* [PATCHv2 1/2] hwrng: optee: handle unlimited data rates @ 2020-07-23 8:46 Jorge Ramirez-Ortiz 2020-07-23 8:46 ` [PATCHv2 2/2] hwrng: optee: fix wait use case Jorge Ramirez-Ortiz 2020-07-24 13:24 ` [PATCHv2 1/2] hwrng: optee: handle unlimited data rates Sumit Garg 0 siblings, 2 replies; 14+ messages in thread From: Jorge Ramirez-Ortiz @ 2020-07-23 8:46 UTC (permalink / raw) To: jorge, sumit.garg, mpm, herbert Cc: jens.wiklander, arnd, ricardo, mike, gregkh, op-tee, linux-crypto, linux-kernel 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> --- 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 ^ permalink raw reply related [flat|nested] 14+ messages in thread
* [PATCHv2 2/2] hwrng: optee: fix wait use case 2020-07-23 8:46 [PATCHv2 1/2] hwrng: optee: handle unlimited data rates Jorge Ramirez-Ortiz @ 2020-07-23 8:46 ` Jorge Ramirez-Ortiz 2020-07-24 13:22 ` Sumit Garg 2020-08-05 13:34 ` Jorge Ramirez-Ortiz, Foundries 2020-07-24 13:24 ` [PATCHv2 1/2] hwrng: optee: handle unlimited data rates Sumit Garg 1 sibling, 2 replies; 14+ messages in thread From: Jorge Ramirez-Ortiz @ 2020-07-23 8:46 UTC (permalink / raw) To: jorge, sumit.garg, mpm, herbert Cc: jens.wiklander, arnd, ricardo, mike, gregkh, op-tee, linux-crypto, linux-kernel 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. Signed-off-by: Jorge Ramirez-Ortiz <jorge@foundries.io> --- 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)) return read; msleep((1000 * (max - read)) / pvt_data->data_rate); } else { -- 2.17.1 ^ permalink raw reply related [flat|nested] 14+ messages in thread
* Re: [PATCHv2 2/2] hwrng: optee: fix wait use case 2020-07-23 8:46 ` [PATCHv2 2/2] hwrng: optee: fix wait use case Jorge Ramirez-Ortiz @ 2020-07-24 13:22 ` Sumit Garg 2020-07-24 14:23 ` Jorge Ramirez-Ortiz, Foundries 2020-08-05 13:34 ` Jorge Ramirez-Ortiz, Foundries 1 sibling, 1 reply; 14+ messages in thread From: Sumit Garg @ 2020-07-24 13:22 UTC (permalink / raw) To: Jorge Ramirez-Ortiz Cc: Matt Mackall, Herbert Xu, Jens Wiklander, Arnd Bergmann, ricardo, Michael Scott, Greg Kroah-Hartman, op-tee, open list:HARDWARE RANDOM NUMBER GENERATOR CORE, Linux Kernel Mailing List On Thu, 23 Jul 2020 at 14:16, Jorge Ramirez-Ortiz <jorge@foundries.io> 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? > > Signed-off-by: Jorge Ramirez-Ortiz <jorge@foundries.io> > --- > 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 > ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCHv2 2/2] hwrng: optee: fix wait use case 2020-07-24 13:22 ` Sumit Garg @ 2020-07-24 14:23 ` Jorge Ramirez-Ortiz, Foundries 2020-07-28 10:05 ` Jorge Ramirez-Ortiz, Foundries 2020-08-05 13:49 ` Sumit Garg 0 siblings, 2 replies; 14+ messages in thread From: Jorge Ramirez-Ortiz, Foundries @ 2020-07-24 14:23 UTC (permalink / raw) To: Sumit Garg Cc: Jorge Ramirez-Ortiz, Matt Mackall, Herbert Xu, Jens Wiklander, Arnd Bergmann, ricardo, Michael Scott, Greg Kroah-Hartman, op-tee, open list:HARDWARE RANDOM NUMBER GENERATOR CORE, Linux Kernel Mailing List On 24/07/20, Sumit Garg wrote: > On Thu, 23 Jul 2020 at 14:16, Jorge Ramirez-Ortiz <jorge@foundries.io> 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? currently, if the user sets max 0, get_optee_rng_data will regardless issuese a call to the secure world requesting 0 bytes from the RNG with this patch, this request is avoided. > > > > > Signed-off-by: Jorge Ramirez-Ortiz <jorge@foundries.io> > > --- > > 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? no but I see no reason why there should be a wait since we already have all the data that we need; the msleep is only required when we need to wait for the RNG to generate entropy for the number of bytes we are requesting. if we are requesting 0 bytes, the entropy is already available. at leat this is what makes sense to me. > > -Sumit > > > return