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authorTony Luck <tony.luck@intel.com>2012-07-23 09:47:57 -0700
committerTheodore Ts'o <tytso@mit.edu>2012-07-24 13:16:41 -0400
commitcbc96b7594b5691d61eba2db8b2ea723645be9ca (patch)
tree440e0d132abdb6b1d03e9440c803c0f7e2db38fc /drivers/char/random.c
parentb4237003cff66084ebeb502412d9cee392e6f52f (diff)
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 <tytso@mit.edu> Signed-off-by: Tony Luck <tony.luck@intel.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'drivers/char/random.c')
-rw-r--r--drivers/char/random.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 9793b40f5754..1a2dfa816041 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);