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Subject: Re: SLAB_TYPESAFE_BY_RCU without constructors (was Re: [PATCH v4
 13/17] khwasan: add hooks implementation)
To:     Dmitry Vyukov <dvyukov@google.com>,
        Eric Dumazet <eric.dumazet@gmail.com>
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From:   Eric Dumazet <eric.dumazet@gmail.com>
Message-ID: <cf751136-c459-853a-0210-abf16f54ad17@gmail.com>
Date:   Wed, 1 Aug 2018 04:28:47 -0700
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On 08/01/2018 03:34 AM, Dmitry Vyukov wrote:
> On Wed, Aug 1, 2018 at 12:23 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
>> On 08/01/2018 02:03 AM, Andrey Ryabinin wrote:
>>
>>> I can't think of any advantage in not having the constructor.
>>
>> I can't see any advantage adding another indirect call,
>> in RETPOLINE world.
> 
> Can you please elaborate what's the problem here?
> If slab ctor call have RETPOLINE, then using ctors more does not
> introduce any security problems and they are not _that_ slow.

They _are_ slow, when we have dozens of them in a code path.

I object "having to add" yet another indirect call, if this can be avoided [*]

If some people want to use ctor, fine, but do not request this.

[*] This can be tricky, but worth the pain.