read; > > msleep((1000 * (max - read)) / pvt_data->data_rate); > > } else { > > -- > > 2.17.1 > > ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCHv2 2/2] hwrng: optee: fix wait use case 2020-07-24 14:23 ` Jorge Ramirez-Ortiz, Foundries @ 2020-07-28 10:05 ` Jorge Ramirez-Ortiz, Foundries 2020-08-05 13:49 ` Sumit Garg 1 sibling, 0 replies; 14+ messages in thread From: Jorge Ramirez-Ortiz, Foundries @ 2020-07-28 10:05 UTC (permalink / raw) To: Jorge Ramirez-Ortiz, Foundries Cc: Sumit Garg, Matt Mackall, Herbert Xu, Jens Wiklander, Arnd Bergmann, ricardo, Michael Scott, Greg Kroah-Hartman, op-tee, open list:HARDWARE RANDOM NUMBER GENERATOR CORE, Linux Kernel Mailing List On 24/07/20, Jorge Ramirez-Ortiz, Foundries wrote: > On 24/07/20, Sumit Garg wrote: > > On Thu, 23 Jul 2020 at 14:16, Jorge Ramirez-Ortiz <jorge@foundries.io> 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? > > currently, if the user sets max 0, get_optee_rng_data will regardless > issuese a call to the secure world requesting 0 bytes from the RNG > > with this patch, this request is avoided. > > > > > > > > > Signed-off-by: Jorge Ramirez-Ortiz <jorge@foundries.io> > > > --- > > > 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? > > no but I see no reason why there should be a wait since we already have > all the data that we need; the msleep is only required when we need to > wait for the RNG to generate entropy for the number of bytes we are > requesting. if we are requesting 0 bytes, the entropy is already > available. at leat this is what makes sense to me. > > any further comments? > > > > -Sumit > > > > > return read; > > > msleep((1000 * (max - read)) / pvt_data->data_rate); > > > } else { > > > -- > > > 2.17.1 > > > ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCHv2 2/2] hwrng: optee: fix wait use case 2020-07-24 14:23 ` Jorge Ramirez-Ortiz, Foundries 2020-07-28 10:05 ` Jorge Ramirez-Ortiz, Foundries @ 2020-08-05 13:49 ` Sumit Garg 2020-08-05 20:38 ` Jorge Ramirez-Ortiz, Foundries 1 sibling, 1 reply; 14+ messages in thread From: Sumit Garg @ 2020-08-05 13:49 UTC (permalink / raw) To: Jorge Ramirez-Ortiz, Foundries Cc: Matt Mackall, Herbert Xu, Jens Wiklander, Arnd Bergmann, ricardo, Michael Scott, Greg Kroah-Hartman, op-tee, open list:HARDWARE RANDOM NUMBER GENERATOR CORE, Linux Kernel Mailing List Apologies for my delayed response as I was busy with some other tasks along with holidays. On Fri, 24 Jul 2020 at 19:53, Jorge Ramirez-Ortiz, Foundries <jorge@foundries.io> wrote: > > On 24/07/20, Sumit Garg wrote: > > On Thu, 23 Jul 2020 at 14:16, Jorge Ramirez-Ortiz <jorge@foundries.io> 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? > > currently, if the user sets max 0, get_optee_rng_data will regardless > issuese a call to the secure world requesting 0 bytes from the RNG > This case is already handled by core API: rng_dev_read(). > with this patch, this request is avoided. > > > > > > > > > Signed-off-by: Jorge Ramirez-Ortiz <jorge@foundries.io> > > > --- > > > 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? > > no but I see no reason why there should be a wait since we already have > all the data that we need; the msleep is only required when we need to > wait for the RNG to generate entropy for the number of bytes we are > requesting. if we are requesting 0 bytes, the entropy is already > available. at leat this is what makes sense to me. > Wouldn't it lead to a call as msleep(0); that means no wait as well? -Sumit > > > > > -Sumit > > > > > return read; > > > msleep((1000 * (max - read)) / pvt_data->data_rate); > > > } else { > > > -- > > > 2.17.1 > > > ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCHv2 2/2] hwrng: optee: fix wait use case 2020-08-05 13:49 ` Sumit Garg @ 2020-08-05 20:38 ` Jorge Ramirez-Ortiz, Foundries 2020-08-06 6:11 ` Sumit Garg 0 siblings, 1 reply; 14+ messages in thread From: Jorge Ramirez-Ortiz, Foundries @ 2020-08-05 20:38 UTC (permalink / raw) To: Sumit Garg Cc: Jorge Ramirez-Ortiz, Foundries, Matt Mackall, Herbert Xu, Jens Wiklander, Arnd Bergmann, ricardo, Michael Scott, Greg Kroah-Hartman, op-tee, open list:HARDWARE RANDOM NUMBER GENERATOR CORE, Linux Kernel Mailing List On 05/08/20, Sumit Garg wrote: > Apologies for my delayed response as I was busy with some other tasks > along with holidays. no pb! was just making sure this wasnt falling through some cracks. > > On Fri, 24 Jul 2020 at 19:53, Jorge Ramirez-Ortiz, Foundries > <jorge@foundries.io> wrote: > > > > On 24/07/20, Sumit Garg wrote: > > > On Thu, 23 Jul 2020 at 14:16, Jorge Ramirez-Ortiz <jorge@foundries.io> 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? > > > > currently, if the user sets max 0, get_optee_rng_data will regardless > > issuese a call to the secure world requesting 0 bytes from the RNG > > > > This case is already handled by core API: rng_dev_read(). ah ok good point, you are right but yeah, there is no consequence to the actual patch. > > > with this patch, this request is avoided. > > > > > > > > > > > > > Signed-off-by: Jorge Ramirez-Ortiz <jorge@foundries.io> > > > > --- > > > > 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? > > > > no but I see no reason why there should be a wait since we already have > > all the data that we need; the msleep is only required when we need to > > wait for the RNG to generate entropy for the number of bytes we are > > requesting. if we are requesting 0 bytes, the entropy is already > > available. at leat this is what makes sense to me. > > > > Wouldn't it lead to a call as msleep(0); that means no wait as well? I dont understand: there is no reason to wait if read == max and this patch will not wait: if read == max it calls 'return read' am I misunderstanding your point? > > -Sumit > > > > > > > > > -Sumit > > > > > > > return read; > > > > msleep((1000 * (max - read)) / pvt_data->data_rate); > > > > } else { > > > > -- > > > > 2.17.1 > > > > ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCHv2 2/2] hwrng: optee: fix wait use case 2020-08-05 20:38 ` Jorge Ramirez-Ortiz, Foundries @ 2020-08-06 6:11 ` Sumit Garg 2020-08-06 6:30 ` Jorge Ramirez-Ortiz, Foundries 0 siblings, 1 reply; 14+ messages in thread From: Sumit Garg @ 2020-08-06 6:11 UTC (permalink / raw) To: Jorge Ramirez-Ortiz, Foundries Cc: Matt Mackall, Herbert Xu, Jens Wiklander, Arnd Bergmann, ricardo, Michael Scott, Greg Kroah-Hartman, op-tee, open list:HARDWARE RANDOM NUMBER GENERATOR CORE, Linux Kernel Mailing List On Thu, 6 Aug 2020 at 02:08, Jorge Ramirez-Ortiz, Foundries <jorge@foundries.io> wrote: > > On 05/08/20, Sumit Garg wrote: > > Apologies for my delayed response as I was busy with some other tasks > > along with holidays. > > no pb! was just making sure this wasnt falling through some cracks. > > > > > On Fri, 24 Jul 2020 at 19:53, Jorge Ramirez-Ortiz, Foundries > > <jorge@foundries.io> wrote: > > > > > > On 24/07/20, Sumit Garg wrote: > > > > On Thu, 23 Jul 2020 at 14:16, Jorge Ramirez-Ortiz <jorge@foundries.io> 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? > > > > > > currently, if the user sets max 0, get_optee_rng_data will regardless > > > issuese a call to the secure world requesting 0 bytes from the RNG > > > > > > > This case is already handled by core API: rng_dev_read(). > > ah ok good point, you are right > but yeah, there is no consequence to the actual patch. > So, at least you could get rid of the corresponding text from commit message. > > > > > with this patch, this request is avoided. > > > > > > > > > > > > > > > > > Signed-off-by: Jorge Ramirez-Ortiz <jorge@foundries.io> > > > > > --- > > > > > 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? > > > > > > no