len);
+}
+EXPORT_SYMBOL(get_random_once_kvec);
--
1.9.3
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