Am Wed, Feb 16, 2022 at 01:02:30AM +0100 schrieb Jason A. Donenfeld:
> Hardware random number generators are supposed to use the hw_random
> framework. This commit turns ath9k's kthread-based design into a proper
> hw_random driver.
>
> This compiles, but I have no hardware or other ability to determine
> whether it works. I'll leave further development up to the ath9k
> and hw_random maintainers.
>
> Cc: Toke Høiland-Jørgensen <toke@xxxxxxxxxx>
> Cc: Kalle Valo <kvalo@xxxxxxxxxx>
> Cc: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx>
> Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
> ---
> v2 operates on whole words when possible.
>
> drivers/net/wireless/ath/ath9k/ath9k.h | 2 +-
> drivers/net/wireless/ath/ath9k/rng.c | 72 +++++++++++---------------
> 2 files changed, 30 insertions(+), 44 deletions(-)
>
> diff --git a/drivers/net/wireless/ath/ath9k/ath9k.h b/drivers/net/wireless/ath/ath9k/ath9k.h
> index ef6f5ea06c1f..142f472903dc 100644
> --- a/drivers/net/wireless/ath/ath9k/ath9k.h
> +++ b/drivers/net/wireless/ath/ath9k/ath9k.h
> @@ -1072,7 +1072,7 @@ struct ath_softc {
>
> #ifdef CONFIG_ATH9K_HWRNG
> u32 rng_last;
> - struct task_struct *rng_task;
> + struct hwrng rng_ops;
> #endif
> };
>
> diff --git a/drivers/net/wireless/ath/ath9k/rng.c b/drivers/net/wireless/ath/ath9k/rng.c
> index aae2bd3cac69..a0a58f8e08d3 100644
> --- a/drivers/net/wireless/ath/ath9k/rng.c
> +++ b/drivers/net/wireless/ath/ath9k/rng.c
> @@ -22,11 +22,6 @@
> #include "hw.h"
> #include "ar9003_phy.h"
>
> -#define ATH9K_RNG_BUF_SIZE 320
> -#define ATH9K_RNG_ENTROPY(x) (((x) * 8 * 10) >> 5) /* quality: 10/32 */
> -
> -static DECLARE_WAIT_QUEUE_HEAD(rng_queue);
> -
> static int ath9k_rng_data_read(struct ath_softc *sc, u32 *buf, u32 buf_size)
> {
> int i, j;
> @@ -72,61 +67,52 @@ static u32 ath9k_rng_delay_get(u32 fail_stats)
> return delay;
> }
>
> -static int ath9k_rng_kthread(void *data)
> +static int ath9k_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
> {
> - int bytes_read;
> - struct ath_softc *sc = data;
> - u32 *rng_buf;
> - u32 delay, fail_stats = 0;
> -
> - rng_buf = kmalloc_array(ATH9K_RNG_BUF_SIZE, sizeof(u32), GFP_KERNEL);
> - if (!rng_buf)
> - goto out;
> -
> - while (!kthread_should_stop()) {
> - bytes_read = ath9k_rng_data_read(sc, rng_buf,
> - ATH9K_RNG_BUF_SIZE);
> - if (unlikely(!bytes_read)) {
> - delay = ath9k_rng_delay_get(++fail_stats);
> - wait_event_interruptible_timeout(rng_queue,
> - kthread_should_stop(),
> - msecs_to_jiffies(delay));
> - continue;
> - }
> -
> - fail_stats = 0;
> -
> - /* sleep until entropy bits under write_wakeup_threshold */
> - add_hwgenerator_randomness((void *)rng_buf, bytes_read,
> - ATH9K_RNG_ENTROPY(bytes_read));
> + struct ath_softc *sc = container_of(rng, struct ath_softc, rng_ops);
> + int bytes_read = 0;
> + u32 fail_stats = 0, word;
> +
> +retry:
> + if (max & ~3UL)
> + bytes_read = ath9k_rng_data_read(sc, buf, max >> 2);
> + if ((max & 3UL) && ath9k_rng_data_read(sc, &word, 1)) {
> + memcpy(buf + bytes_read, &word, max & 3);
> + bytes_read += max & 3;
> + memzero_explicit(&word, sizeof(word));
> + }
> + if (max && unlikely(!bytes_read) && wait) {
> + msleep(ath9k_rng_delay_get(++fail_stats));
> + goto retry;
> }
Potentially, this waits forever, if wait is set and no data is returned.
Instead, it should return to the main kthread loop every once in a while.
Thanks,
Dominik