but I see no reason why there should be a wait since we already have > > > all the data that we need; the msleep is only required when we need to > > > wait for the RNG to generate entropy for the number of bytes we are > > > requesting. if we are requesting 0 bytes, the entropy is already > > > available. at leat this is what makes sense to me. > > > > > > > Wouldn't it lead to a call as msleep(0); that means no wait as well? > > I dont understand: there is no reason to wait if read == max and this > patch will not wait: if read == max it calls 'return read' > > am I misunderstanding your point? What I mean is that we shouldn't require this extra check here as there wasn't any wait if read == max with existing implementation too. -Sumit > > > > > -Sumit > > > > > > > > > > > > > -Sumit > > > > > > > > > return read; > > > > > msleep((1000 * (max - read)) / pvt_data->data_rate); > > > > > } else { > > > > > -- > > > > > 2.17.1 > > > > > ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCHv2 2/2] hwrng: optee: fix wait use case 2020-08-06 6:11 ` Sumit Garg @ 2020-08-06 6:30 ` Jorge Ramirez-Ortiz, Foundries 2020-08-06 6:57 ` Sumit Garg 0 siblings, 1 reply; 14+ messages in thread From: Jorge Ramirez-Ortiz, Foundries @ 2020-08-06 6:30 UTC (permalink / raw) To: Sumit Garg Cc: Jorge Ramirez-Ortiz, Foundries, Matt Mackall, Herbert Xu, Jens Wiklander, Arnd Bergmann, ricardo, Michael Scott, Greg Kroah-Hartman, op-tee, open list:HARDWARE RANDOM NUMBER GENERATOR CORE, Linux Kernel Mailing List On 06/08/20, Sumit Garg wrote: > On Thu, 6 Aug 2020 at 02:08, Jorge Ramirez-Ortiz, Foundries > <jorge@foundries.io> wrote: > > > > On 05/08/20, Sumit Garg wrote: > > > Apologies for my delayed response as I was busy with some other tasks > > > along with holidays. > > > > no pb! was just making sure this wasnt falling through some cracks. > > > > > > > > On Fri, 24 Jul 2020 at 19:53, Jorge Ramirez-Ortiz, Foundries > > > <jorge@foundries.io> wrote: > > > > > > > > On 24/07/20, Sumit Garg wrote: > > > > > On Thu, 23 Jul 2020 at 14:16, Jorge Ramirez-Ortiz <jorge@foundries.io> 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? > > > > > > > > currently, if the user sets max 0, get_optee_rng_data will regardless > > > > issuese a call to the secure world requesting 0 bytes from the RNG > > > > > > > > > > This case is already handled by core API: rng_dev_read(). > > > > ah ok good point, you are right > > but yeah, there is no consequence to the actual patch. > > > > So, at least you could get rid of the corresponding text from commit message. > > > > > > > > with this patch, this request is avoided. > > > > > > > > > > > > > > > > > > > > > Signed-off-by: Jorge Ramirez-Ortiz <jorge@foundries.io> > > > > > > --- > > > > > > 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? > > > > > > > > no but I see no reason why there should be a wait since we already have > > > > all the data that we need; the msleep is only required when we need to > > > > wait for the RNG to generate entropy for the number of bytes we are > > > > requesting. if we are requesting 0 bytes, the entropy is already > > > > available. at leat this is what makes sense to me. > > > > > > > > > > Wouldn't it lead to a call as msleep(0); that means no wait as well? > > > > I dont understand: there is no reason to wait if read == max and this > > patch will not wait: if read == max it calls 'return read' > > > > am I misunderstanding your point? > > What I mean is that we shouldn't require this extra check here as > there wasn't any wait if read == max with existing implementation too. um, I am getting confused Sumit with the exisiting implementation (the one we aim to replace), if get_optee_rng_data reads all the values requested on the first call (ie, read = 0) with wait set to