On 2/16/22, Toke Høiland-Jørgensen [off-list ref] wrote:

"Jason A. Donenfeld" [off-list ref] writes:

quoted

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 <redacted>
Cc: Kalle Valo <kvalo@kernel.org>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 drivers/net/wireless/ath/ath9k/ath9k.h |  2 +-
 drivers/net/wireless/ath/ath9k/rng.c   | 62 +++++++++-----------------
 2 files changed, 23 insertions(+), 41 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..369b222908ba 100644

--- a/drivers/net/wireless/ath/ath9k/rng.c
+++ b/drivers/net/wireless/ath/ath9k/rng.c

@@ -22,9 +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 */

So this comment says "quality: 10/32" but below you're setting "quality"
as 320. No idea what the units are supposed to be, but is this right?

I think the unit is supposed to be how many entropic bits there are
out of 1024 bits? These types of estimates are always BS, so keeping
it on the lower end as before seemed right. Herbert can jump in here
if he has a better idea; that's his jig.

quoted

 static DECLARE_WAIT_QUEUE_HEAD(rng_queue);

 static int ath9k_rng_data_read(struct ath_softc *sc, u32 *buf, u32
buf_size)

This function takes buf as a *u32, and interprets buf_size as a number
of u32s...

Oh my... Nice catch. I'll send a v2 shortly. I wonder how this managed
to work for Rui.

quoted

@@ -72,61 +69,46 @@ 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)
 {
+	struct ath_softc *sc = container_of(rng, struct ath_softc, rng_ops);
 	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));
-	}
+	u32 fail_stats = 0;

-	kfree(rng_buf);
-out:
-	sc->rng_task = NULL;
+retry:
+	bytes_read = ath9k_rng_data_read(sc, buf, max);

... but AFAICT here you're calling it with a buffer size from hw_random
that's in bytes?

V2 on its way. Rui - you may need to re-test...

Jason