From: Alexei Starovoitov <ast@plumgrid•com>
To: Daniel Borkmann <daniel@iogearbox•net>, davem@davemloft•net
Cc: hannes@stressinduktion•org, netdev@vger•kernel.org
Subject: Re: [PATCH net-next 2/5] once: make helper generic for calling function once
Date: Wed, 7 Oct 2015 09:16:49 -0700 [thread overview]
Message-ID: <56154571.7050900@plumgrid.com> (raw)
In-Reply-To: <68b03e7c018609b0b56e74346e3f22ac0ad67f28.1444224502.git.daniel@iogearbox.net>
On 10/7/15 6:43 AM, Daniel Borkmann wrote:
> From: Hannes Frederic Sowa<hannes@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<hannes@stressinduktion•org>
> Signed-off-by: Daniel Borkmann<daniel@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; \
})
next prev parent reply other threads:[~2015-10-07 16:16 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-07 13:43 [PATCH net-next 0/5] BPF/random32 updates Daniel Borkmann
2015-10-07 13:43 ` [PATCH net-next 1/5] net: move net_get_random_once to lib Daniel Borkmann
2015-10-07 13:43 ` [PATCH net-next 2/5] once: make helper generic for calling function once Daniel Borkmann
2015-10-07 16:16 ` Alexei Starovoitov [this message]
2015-10-07 21:00 ` Daniel Borkmann
2015-10-07 13:43 ` [PATCH net-next 3/5] random32: add prandom_seed_full_state helper Daniel Borkmann
2015-10-07 13:43 ` [PATCH net-next 4/5] random32: add prandom_init_once helper for own rngs Daniel Borkmann
2015-10-07 16:32 ` Alexei Starovoitov
2015-10-07 13:43 ` [PATCH net-next 5/5] bpf: split state from prandom_u32() and consolidate {c,e}BPF prngs Daniel Borkmann
2015-10-07 16:38 ` Alexei Starovoitov
2015-10-07 21:01 ` Daniel Borkmann
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