ACK: [SRU][Bionic][PATCH 0/1] s390/archrandom: Rework arch random implementation.

[Khaled Elmously]

On 2018-06-13 12:04:03 , Joseph Salisbury wrote:
> BugLink: http://bugs.launchpad.net/bugs/1775391
> 
> == SRU Justification ==
> IBM reports that arch_get_random_seed_long() invocations may slow down the 
> interrupt handling on heavy interrupt producing loads.
> 
> The existing random device driver calls arch_get_random_seed_long() in 
> interrupt context. The current implementation of this function uses the 
> PRNO(TRNG) instruction to provide good entropy. This instruction is 
> relatively slow and expensive and may slow down the capacity of interrupts which can be handled per cpu.
> 
> This fix reworks the arch_get_random_seed implementation.  It introduces a 
> buffer concept to decouple the delivery of random data via 
> arch_get_random_seed*() from the generation of new random bytes and so 
> does not limit the interrupt handling per cpu any more.
> 
> == Fix ==
> 966f53e750ae ("s390/archrandom: Rework arch random implementation.")
> 
> == Regression Potential ==
> Low.  This fix is limited to s390.
> 
> == Test Case ==
> Verified upfront by IBM during upstream integration
> 
> Harald Freudenberger (1):
>   s390/archrandom: Rework arch random implementation.
> 
>  arch/s390/crypto/arch_random.c     | 103 +++++++++++++++++++++++++++++++++++--
>  arch/s390/include/asm/archrandom.h |  13 ++---
>  2 files changed, 102 insertions(+), 14 deletions(-)
> 

Acked-by: Khalid Elmously <khalid.elmously at canonical.com>