true, the call will wait with msleep(0). Which is unnecessary and waits for a jiffy (ie, the call to msleep 0 will schedule a one jiffy timeout interrruptible) with this alternative implementation, msleep(0) does not get called. are we in synch? > > -Sumit > > > > > > > > > -Sumit > > > > > > > > > > > > > > > > > -Sumit > > > > > > > > > > > return read; > > > > > > msleep((1000 * (max - read)) / pvt_data->data_rate); > > > > > > } else { > > > > > > -- > > > > > > 2.17.1 > > > > > > ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCHv2 2/2] hwrng: optee: fix wait use case 2020-08-06 6:30 ` Jorge Ramirez-Ortiz, Foundries @ 2020-08-06 6:57 ` Sumit Garg 2020-08-06 8:14 ` Jorge Ramirez-Ortiz, Foundries 0 siblings, 1 reply; 14+ messages in thread From: Sumit Garg @ 2020-08-06 6:57 UTC (permalink / raw) To: Jorge Ramirez-Ortiz, Foundries Cc: Matt Mackall, Herbert Xu, Jens Wiklander, Arnd Bergmann, ricardo, Michael Scott, Greg Kroah-Hartman, op-tee, open list:HARDWARE RANDOM NUMBER GENERATOR CORE, Linux Kernel Mailing List On Thu, 6 Aug 2020 at 12:00, Jorge Ramirez-Ortiz, Foundries <jorge@foundries.io> wrote: > > On 06/08/20, Sumit Garg wrote: > > On Thu, 6 Aug 2020 at 02:08, Jorge Ramirez-Ortiz, Foundries > > <jorge@foundries.io> wrote: > > > > > > On 05/08/20, Sumit Garg wrote: > > > > Apologies for my delayed response as I was busy with some other tasks > > > > along with holidays. > > > > > > no pb! was just making sure this wasnt falling through some cracks. > > > > > > > > > > > On Fri, 24 Jul 2020 at 19:53, Jorge Ramirez-Ortiz, Foundries > > > > <jorge@foundries.io> wrote: > > > > > > > > > > On 24/07/20, Sumit Garg wrote: > > > > > > On Thu, 23 Jul 2020 at 14:16, Jorge Ramirez-Ortiz <jorge@foundries.io> 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? > > > > > > > > > > currently, if the user sets max 0, get_optee_rng_data will regardless > > > > > issuese a call to the secure world requesting 0 bytes from the RNG > > > > > > > > > > > > > This case is already handled by core API: rng_dev_read(). > > > > > > ah ok good point, you are right > > > but yeah, there is no consequence to the actual patch. > > > > > > > So, at least you could get rid of the corresponding text from commit message. > > > > > > > > > > > with this patch, this request is avoided. > > > > > > > > > > > > > > > > > > > > > > > > > Signed-off-by: Jorge Ramirez-Ortiz <jorge@foundries.io> > > > > > > > --- > > > > > > > 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? > > > > > > > > > > no but I see no reason why there should be a wait since we already have > > > > > all the data that we need; the msleep is only required when we need to > > > > > wait for the RNG to generate entropy for the number of bytes we are > > > > > requesting. if we are requesting 0 bytes, the entropy is already > > > > > available. at leat this is what makes sense to me. > > > > > > > > > > > > > Wouldn't it lead to a call as msleep(0); that means no wait as well? > > > > > > I dont understand: there is no reason to wait if read == max and this > > > patch will not wait: if read == max it calls 'return read' > > > > > > am I misunderstanding your point? > > > > What I mean is that we shouldn't require this extra check here as > > there wasn't any wait if read == max with existing implementation too. > > um, I am getting confused Sumit > > with the exisiting implementation (the one we aim to replace), if get_optee_rng_data reads all the values requested on the first call (ie, read = 0) with wait set to true, the call will wait with msleep(0). Which is unnecessary and waits for a jiffy (ie, the call to msleep 0 will schedule a one jiffy timeout interrruptible) > > with this alternative implementation, msleep(0) does not get called. > > are we in synch? Ah, I see msleep(0) also by default schedules