From: Tony Luck Date: Mon, 23 Jul 2012 16:47:57 +0000 (-0700) Subject: random: Add comment to random_initialize() X-Git-Tag: upstream/snapshot3+hdmi~6898^2~2 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=cbc96b7594b5691d61eba2db8b2ea723645be9ca;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git random: Add comment to random_initialize() Many platforms have per-machine instance data (serial numbers, asset tags, etc.) squirreled away in areas that are accessed during early system bringup. Mixing this data into the random pools has a very high value in providing better random data, so we should allow (and even encourage) architecture code to call add_device_randomness() from the setup_arch() paths. However, this limits our options for internal structure of the random driver since random_initialize() is not called until long after setup_arch(). Add a big fat comment to rand_initialize() spelling out this requirement. Suggested-by: Theodore Ts'o Signed-off-by: Tony Luck Signed-off-by: Theodore Ts'o --- diff --git a/drivers/char/random.c b/drivers/char/random.c index 9793b40..1a2dfa8 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1087,6 +1087,16 @@ static void init_std_data(struct entropy_store *r) mix_pool_bytes(r, utsname(), sizeof(*(utsname())), NULL); } +/* + * Note that setup_arch() may call add_device_randomness() + * long before we get here. This allows seeding of the pools + * with some platform dependent data very early in the boot + * process. But it limits our options here. We must use + * statically allocated structures that already have all + * initializations complete at compile time. We should also + * take care not to overwrite the precious per platform data + * we were given. + */ static int rand_initialize(void) { init_std_data(&input_pool);