Re: [PATCHv2 2/2] hwrng: optee: fix wait use case
From: Sumit Garg <hidden>
Date: 2020-07-24 13:22:26
Also in:
lkml, op-tee
On Thu, 23 Jul 2020 at 14:16, Jorge Ramirez-Ortiz [off-list ref] wrote:
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 exits. This fix does not wait if all data has been read and reads a second time if only partial data was retrieved on the first read. This fix also does not attempt to read if not data is requested.
I am not sure how this is possible, can you elaborate?
quoted hunk ↗ jump to hunk
Signed-off-by: Jorge Ramirez-Ortiz <redacted> --- v2: tidy up the while loop to avoid reading when no data is requested 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 5bc4700c4dae..a99d82949981 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))
If read == max, would there be any sleep? -Sumit
return read;
msleep((1000 * (max - read)) / pvt_data->data_rate);
} else {
--
2.17.1