timeout for 1 jiffy. So we are in sync now. Probably you can clarify this in commit message as well to avoid confusion. -Sumit > > > > > -Sumit > > > > > > > > > > > > > -Sumit > > > > > > > > > > > > > > > > > > > > > -Sumit > > > > > > > > > > > > > return read; > > > > > > > msleep((1000 * (max - read)) / pvt_data->data_rate); > > > > > > > } else { > > > > > > > -- > > > > > > > 2.17.1 > > > > > > > ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCHv2 2/2] hwrng: optee: fix wait use case 2020-08-06 6:57 ` Sumit Garg @ 2020-08-06 8:14 ` Jorge Ramirez-Ortiz, Foundries 2020-08-06 9:15 ` Sumit Garg 0 siblings, 1 reply; 14+ messages in thread From: Jorge Ramirez-Ortiz, Foundries @ 2020-08-06 8:14 UTC (permalink / raw) To: Sumit Garg Cc: Jorge Ramirez-Ortiz, Foundries, Matt Mackall, Herbert Xu, Jens Wiklander, Arnd Bergmann, ricardo, Michael Scott, Greg Kroah-Hartman, op-tee, open list:HARDWARE RANDOM NUMBER GENERATOR CORE, Linux Kernel Mailing List On 06/08/20, Sumit Garg wrote: > On Thu, 6 Aug 2020 at 12:00, Jorge Ramirez-Ortiz, Foundries > <jorge@foundries.io> wrote: > > > > On 06/08/20, Sumit Garg wrote: > > > On Thu, 6 Aug 2020 at 02:08, Jorge Ramirez-Ortiz, Foundries > > > <jorge@foundries.io> wrote: > > > > > > > > On 05/08/20, Sumit Garg wrote: > > > > > Apologies for my delayed response as I was busy with some other tasks > > > > > along with holidays. > > > > > > > > no pb! was just making sure this wasnt falling through some cracks. > > > > > > > > > > > > > > On Fri, 24 Jul 2020 at 19:53, Jorge Ramirez-Ortiz, Foundries > > > > > <jorge@foundries.io> wrote: > > > > > > > > > > > > On 24/07/20, Sumit Garg wrote: > > > > > > > On Thu, 23 Jul 2020 at 14:16, Jorge Ramirez-Ortiz <jorge@foundries.io> 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? > > > > > > > > > > > > currently, if the user sets max 0, get_optee_rng_data will regardless > > > > > > issuese a call to the secure world requesting 0 bytes from the RNG > > > > > > > > > > > > > > > > This case is already handled by core API: rng_dev_read(). > > > > > > > > ah ok good point, you are right > > > > but yeah, there is no consequence to the actual patch. > > > > > > > > > > So, at least you could get rid of the corresponding text from commit message. > > > > > > > > > > > > > > with this patch, this request is avoided. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Signed-off-by: Jorge Ramirez-Ortiz <jorge@foundries.io> > > > > > > > > --- > > > > > > > > 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? > > > > > > > > > > > > no but I see no reason why there should be a wait since we already have > > > > > > all the data that we need; the msleep is only required when we need to > > > > > > wait for the RNG to generate entropy for the number of bytes we are > > > > > > requesting. if we are requesting 0 bytes, the entropy is already > > > > > > available. at leat this is what makes sense to me. > > > > > > > > > > > > > > > > Wouldn't it lead to a call as msleep(0); that means no wait as well? > > > > > > > > I dont understand: there is no reason to wait if read == max and this > > > > patch will not wait: if read == max it calls 'return read' > > > > > > > > am I misunderstanding your point? > > > > > > What I mean is that we shouldn't require this extra check here as > > > there wasn't any wait if read == max with existing implementation too. > > > > um, I am getting confused Sumit > > > > with the exisiting implementation (the one we aim to replace), if get_optee_rng_data reads all the values requested on the first call (ie, read = 0) with wait set to true, the call will wait with msleep(0). Which is unnecessary and waits for a jiffy (ie, the call to msleep 0 will schedule a one jiffy timeout interrruptible) > > > > with this alternative implementation, msleep(0) does not