From c0f6eebedddaa4ab97311ec0730ab174d2a4c0bb Mon Sep 17 00:00:00 2001 From: Jorge Ramirez-Ortiz Date: Thu, 6 Aug 2020 12:00:10 +0200 Subject: [PATCH] hwrng: optee - fix wait use case The current code waits for data to be available before attempting a second read. However the second read would not be executed as the while loop will exit. This fix does not wait if all data has been read (skips the call to msleep(0)) and reads a second time if partial data was retrieved on the first read. Worth noticing that since msleep(0) schedules a one jiffy timeout is better to skip such a call. Signed-off-by: Jorge Ramirez-Ortiz Reviewed-by: Sumit Garg Signed-off-by: Herbert Xu --- drivers/char/hw_random/optee-rng.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/char/hw_random/optee-rng.c b/drivers/char/hw_random/optee-rng.c index 5bc4700c4dae1..a99d829499818 100644 --- a/drivers/char/hw_random/optee-rng.c +++ b/drivers/char/hw_random/optee-rng.c @@ -122,14 +122,14 @@ static int optee_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait) if (max > MAX_ENTROPY_REQ_SZ) max = MAX_ENTROPY_REQ_SZ; - while (read == 0) { + while (read < max) { rng_size = get_optee_rng_data(pvt_data, data, (max - read)); data += rng_size; read += rng_size; if (wait && pvt_data->data_rate) { - if (timeout-- == 0) + if ((timeout-- == 0) || (read == max)) return read; msleep((1000 * (max - read)) / pvt_data->data_rate); } else { -- 2.30.2