linux-kernel - [PATCHv3 1/2] hwrng: optee: handle unlimited data rates

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Date:   Thu,  6 Aug 2020 12:00:09 +0200
From:   Jorge Ramirez-Ortiz <jorge@...ndries.io>
To:     jorge@...ndries.io, sumit.garg@...aro.org,
        jens.wiklander@...aro.org
Cc:     mpm@...enic.com, herbert@...dor.apana.org.au, arnd@...db.de,
        ricardo@...ndries.io, mike@...ndries.io,
        gregkh@...uxfoundation.org, op-tee@...ts.trustedfirmware.org,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCHv3 1/2] hwrng: optee: handle unlimited data rates

Data rates of MAX_UINT32 will schedule an unnecessary one jiffy
timeout on the call to msleep. Avoid this scenario by using 0 as the
unlimited data rate.

Signed-off-by: Jorge Ramirez-Ortiz <jorge@...ndries.io>
Reviewed-by: Sumit Garg <sumit.garg@...aro.org>
---
 drivers/char/hw_random/optee-rng.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/char/hw_random/optee-rng.c b/drivers/char/hw_random/optee-rng.c
index 49b2e02537dd..5bc4700c4dae 100644
--- a/drivers/char/hw_random/optee-rng.c
+++ b/drivers/char/hw_random/optee-rng.c
@@ -128,7 +128,7 @@ static int optee_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
 		data += rng_size;
 		read += rng_size;
 
-		if (wait) {
+		if (wait && pvt_data->data_rate) {
 			if (timeout-- == 0)
 				return read;
 			msleep((1000 * (max - read)) / pvt_data->data_rate);
-- 
2.17.1