[PATCH 5.4 101/240] random: do not take pool spinlock at boot

Greg Kroah-Hartman
2022-06-20T13:45:17Z

commit afba0b80b977b2a8f16234f2acd982f82710ba33 upstream.

Since rand_initialize() is run while interrupts are still off and
nothing else is running, we don't need to repeatedly take and release
the pool spinlock, especially in the RDSEED loop.

Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/char/random.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -973,10 +973,10 @@ int __init rand_initialize(void)
rv = random_get_entropy();
arch_init = false;
}
- mix_pool_bytes(&rv, sizeof(rv));
+ _mix_pool_bytes(&rv, sizeof(rv));
}
- mix_pool_bytes(&now, sizeof(now));
- mix_pool_bytes(utsname(), sizeof(*(utsname())));
+ _mix_pool_bytes(&now, sizeof(now));
+ _mix_pool_bytes(utsname(), sizeof(*(utsname())));

extract_entropy(base_crng.key, sizeof(base_crng.key));
++base_crng.generation;