From: Sean Christopherson <seanjc@google.com>
To: Colton Lewis <coltonlewis@google.com>
Cc: kvm@vger.kernel.org, pbonzini@redhat.com, maz@kernel.org,
dmatlack@google.com, oupton@google.com, ricarkol@google.com,
andrew.jones@linux.dev
Subject: Re: [PATCH v6 3/3] KVM: selftests: randomize page access order
Date: Tue, 11 Oct 2022 18:22:15 +0000 [thread overview]
Message-ID: <Y0W0V5hsTkKLg59D@google.com> (raw)
In-Reply-To: <gsntedve2pqz.fsf@coltonlewis-kvm.c.googlers.com>
On Tue, Oct 11, 2022, Colton Lewis wrote:
> Sean Christopherson <seanjc@google.com> writes:
> > Ya, I'm trippling (quadrupling?) down on my suggestion to improve the
> > APIs. Users
> > should not be able to screw up like this, i.e. shouldn't need comments
> > to warn
> > readers, and adding another call to get a random number shouldn't affect
> > unrelated
> > code.
>
> Previous calls to PRNGs always affect later calls to PRNGs. That's how
> they work.
Ya, that's not the type of bugs I'm worried about.
> This "screw up" would be equally likely with any API because the caller
> always needs to decide if they should reuse the same random number or need a
> new one.
I disagree, the in/out parameter _requires_ the calling code to store the random
number in a variable. Returning the random number allows consuming the number
without needing an intermediate variable, e.g.
if (random_bool())
<do stuff>
which makes it easy to avoid an entire class of bugs.
next prev parent reply other threads:[~2022-10-11 18:24 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-12 19:58 [PATCH v6 0/3] KVM: selftests: randomize memory access of dirty_log_perf_test Colton Lewis
2022-09-12 19:58 ` [PATCH v6 1/3] KVM: selftests: implement random number generation for guest code Colton Lewis
2022-10-07 20:41 ` Sean Christopherson
2022-10-11 18:11 ` Colton Lewis
2022-10-11 18:39 ` Sean Christopherson
2022-10-11 22:24 ` Colton Lewis
2022-10-11 23:47 ` Sean Christopherson
2022-10-12 21:11 ` Colton Lewis
2022-10-12 23:34 ` Sean Christopherson
2022-10-10 18:03 ` Sean Christopherson
2022-10-11 18:13 ` Colton Lewis
2022-10-11 18:26 ` Sean Christopherson
2022-10-11 22:33 ` Colton Lewis
2022-09-12 19:58 ` [PATCH v6 2/3] KVM: selftests: randomize which pages are written vs read Colton Lewis
2022-10-07 20:55 ` Sean Christopherson
2022-10-07 21:07 ` David Matlack
2022-10-08 9:50 ` Andrew Jones
2022-10-10 14:46 ` Sean Christopherson
2022-10-10 16:38 ` Andrew Jones
2022-09-12 19:58 ` [PATCH v6 3/3] KVM: selftests: randomize page access order Colton Lewis
2022-10-07 21:09 ` Sean Christopherson
2022-10-11 18:12 ` Colton Lewis
2022-10-11 18:22 ` Sean Christopherson [this message]
2022-10-11 22:25 ` Colton Lewis
2022-10-11 22:50 ` Sean Christopherson
2022-09-19 22:36 ` [PATCH v6 0/3] KVM: selftests: randomize memory access of dirty_log_perf_test David Matlack
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