From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-da0-f49.google.com ([209.85.210.49]) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1TSN9p-0001J9-O0 for linux-mtd@lists.infradead.org; Sun, 28 Oct 2012 07:19:43 +0000 Received: by mail-da0-f49.google.com with SMTP id q27so1746291daj.36 for ; Sun, 28 Oct 2012 00:19:35 -0700 (PDT) From: Akinobu Mita To: linux-kernel@vger.kernel.org, akpm@linux-foundation.org Subject: [PATCH 1/9] random32: introduce random32_get_bytes() and prandom32_get_bytes() Date: Sun, 28 Oct 2012 16:18:58 +0900 Message-Id: <1351408746-8623-1-git-send-email-akinobu.mita@gmail.com> Cc: Theodore Ts'o , Artem Bityutskiy , Adrian Hunter , Akinobu Mita , linux-mtd@lists.infradead.org, David Woodhouse List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Add functions to get the requested number of pseudo-random bytes. The difference from get_random_bytes() is that it uses pseudo-random numbers generated by random32. It is fast, suitable for generating random bytes for testing, and reproducible if prandom32 interface 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 --- 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 6330ed4..eedf429b 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 prandom32(struct rnd_state *); +void prandom32_get_bytes(struct rnd_state *state, void *buf, int nbytes); /* * Handle minimum values for seeds diff --git a/lib/random32.c b/lib/random32.c index 938bde5..aee87dd 100644 --- a/lib/random32.c +++ b/lib/random32.c @@ -61,6 +61,44 @@ u32 prandom32(struct rnd_state *state) EXPORT_SYMBOL(prandom32); /** + * prandom32_get_bytes - get the requested number of 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 prandom32_get_bytes(struct rnd_state *state, void *buf, int bytes) +{ + unsigned char *p = buf; + + for (; bytes > 0 && ((unsigned long)p) % sizeof(u32); bytes--, p++) + *p = prandom32(state); + + for (; bytes > sizeof(u32) - 1; bytes -= sizeof(u32), p += sizeof(u32)) + *(u32 *)p = prandom32(state); + + for (; bytes > 0; bytes--, p++) + *p = prandom32(state); +} +EXPORT_SYMBOL(prandom32_get_bytes); + +/** + * 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); + + prandom32_get_bytes(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 -- 1.7.11.7