| From | Paul Gortmaker <> | Subject | [v2.6.34-stable 162/165] random: Add comment to random_initialize() | Date | Wed, 15 Aug 2012 15:48:26 -0400 |
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From: Tony Luck <tony.luck@intel.com>
------------------- This is a commit scheduled for the next v2.6.34 longterm release. http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git If you see a problem with using this for longterm, please comment. -------------------
commit cbc96b7594b5691d61eba2db8b2ea723645be9ca upstream.
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 <tytso@mit.edu> Signed-off-by: Tony Luck <tony.luck@intel.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> --- drivers/char/random.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
diff --git a/drivers/char/random.c b/drivers/char/random.c index 1644b8e..7e19406 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1088,6 +1088,16 @@ 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); -- 1.7.12.rc2
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