get called. > > > > are we in synch? > > Ah, I see msleep(0) also by default schedules timeout for 1 jiffy. So > we are in sync now. Probably you can clarify this in commit message as > well to avoid confusion. ok will do. shall I add your reviewed-by line or just resend? > > -Sumit > > > > > > > > > -Sumit > > > > > > > > > > > > > > > > > -Sumit > > > > > > > > > > > > > > > > > > > > > > > > > -Sumit > > > > > > > > > > > > > > > return read; > > > > > > > > msleep((1000 * (max - read)) / pvt_data->data_rate); > > > > > > > > } else { > > > > > > > > -- > > > > > > > > 2.17.1 > > > > > > > > ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCHv2 2/2] hwrng: optee: fix wait use case 2020-08-06 8:14 ` Jorge Ramirez-Ortiz, Foundries @ 2020-08-06 9:15 ` Sumit Garg 0 siblings, 0 replies; 14+ messages in thread From: Sumit Garg @ 2020-08-06 9:15 UTC (permalink / raw) To: Jorge Ramirez-Ortiz, Foundries Cc: Matt Mackall, Herbert Xu, Jens Wiklander, Arnd Bergmann, ricardo, Michael Scott, Greg Kroah-Hartman, op-tee, open list:HARDWARE RANDOM NUMBER GENERATOR CORE, Linux Kernel Mailing List On Thu, 6 Aug 2020 at 13:44, Jorge Ramirez-Ortiz, Foundries <jorge@foundries.io> wrote: > > On 06/08/20, Sumit Garg wrote: > > On Thu, 6 Aug 2020 at 12:00, Jorge Ramirez-Ortiz, Foundries > > <jorge@foundries.io> wrote: > > > > > > On 06/08/20, Sumit Garg wrote: > > > > On Thu, 6 Aug 2020 at 02:08, Jorge Ramirez-Ortiz, Foundries > > > > <jorge@foundries.io> wrote: > > > > > > > > > > On 05/08/20, Sumit Garg wrote: > > > > > > Apologies for my delayed response as I was busy with some other tasks > > > > > > along with holidays. > > > > > > > > > > no pb! was just making sure this wasnt falling through some cracks. > > > > > > > > > > > > > > > > > On Fri, 24 Jul 2020 at 19:53, Jorge Ramirez-Ortiz, Foundries > > > > > > <jorge@foundries.io> wrote: > > > > > > > > > > > > > > On 24/07/20, Sumit Garg wrote: > > > > > > > > On Thu, 23 Jul 2020 at 14:16, Jorge Ramirez-Ortiz <jorge@foundries.io> 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? > > > > > > > > > > > > > > currently, if the user sets max 0, get_optee_rng_data will regardless > > > > > > > issuese a call to the secure world requesting 0 bytes from the RNG > > > > > > > > > > > > > > > > > > > This case is already handled by core API: rng_dev_read(). > > > > > > > > > > ah ok good point, you are right > > > > > but yeah, there is no consequence to the actual patch. > > > > > > > > > > > > > So, at least you could get rid of the corresponding text from commit message. > > > > > > > > > > > > > > > > > with this patch, this request is avoided. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Signed-off-by: Jorge Ramirez-Ortiz <jorge@foundries.io> > > > > > > > > > --- > > > > > > > > > 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? > > > > > > > > > > > > > > no but I see no reason why there should be a wait since we already have > > > > > > > all the data that we need; the msleep is only required when we need to > > > > > > > wait for the RNG to generate entropy for the number of bytes we are > > > > > > > requesting. if we are requesting 0 bytes, the entropy is already > > > > > > > available. at leat this is what makes sense to me. > > > > > > > > > > > > > > > > > > > Wouldn't it lead to a call as msleep(0); that means no wait as well? > > > > > > > > > > I dont understand: there is no reason to wait if read == max and this > > > > > patch will not wait: if read == max it calls 'return read' > > > > > > > > > > am I misunderstanding your point? > > > > > > > > What I mean is that we shouldn't require this extra check here as > > > > there wasn't any wait if read == max with existing implementation too. > > > > > > um, I am getting confused Sumit > > > > > > with the exisiting implementation (the one we aim