tree b6584d4d94c400671a2c844c4637ee7f3fd78f47
parent 48b8583698d96d6290726400789fcd51c55691b1
author Tiago Pasqualini <tiago.pasqualini@canonical.com> 1725493950 -0300
committer Daniel P. Berrangé <berrange@redhat.com> 1725891218 +0100

crypto: run qcrypto_pbkdf2_count_iters in a new thread

CPU time accounting in the kernel has been demonstrated to have a
sawtooth pattern[1][2]. This can cause the getrusage system call to
not be as accurate as we are expecting, which can cause this calculation
to stall.

The kernel discussions shows that this inaccuracy happens when CPU time
gets big enough, so this patch changes qcrypto_pbkdf2_count_iters to run
in a fresh thread to avoid this inaccuracy. It also adds a sanity check
to fail the process if CPU time is not accounted.

[1] https://lore.kernel.org/lkml/159231011694.16989.16351419333851309713.tip-bot2@tip-bot2/
[2] https://lore.kernel.org/lkml/20221226031010.4079885-1-maxing.lan@bytedance.com/t/#m1c7f2fdc0ea742776a70fd1aa2a2e414c437f534

Resolves: #2398
Signed-off-by: Tiago Pasqualini <tiago.pasqualini@canonical.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>