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[84.236.113.97]) by smtp.gmail.com with ESMTPSA id h9-20020a1709060f4900b00a472c4b9486sm2995392ejj.84.2024.03.30.04.12.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 30 Mar 2024 04:12:08 -0700 (PDT) Sender: Ingo Molnar Date: Sat, 30 Mar 2024 12:12:06 +0100 From: Ingo Molnar To: Reinette Chatre Cc: fenghua.yu@intel.com, bp@alien8.de, james.morse@arm.com, tony.luck@intel.com, peternewman@google.com, babu.moger@amd.com, tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, james.greenhalgh@arm.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86/resctrl: Fix uninitialized memory read when last CPU of domain goes offline Message-ID: References: <979cfd9522021aa6001f8995cd36fb56e1c9cd39.1711659804.git.reinette.chatre@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: * Reinette Chatre wrote: > Hi Ingo, > > On 3/29/2024 12:01 AM, Ingo Molnar wrote: > > > > * Reinette Chatre wrote: > > > >> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h > >> index c99f26ebe7a6..4f9ef35626a7 100644 > >> --- a/arch/x86/kernel/cpu/resctrl/internal.h > >> +++ b/arch/x86/kernel/cpu/resctrl/internal.h > >> @@ -85,6 +85,10 @@ cpumask_any_housekeeping(const struct cpumask *mask, int exclude_cpu) > >> if (cpu < nr_cpu_ids && !tick_nohz_full_cpu(cpu)) > >> return cpu; > >> > >> + /* Only continue if tick_nohz_full_mask has been initialized. */ > >> + if (!tick_nohz_full_enabled()) > >> + return cpu; > >> + > > > > So we already have this a few lines up: > > > > if (!IS_ENABLED(CONFIG_NO_HZ_FULL)) > > return cpu; > > > > And we can combine the two checks into a single one, with the patch > > below, right? > > Right. Indeed. Doing so is most appropriate. Thank you very much. > > > > > Untested. > > Tested-by: Reinette Chatre > Reviewed-by: Reinette Chatre Please just pick up my optimization to your fix and submit a v2 - you did all the hard work. Thanks, Ingo