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[193.116.127.232]) by smtp.gmail.com with ESMTPSA id j192-20020a638bc9000000b003c14af505fcsm10107925pge.20.2022.05.10.03.38.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 May 2022 03:38:28 -0700 (PDT) Date: Tue, 10 May 2022 20:38:22 +1000 From: Nicholas Piggin Subject: Re: [PATCH v6 20/29] init/main: Delay initialization of the lockup detector after smp_init() To: Ricardo Neri , Thomas Gleixner , x86@kernel.org References: <20220506000008.30892-1-ricardo.neri-calderon@linux.intel.com> <20220506000008.30892-21-ricardo.neri-calderon@linux.intel.com> In-Reply-To: <20220506000008.30892-21-ricardo.neri-calderon@linux.intel.com> MIME-Version: 1.0 Message-Id: <1652178524.7j2o02lrl8.astroid@bobo.none> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Ravi V. Shankar" , Andi Kleen , linuxppc-dev@lists.ozlabs.org, Joerg Roedel , linux-kernel@vger.kernel.org, Stephane Eranian , Ricardo Neri , iommu@lists.linux-foundation.org, Tony Luck , Suravee Suthikulpanit , Andrew Morton , David Woodhouse , Lu Baolu Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Excerpts from Ricardo Neri's message of May 6, 2022 9:59 am: > Certain implementations of the hardlockup detector require support for > Inter-Processor Interrupt shorthands. On x86, support for these can only > be determined after all the possible CPUs have booted once (in > smp_init()). Other architectures may not need such check. >=20 > lockup_detector_init() only performs the initializations of data > structures of the lockup detector. Hence, there are no dependencies on > smp_init(). I think this is the only real thing which affects other watchdog types? Not sure if it's a big problem, the secondary CPUs coming up won't have their watchdog active until quite late, and the primary could implement its own timeout in __cpu_up for secondary coming up, and IPI it to get traces if necessary which is probably more robust. Acked-by: Nicholas Piggin >=20 > Cc: Andi Kleen > Cc: Nicholas Piggin > Cc: Andrew Morton > Cc: Stephane Eranian > Cc: "Ravi V. Shankar" > Cc: iommu@lists.linux-foundation.org > Cc: linuxppc-dev@lists.ozlabs.org > Cc: x86@kernel.org > Reviewed-by: Tony Luck > Signed-off-by: Ricardo Neri > --- > Changes since v5: > * Introduced this patch >=20 > Changes since v4: > * N/A >=20 > Changes since v3: > * N/A >=20 > Changes since v2: > * N/A >=20 > Changes since v1: > * N/A > --- > init/main.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) >=20 > diff --git a/init/main.c b/init/main.c > index 98182c3c2c4b..62c52c9e4c2b 100644 > --- a/init/main.c > +++ b/init/main.c > @@ -1600,9 +1600,11 @@ static noinline void __init kernel_init_freeable(v= oid) > =20 > rcu_init_tasks_generic(); > do_pre_smp_initcalls(); > - lockup_detector_init(); > =20 > smp_init(); > + > + lockup_detector_init(); > + > sched_init_smp(); > =20 > padata_init(); > --=20 > 2.17.1 >=20 >=20