On 10/07/2015 06:16 PM, Alexei Starovoitov wrote:
On 10/7/15 6:43 AM, Daniel Borkmann wrote:
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(-)
looking at the patch 1 the once.c file name really looked out of place,
but this patch makes it fit. Interesting helper, though
get_random_once_kvec() and kvec are not pretty, since they take extra
stack and being inited even when static_key is disabled.
Instead is it possible to split do_once into two parts then
your macro can have varags and kvec/extra_helper can be removed like:
#define do_once(func, ...) \
({ \
bool ___ret = false; \
static bool ___done = false; \
static struct static_key ___once_key = \
STATIC_KEY_INIT_TRUE; \
if (static_key_true(&___once_key)) { \
__do_once_lock(&___done); \
func(##__VA_ARGS__); \
__do_once_unlock(&_done, &___once_key);\
} \
___ret; \
})
Thanks, good point, I do like it! After reworking this, the outcome of
the new DO_ONCE() is a bit different than above. I'll send out v2 very
soon to show the code result.
Thanks,
Daniel
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
