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([2001:b07:6468:f312:5e2c:eb9a:a8b6:fd3e]) by smtp.gmail.com with ESMTPSA id n1sm2700678edf.45.2021.11.11.23.55.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 11 Nov 2021 23:55:36 -0800 (PST) Message-ID: <016d5b91-6910-2aca-0db1-a65079449454@redhat.com> Date: Fri, 12 Nov 2021 08:55:31 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: [PATCH v4 01/17] perf: Protect perf_guest_cbs with RCU Content-Language: en-US To: Peter Zijlstra Cc: Sean Christopherson , Ingo Molnar , Arnaldo Carvalho de Melo , Will Deacon , Mark Rutland , Russell King , Marc Zyngier , Catalin Marinas , Guo Ren , Nick Hu , Greentime Hu , Vincent Chen , Paul Walmsley , Palmer Dabbelt , Albert Ou , Thomas Gleixner , Borislav Petkov , Dave Hansen , x86@kernel.org, Boris Ostrovsky , Juergen Gross , Alexander Shishkin , Jiri Olsa , Namhyung Kim , James Morse , Alexandru Elisei , Suzuki K Poulose , "H. Peter Anvin" , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Stefano Stabellini , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-csky@vger.kernel.org, linux-riscv@lists.infradead.org, kvm@vger.kernel.org, xen-devel@lists.xenproject.org, Artem Kashkanov , Like Xu , Like Xu , Zhu Lingshan References: <20211111020738.2512932-1-seanjc@google.com> <20211111020738.2512932-2-seanjc@google.com> From: Paolo Bonzini In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/11/21 11:47, Peter Zijlstra wrote: >> This technically could be RCU_INIT_POINTER but it's not worth a respin. >> There are dozens of other occurrences, and if somebody wanted they >> could use Coccinelle to fix all of them. > I've been pushing the other way, trying to get rid of RCU_INIT_POINTER() > since rcu_assign_pointer(, NULL) actualy DTRT per __builtin_constant_p() > etc. Oh, that's pretty cool to know, thanks! Paolo > There's a very few sites where we use RCU_INIT_POINTER() with a !NULL > argument, and those are 'special'. >