From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org,
Dominik Brodowski <linux@dominikbrodowski.net>,
"Jason A. Donenfeld" <Jason@zx2c4.com>
Subject: [PATCH 5.18 30/47] random: move initialization out of reseeding hot path
Date: Fri, 27 May 2022 10:50:10 +0200 [thread overview]
Message-ID: <20220527084806.466052475@linuxfoundation.org> (raw)
In-Reply-To: <20220527084801.223648383@linuxfoundation.org>
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
commit 68c9c8b192c6dae9be6278e98ee44029d5da2d31 upstream.
Initialization happens once -- by way of credit_init_bits() -- and then
it never happens again. Therefore, it doesn't need to be in
crng_reseed(), which is a hot path that is called multiple times. It
also doesn't make sense to have there, as initialization activity is
better associated with initialization routines.
After the prior commit, crng_reseed() now won't be called by multiple
concurrent callers, which means that we can safely move the
"finialize_init" logic into crng_init_bits() unconditionally.
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 | 42 +++++++++++++++++++-----------------------
1 file changed, 19 insertions(+), 23 deletions(-)
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -264,7 +264,6 @@ static void crng_reseed(void)
unsigned long flags;
unsigned long next_gen;
u8 key[CHACHA_KEY_SIZE];
- bool finalize_init = false;
extract_entropy(key, sizeof(key));
@@ -281,28 +280,10 @@ static void crng_reseed(void)
++next_gen;
WRITE_ONCE(base_crng.generation, next_gen);
WRITE_ONCE(base_crng.birth, jiffies);
- if (!crng_ready()) {
+ if (!crng_ready())
crng_init = CRNG_READY;
- finalize_init = true;
- }
spin_unlock_irqrestore(&base_crng.lock, flags);
memzero_explicit(key, sizeof(key));
- if (finalize_init) {
- process_random_ready_list();
- wake_up_interruptible(&crng_init_wait);
- kill_fasync(&fasync, SIGIO, POLL_IN);
- pr_notice("crng init done\n");
- if (unseeded_warning.missed) {
- pr_notice("%d get_random_xx warning(s) missed due to ratelimiting\n",
- unseeded_warning.missed);
- unseeded_warning.missed = 0;
- }
- if (urandom_warning.missed) {
- pr_notice("%d urandom warning(s) missed due to ratelimiting\n",
- urandom_warning.missed);
- urandom_warning.missed = 0;
- }
- }
}
/*
@@ -834,10 +815,25 @@ static void credit_init_bits(size_t nbit
new = min_t(unsigned int, POOL_BITS, orig + add);
} while (cmpxchg(&input_pool.init_bits, orig, new) != orig);
- if (orig < POOL_READY_BITS && new >= POOL_READY_BITS)
- crng_reseed();
- else if (orig < POOL_EARLY_BITS && new >= POOL_EARLY_BITS) {
+ if (orig < POOL_READY_BITS && new >= POOL_READY_BITS) {
+ crng_reseed(); /* Sets crng_init to CRNG_READY under base_crng.lock. */
+ process_random_ready_list();
+ wake_up_interruptible(&crng_init_wait);
+ kill_fasync(&fasync, SIGIO, POLL_IN);
+ pr_notice("crng init done\n");
+ if (unseeded_warning.missed) {
+ pr_notice("%d get_random_xx warning(s) missed due to ratelimiting\n",
+ unseeded_warning.missed);
+ unseeded_warning.missed = 0;
+ }
+ if (urandom_warning.missed) {
+ pr_notice("%d urandom warning(s) missed due to ratelimiting\n",
+ urandom_warning.missed);
+ urandom_warning.missed = 0;
+ }
+ } else if (orig < POOL_EARLY_BITS && new >= POOL_EARLY_BITS) {
spin_lock_irqsave(&base_crng.lock, flags);
+ /* Check if crng_init is CRNG_EMPTY, to avoid race with crng_reseed(). */
if (crng_init == CRNG_EMPTY) {
extract_entropy(base_crng.key, sizeof(base_crng.key));
crng_init = CRNG_EARLY;
next prev parent reply other threads:[~2022-05-27 8:55 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-27 8:49 [PATCH 5.18 00/47] 5.18.1-rc1 review Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.18 01/47] lockdown: also lock down previous kgdb use Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.18 02/47] HID: amd_sfh: Add support for sensor discovery Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.18 03/47] random: fix sysctl documentation nits Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.18 04/47] init: call time_init() before rand_initialize() Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.18 05/47] ia64: define get_cycles macro for arch-override Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.18 06/47] s390: " Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.18 07/47] parisc: " Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.18 08/47] alpha: " Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.18 