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Subject: Re: [PATCH 00/11] Introduce Simple atomic and non-atomic counters
To:     Kees Cook <keescook@chromium.org>
Cc:     corbet@lwn.net, gregkh@linuxfoundation.org, shuah@kernel.org,
        rafael@kernel.org, johannes@sipsolutions.net, lenb@kernel.org,
        james.morse@arm.com, tony.luck@intel.com, bp@alien8.de,
        arve@android.com, tkjos@android.com, maco@android.com,
        joel@joelfernandes.org, christian@brauner.io, hridya@google.com,
        surenb@google.com, minyard@acm.org, arnd@arndb.de,
        mchehab@kernel.org, rric@kernel.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
        linux-acpi@vger.kernel.org, devel@driverdev.osuosl.org,
        openipmi-developer@lists.sourceforge.net,
        linux-edac@vger.kernel.org, Shuah Khan <skhan@linuxfoundation.org>
References: <cover.1601073127.git.skhan@linuxfoundation.org>
 <202009251650.193E2AD@keescook>
From:   Shuah Khan <skhan@linuxfoundation.org>
Message-ID: <7d8f86ab-4333-afa1-6523-e42ae5c7d9b2@linuxfoundation.org>
Date:   Fri, 25 Sep 2020 18:13:37 -0600
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On 9/25/20 5:52 PM, Kees Cook wrote:
> On Fri, Sep 25, 2020 at 05:47:14PM -0600, Shuah Khan wrote:
>> -- Addressed Kees's comments:
>>     1. Non-atomic counters renamed to counter_simple32 and counter_simple64
>>        to clearly indicate size.
>>     2. Added warning for counter_simple* usage and it should be used only
>>        when there is no need for atomicity.
>>     3. Renamed counter_atomic to counter_atomic32 to clearly indicate size.
>>     4. Renamed counter_atomic_long to counter_atomic64 and it now uses
>>        atomic64_t ops and indicates size.
>>     5. Test updated for the API renames.
>>     6. Added helper functions for test results printing
>>     7. Verified that the test module compiles in kunit env. and test
>>        module can be loaded to run the test.
> 
> Thanks for all of this!
> 
>>     8. Updated Documentation to reflect the intent to make the API
>>        restricted so it can never be used to guard object lifetimes
>>        and state management. I left _return ops for now, inc_return
>>        is necessary for now as per the discussion we had on this topic.
> 
> I still *really* do not want dec_return() to exist. That is asking for
> trouble. I'd prefer inc_return() not exist either, but I can live with
> it. ;)
> 

Thanks. I am equally concerned about adding anything that can be used to
guard object lifetimes. So I will make sure this set won't expand and
plan to remove dec_return() if we don't find any usages.

thanks,
-- Shuah