to replace), if get_optee_rng_data reads all the values requested on the first call (ie, read = 0) with wait set to true, the call will wait with msleep(0). Which is unnecessary and waits for a jiffy (ie, the call to msleep 0 will schedule a one jiffy timeout interrruptible) > > > > > > with this alternative implementation, msleep(0) does not get called. > > > > > > are we in synch? > > > > Ah, I see msleep(0) also by default schedules timeout for 1 jiffy. So > > we are in sync now. Probably you can clarify this in commit message as > > well to avoid confusion. > > ok will do. > shall I add your reviewed-by line or just resend? > Yes it's fine with me to add mine reviewed-by. > > > > -Sumit > > > > > > > > > > > > > -Sumit > > > > > > > > > > > > > > > > > > > > > -Sumit > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -Sumit > > > > > > > > > > > > > > > > > return read; > > > > > > > > > msleep((1000 * (max - read)) / pvt_data->data_rate); > > > > > > > > > } else { > > > > > > > > > -- > > > > > > > > > 2.17.1 > > > > > > > > > ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCHv2 2/2] hwrng: optee: fix wait use case 2020-07-23 8:46 ` [PATCHv2 2/2] hwrng: optee: fix wait use case Jorge Ramirez-Ortiz 2020-07-24 13:22 ` Sumit Garg @ 2020-08-05 13:34 ` Jorge Ramirez-Ortiz, Foundries 1 sibling, 0 replies; 14+ messages in thread From: Jorge Ramirez-Ortiz, Foundries @ 2020-08-05 13:34 UTC (permalink / raw) To: Jorge Ramirez-Ortiz Cc: sumit.garg, mpm, herbert, jens.wiklander, arnd, ricardo, mike, gregkh, op-tee, linux-crypto, linux-kernel On 23/07/20, Jorge Ramirez-Ortiz 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. > > Signed-off-by: Jorge Ramirez-Ortiz <jorge@foundries.io> > --- > 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)) > return read; > msleep((1000 * (max - read)) / pvt_data->data_rate); > } else { any comments please? ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [PATCHv2 1/2] hwrng: optee: handle unlimited data rates 2020-07-23 8:46 [PATCHv2 1/2] hwrng: optee: handle unlimited data rates Jorge Ramirez-Ortiz 2020-07-23 8:46 ` [PATCHv2 2/2] hwrng: optee: fix wait use case Jorge Ramirez-Ortiz @ 2020-07-24 13:24 ` Sumit Garg 1 sibling, 0 replies; 14+ messages in thread From: Sumit Garg @ 2020-07-24 13:24 UTC (permalink / raw) To: Jorge Ramirez-Ortiz Cc: Matt Mackall, Herbert Xu, Jens Wiklander, Arnd Bergmann, ricardo, Michael Scott, Greg Kroah-Hartman, op-tee, open list:HARDWARE RANDOM NUMBER GENERATOR CORE, Linux Kernel Mailing List On Thu, 23 Jul 2020 at 14:16, Jorge Ramirez-Ortiz <jorge@foundries.io> 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> > --- > drivers/char/hw_random/optee-rng.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > Sounds good to me. FWIW: Reviewed-by: Sumit Garg <sumit.garg@linaro.org> -Sumit > 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 > ^ permalink raw reply [flat|nested] 14+ messages in thread
end of thread, other threads:[~2020-08-06 11:13 UTC | newest] Thread overview: 14+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2020-07-23 8:46 [PATCHv2 1/2] hwrng: optee: handle unlimited data rates Jorge Ramirez-Ortiz 2020-07-23 8:46 ` [PATCHv2 2/2] hwrng: optee: fix wait use case Jorge Ramirez-Ortiz 2020-07-24 13:22 ` Sumit Garg 2020-07-24 14:23 ` Jorge Ramirez-Ortiz, Foundries 2020-07-28 10:05 ` Jorge Ramirez-Ortiz, Foundries 2020-08-05 13:49 ` Sumit Garg 2020-08-05 20:38 ` Jorge Ramirez-Ortiz, Foundries 2020-08-06 6:11 ` Sumit Garg 2020-08-06 6:30 ` Jorge Ramirez-Ortiz, Foundries 2020-08-06 6:57 ` Sumit Garg 2020-08-06 8:14 ` Jorge Ramirez-Ortiz, Foundries 2020-08-06 9:15 ` Sumit Garg 2020-08-05 13:34 ` Jorge Ramirez-Ortiz, Foundries 2020-07-24 13:24 ` [PATCHv2 1/2] hwrng: optee: handle unlimited data rates Sumit Garg
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