linux-kernel - Re: [PATCH v3 01/11] counters: Introduce counter

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Message-ID: <20201009194904.GB1073957@hirez.programming.kicks-ass.net>
Date:   Fri, 9 Oct 2020 21:49:04 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Shuah Khan <skhan@...uxfoundation.org>
Cc:     corbet@....net, keescook@...omium.org, gregkh@...uxfoundation.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 01/11] counters: Introduce counter_atomic* counters

On Fri, Oct 09, 2020 at 09:55:56AM -0600, Shuah Khan wrote:
> Introduce Simple atomic counters.
> 
> There are a number of atomic_t usages in the kernel where atomic_t api
> is used strictly for counting and not for managing object lifetime. In
> some cases, atomic_t might not even be needed.
> 
> The purpose of these counters is to clearly differentiate atomic_t
> counters from atomic_t usages that guard object lifetimes, hence prone
> to overflow and underflow errors. It allows tools that scan for underflow
> and overflow on atomic_t usages to detect overflow and underflows to scan
> just the cases that are prone to errors.

Under- and overflow on atomic_t is perfectly fine. We're not going to
create pointless wrappers for this.

What tools, and how could they not be served by adding annotations to
variable declarations?