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    Subject[PATCH 5.10 447/452] Revert "random: use static branch for crng_ready()"
    Date
    From: "Jason A. Donenfeld" <Jason@zx2c4.com>

    This reverts upstream commit f5bda35fba615ace70a656d4700423fa6c9bebee
    from stable. It's not essential and will take some time during 5.19 to
    work out properly.

    Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
    ---
    drivers/char/random.c | 12 ++----------
    1 file changed, 2 insertions(+), 10 deletions(-)

    --- a/drivers/char/random.c
    +++ b/drivers/char/random.c
    @@ -79,8 +79,7 @@ static enum {
    CRNG_EARLY = 1, /* At least POOL_EARLY_BITS collected */
    CRNG_READY = 2 /* Fully initialized with POOL_READY_BITS collected */
    } crng_init __read_mostly = CRNG_EMPTY;
    -static DEFINE_STATIC_KEY_FALSE(crng_is_ready);
    -#define crng_ready() (static_branch_likely(&crng_is_ready) || crng_init >= CRNG_READY)
    +#define crng_ready() (likely(crng_init >= CRNG_READY))
    /* Various types of waiters for crng_init->CRNG_READY transition. */
    static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait);
    static struct fasync_struct *fasync;
    @@ -110,11 +109,6 @@ bool rng_is_initialized(void)
    }
    EXPORT_SYMBOL(rng_is_initialized);

    -static void __cold crng_set_ready(struct work_struct *work)
    -{
    - static_branch_enable(&crng_is_ready);
    -}
    -
    /* Used by wait_for_random_bytes(), and considered an entropy collector, below. */
    static void try_to_generate_entropy(void);

    @@ -268,7 +262,7 @@ static void crng_reseed(void)
    ++next_gen;
    WRITE_ONCE(base_crng.generation, next_gen);
    WRITE_ONCE(base_crng.birth, jiffies);
    - if (!static_branch_likely(&crng_is_ready))
    + if (!crng_ready())
    crng_init = CRNG_READY;
    spin_unlock_irqrestore(&base_crng.lock, flags);
    memzero_explicit(key, sizeof(key));
    @@ -711,7 +705,6 @@ static void extract_entropy(void *buf, s

    static void __cold _credit_init_bits(size_t bits)
    {
    - static struct execute_work set_ready;
    unsigned int new, orig, add;
    unsigned long flags;

    @@ -727,7 +720,6 @@ static void __cold _credit_init_bits(siz

    if (orig < POOL_READY_BITS && new >= POOL_READY_BITS) {
    crng_reseed(); /* Sets crng_init to CRNG_READY under base_crng.lock. */
    - execute_in_process_context(crng_set_ready, &set_ready);
    process_random_ready_list();
    wake_up_interruptible(&crng_init_wait);
    kill_fasync(&fasync, SIGIO, POLL_IN);

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