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Date:   Mon, 14 Nov 2022 17:13:51 +0000
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Subject: Re: [PATCH v3 1/3] jump_label: Prevent key->enabled int overflow
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To:     Jason Baron <jbaron@akamai.com>, Dmitry Safonov <dima@arista.com>,
        linux-kernel@vger.kernel.org, David Ahern <dsahern@kernel.org>,
        Eric Dumazet <edumazet@google.com>
Cc:     Bob Gilligan <gilligan@arista.com>,
        "David S. Miller" <davem@davemloft.net>,
        Francesco Ruggeri <fruggeri@arista.com>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Salam Noureddine <noureddine@arista.com>,
        netdev@vger.kernel.org, Ard Biesheuvel <ardb@kernel.org>,
        Josh Poimboeuf <jpoimboe@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Steven Rostedt <rostedt@goodmis.org>
References: <20221111212320.1386566-1-dima@arista.com>
 <20221111212320.1386566-2-dima@arista.com>
 <ae9e4333-7070-d550-c0b5-f4d122d2f025@akamai.com>
From:   Dmitry Safonov <0x7f454c46@gmail.com>
In-Reply-To: <ae9e4333-7070-d550-c0b5-f4d122d2f025@akamai.com>
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On 11/14/22 16:24, Jason Baron wrote:
> 
[..]
>> @@ -148,16 +167,23 @@ void static_key_slow_inc_cpuslocked(struct static_key *key)
>>  		 */
>>  		atomic_set_release(&key->enabled, 1);
>>  	} else {
>> -		atomic_inc(&key->enabled);
>> +		if (WARN_ON_ONCE(static_key_fast_inc(key))) {
> 
> Shouldn't that be negated to catch the overflow:
> 
> if (WARN_ON_ONCE(!static_key_fast_inc(key)))

Oh, that's just embarrassing!
I wonder how did I miss it during tests..

Thanks for spotting this, will fix in v4,
            Dmitry