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[2003:cb:c70a:2700:1d28:26c3:b272:fcc6]) by smtp.gmail.com with ESMTPSA id l39-20020a05600c1d2700b0039c95b31e66sm2130939wms.31.2022.06.15.02.53.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 15 Jun 2022 02:53:33 -0700 (PDT) Message-ID: <1ef10873-c20f-afd8-e560-3b7fb5516f2b@redhat.com> Date: Wed, 15 Jun 2022 11:53:32 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.0 Subject: Re: [PATCH v8 3/7] crash: add generic infrastructure for crash hotplug support Content-Language: en-US To: Eric DeVolder , linux-kernel@vger.kernel.org, x86@kernel.org, kexec@lists.infradead.org, ebiederm@xmission.com, dyoung@redhat.com, bhe@redhat.com, vgoyal@redhat.com Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, nramas@linux.microsoft.com, thomas.lendacky@amd.com, robh@kernel.org, efault@gmx.de, rppt@kernel.org, konrad.wilk@oracle.com, boris.ostrovsky@oracle.com References: <20220505184603.1548-1-eric.devolder@oracle.com> <20220505184603.1548-4-eric.devolder@oracle.com> <62089f7b-4a3e-7dc8-1cda-84583e19d6fd@redhat.com> <24513679-d92d-ead1-2c1d-98db6a9bbdac@oracle.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <24513679-d92d-ead1-2c1d-98db6a9bbdac@oracle.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01.06.22 00:25, Eric DeVolder wrote: > > > On 5/31/22 08:15, David Hildenbrand wrote: >> On 12.05.22 18:10, Eric DeVolder wrote: >>> David, >>> Great questions! See inline responses below. >>> eric >> >> Sorry for the late reply, travel and vacation ... > No problem, greatly appreciate the feedback! > eric > >> >>>> >>>>> + >>>>> +#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_MEMORY_HOTPLUG) >>>>> +void __weak arch_crash_handle_hotplug_event(struct kimage *image, >>>>> + unsigned int hp_action, unsigned int cpu) >>>>> +{ >>>>> + WARN(1, "crash hotplug handler not implemented"); >>>> >>>> >>>> Won't that trigger on any arch that has CONFIG_HOTPLUG_CPU and CONFIG_MEMORY_HOTPLUG? >>>> I mean, you only implement it for x86 later in this series. Or what else stops this WARN from >>>> triggering? >>>> >>> You're correct. What about: printk_once(KERN_DEBUG "...") ? >> >> Why even bother about printing anything? If the feature is not >> supported, there should be some way for user space to figure out that it >> sill has to reload on hot(un)plug manually, no? > > I've changed this to WARN_ONCE(). If that isn't agreeable, I'll remove it. Please don't use WARN* on expected error paths. -- Thanks, David / dhildenb