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    Subject[PATCH 5.17 481/772] hwrng: cn10k - Optimize cn10k_rng_read()
    Date
    From: Vladis Dronov <vdronov@redhat.com>

    [ Upstream commit 753d6770879894de10d74b437ab99ea380f1cad7 ]

    This function assumes that sizeof(void) is 1 and arithmetic works for
    void pointers. This is a GNU C extention and may not work with other
    compilers. Change this by using an u8 pointer.

    Also move cn10k_read_trng() out of a loop thus saving some cycles.

    Fixes: 38e9791a0209 ("hwrng: cn10k - Add random number generator support")
    Signed-off-by: Vladis Dronov <vdronov@redhat.com>
    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/char/hw_random/cn10k-rng.c | 16 ++++++++++------
    1 file changed, 10 insertions(+), 6 deletions(-)

    diff --git a/drivers/char/hw_random/cn10k-rng.c b/drivers/char/hw_random/cn10k-rng.c
    index 35001c63648b..dd226630b67d 100644
    --- a/drivers/char/hw_random/cn10k-rng.c
    +++ b/drivers/char/hw_random/cn10k-rng.c
    @@ -90,6 +90,7 @@ static int cn10k_rng_read(struct hwrng *hwrng, void *data,
    {
    struct cn10k_rng *rng = (struct cn10k_rng *)hwrng->priv;
    unsigned int size;
    + u8 *pos = data;
    int err = 0;
    u64 value;

    @@ -102,17 +103,20 @@ static int cn10k_rng_read(struct hwrng *hwrng, void *data,
    while (size >= 8) {
    cn10k_read_trng(rng, &value);

    - *((u64 *)data) = (u64)value;
    + *((u64 *)pos) = value;
    size -= 8;
    - data += 8;
    + pos += 8;
    }

    - while (size > 0) {
    + if (size > 0) {
    cn10k_read_trng(rng, &value);

    - *((u8 *)data) = (u8)value;
    - size--;
    - data++;
    + while (size > 0) {
    + *pos = (u8)value;
    + value >>= 8;
    + size--;
    + pos++;
    + }
    }

    return max - size;
    --
    2.35.1


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