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From: "Reshetova, Elena" <elena.reshetova@intel.com>
To: Peter Zijlstra <peterz@infradead.org>
CC: David Windsor <dave@progbits.org>, Kees Cook <keescook@chromium.org>,
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        Alexei Starovoitov <alexei.starovoitov@gmail.com>,
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Subject: RE: [RFC][PATCH 2/7] kref: Add kref_read()
Thread-Topic: [RFC][PATCH 2/7] kref: Add kref_read()
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Date: Thu, 17 Nov 2016 15:42:02 +0000
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> Even if we now find all occurrences of atomic_t used as refcounter 
> (which we cannot actually guarantee in any case unless someone 
> manually reads every line) and convert it to refcount_t, we still have 
> atomic_t type present and new usage of it as refount will crawl in. It 
> is just a matter of time IMO.

>Improve tooling. The patterns shouldn't be _that_ hard to find. Once the tools are good, new code isn't a problem either.

>Anything: atomic*_{{dec,sub}_and_test,{add,sub}_return,fetch_{add,sub}}
>followed by a call_rcu()/free().

Does not find everything unfortunately. Even if you add to above atomic*_add_unless() and also things like schedule_work(), still I fear we aren't covering everything. 
What is worse, I don't think there is a mechanism to guarantee full coverage.