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@foundries.io Reviewed-by: Sumit Garg sumit.garg@linaro.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);
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 jorge@foundries.io Reviewed-by: Sumit Garg sumit.garg@linaro.org --- 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)) return read; msleep((1000 * (max - read)) / pvt_data->data_rate); } else {
On Thu, Aug 06, 2020 at 12:00:09PM +0200, Jorge Ramirez-Ortiz wrote:
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@foundries.io Reviewed-by: Sumit Garg sumit.garg@linaro.org
drivers/char/hw_random/optee-rng.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
All applied. Thanks.
op-tee@lists.trustedfirmware.org
-
Herbert Xu -
Jorge Ramirez-Ortiz