09/47] powerpc: " Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.18 10/47] timekeeping: Add raw clock fallback for random_get_entropy() Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.18 11/47] m68k: use fallback for random_get_entropy() instead of zero Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.18 12/47] riscv: " Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.18 13/47] mips: use fallback for random_get_entropy() instead of just c0 random Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.18 14/47] arm: use fallback for random_get_entropy() instead of zero Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.18 15/47] nios2: " Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.18 16/47] x86/tsc: Use " Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.18 17/47] um: use " Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.18 18/47] sparc: " Greg Kroah-Hartman
2022-05-27 8:49 ` [PATCH 5.18 19/47] xtensa: " Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.18 20/47] random: insist on random_get_entropy() existing in order to simplify Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.18 21/47] random: do not use batches when !crng_ready() Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.18 22/47] random: use first 128 bits of input as fast init Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.18 23/47] random: do not pretend to handle premature next security model Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.18 24/47] random: order timer entropy functions below interrupt functions Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.18 25/47] random: do not use input pool from hard IRQs Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.18 26/47] random: help compiler out with fast_mix() by using simpler arguments Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.18 27/47] siphash: use one source of truth for siphash permutations Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.18 28/47] random: use symbolic constants for crng_init states Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.18 29/47] random: avoid initializing twice in credit race Greg Kroah-Hartman
2022-05-27 8:50 ` Greg Kroah-Hartman [this message]
2022-05-27 8:50 ` [PATCH 5.18 31/47] random: remove ratelimiting for in-kernel unseeded randomness Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.18 32/47] random: use proper jiffies comparison macro Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.18 33/47] random: handle latent entropy and command line from random_init() Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.18 34/47] random: credit architectural init the exact amount Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.18 35/47] random: use static branch for crng_ready() Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.18 36/47] random: remove extern from functions in header Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.18 37/47] random: use proper return types on get_random_{int,long}_wait() Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.18 38/47] random: make consistent use of buf and len Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.18 39/47] random: move initialization functions out of hot pages Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.18 40/47] random: move randomize_page() into mm where it belongs Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.18 41/47] random: unify batched entropy implementations Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.18 42/47] random: convert to using fops->read_iter() Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.18 43/47] random: convert to using fops->write_iter() Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.18 44/47] random: wire up fops->splice_{read,write}_iter() Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.18 45/47] random: check for signals after page of pool writes Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.18 46/47] ACPI: sysfs: Fix BERT error region memory mapping Greg Kroah-Hartman
2022-05-27 8:50 ` [PATCH 5.18 47/47] ALSA: ctxfi: Add SB046x PCI ID Greg Kroah-Hartman
2022-05-27 22:40 ` [PATCH 5.18 00/47] 5.18.1-rc1 review Guenter Roeck
2022-05-28 1:53 ` Justin Forbes
2022-05-28 2:24 ` Ron Economos
2022-05-28 2:50 ` Bagas Sanjaya
2022-05-28 11:16 ` Naresh Kamboju
2022-05-28 13:39 ` Rudi Heitbaum
2022-05-29 2:48 ` Fox Chen
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