From patchwork Sat Nov 3 15:43:33 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [v2, 02/11] random32: introduce random32_get_bytes() and random32_get_bytes_state() From: Akinobu Mita X-Patchwork-Id: 196857 Message-Id: <1351957422-23243-3-git-send-email-akinobu.mita@gmail.com> To: linux-kernel@vger.kernel.org, akpm@linux-foundation.org Cc: Theodore Ts'o , Artem Bityutskiy , netdev@vger.kernel.org, Adrian Hunter , Akinobu Mita , linux-mtd@lists.infradead.org, David Woodhouse , Eilon Greenstein Date: Sun, 4 Nov 2012 00:43:33 +0900 Add functions to get the requested number of pseudo-random bytes. The difference from get_random_bytes() is that it generates pseudo-random numbers by random32(). It is fast, suitable for generating random bytes for testing, and reproducible if random32_get_bytes_state() is used. Signed-off-by: Akinobu Mita Cc: "Theodore Ts'o" Cc: Artem Bityutskiy Cc: Adrian Hunter Cc: David Woodhouse Cc: linux-mtd@lists.infradead.org Cc: Eilon Greenstein Cc: netdev@vger.kernel.org --- * v2 - rename prandom32_get_bytes to random32_get_bytes_state include/linux/random.h | 2 ++ lib/random32.c | 38 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 40 insertions(+) diff --git a/include/linux/random.h b/include/linux/random.h index bb96f79..4176762 100644 --- a/include/linux/random.h +++ b/include/linux/random.h @@ -27,8 +27,10 @@ unsigned long randomize_range(unsigned long start, unsigned long end, unsigned l u32 random32(void); void srandom32(u32 seed); +void random32_get_bytes(void *buf, int nbytes); u32 random32_state(struct rnd_state *); +void random32_get_bytes_state(struct rnd_state *state, void *buf, int nbytes); /* * Handle minimum values for seeds diff --git a/lib/random32.c b/lib/random32.c index 7a3e0c7..9557417 100644 --- a/lib/random32.c +++ b/lib/random32.c @@ -61,6 +61,44 @@ u32 random32_state(struct rnd_state *state) EXPORT_SYMBOL(random32_state); /** + * random32_get_bytes_state - get the pseudo-random bytes + * @state: pointer to state structure holding seeded state. + * @buf: where to copy the pseudo-random bytes to + * @bytes: the requested number of bytes + * + * This is used for pseudo-randomness with no outside seeding. + * For more random results, use random32_get_bytes(). + */ +void random32_get_bytes_state(struct rnd_state *state, void *buf, int bytes) +{ + unsigned char *p = buf; + + for (; bytes > 0 && ((unsigned long)p) % sizeof(u32); bytes--, p++) + *p = random32_state(state); + + for (; bytes > sizeof(u32) - 1; bytes -= sizeof(u32), p += sizeof(u32)) + *(u32 *)p = random32_state(state); + + for (; bytes > 0; bytes--, p++) + *p = random32_state(state); +} +EXPORT_SYMBOL(random32_get_bytes_state); + +/** + * random32_get_bytes - get the requested number of pseudo-random bytes + * @buf: where to copy the pseudo-random bytes to + * @bytes: the requested number of bytes + */ +void random32_get_bytes(void *buf, int bytes) +{ + struct rnd_state *state = &get_cpu_var(net_rand_state); + + random32_get_bytes_state(state, buf, bytes); + put_cpu_var(state); +} +EXPORT_SYMBOL(random32_get_bytes); + +/** * random32 - pseudo random number generator * * A 32 bit pseudo-random number is generated using a fast