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[37.158.143.169]) by smtp.gmail.com with ESMTPSA id 126sm1734578wmz.28.2021.11.09.00.21.30 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 09 Nov 2021 00:21:30 -0800 (PST) Subject: Re: [PATCH v3 2/2] accel/tcg: Register a force_rcu notifier From: Richard Henderson To: Greg Kurz , qemu-devel@nongnu.org References: <20211108113353.133462-1-groug@kaod.org> <20211108113353.133462-3-groug@kaod.org> <5892d9dd-5f0c-d745-6a0a-84485e0e29c3@linaro.org> Message-ID: <8a184041-39ad-1207-f32b-673e2b8da0f2@linaro.org> Date: Tue, 9 Nov 2021 09:21:27 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <5892d9dd-5f0c-d745-6a0a-84485e0e29c3@linaro.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Host-Lookup-Failed: Reverse DNS lookup failed for 2a00:1450:4864:20::334 (failed) Received-SPF: pass client-ip=2a00:1450:4864:20::334; envelope-from=richard.henderson@linaro.org; helo=mail-wm1-x334.google.com X-Spam_score_int: -46 X-Spam_score: -4.7 X-Spam_bar: ---- X-Spam_report: (-4.7 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-3.364, PDS_HP_HELO_NORDNS=0.001, RCVD_IN_DNSWL_NONE=-0.0001, RDNS_NONE=0.793, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Paolo Bonzini , Eduardo Habkost , qemu-stable@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 11/9/21 8:54 AM, Richard Henderson wrote: > On 11/8/21 12:33 PM, Greg Kurz wrote: >> +static void rr_force_rcu(Notifier *notify, void *data) >> +{ >> +    /* >> +     * Called with rcu_registry_lock held, using async_run_on_cpu() ensures >> +     * that there are no deadlocks. >> +     */ >> +    async_run_on_cpu(first_cpu, do_nothing, RUN_ON_CPU_NULL); >> +} > > Should first_cpu really be rr_current_cpu? > It's not clear to me that this will work for -smp 2 -cpu thread=single. Alternately, no async_run_on_cpu at all, just rr_kick_next_cpu(). r~