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Mon, 30 Sep 2024 09:28:20 -0700 (PDT) Received: from sunil-laptop ([106.51.192.229]) by smtp.gmail.com with ESMTPSA id 5614622812f47-3e3935c67e6sm2513939b6e.54.2024.09.30.09.28.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 Sep 2024 09:28:18 -0700 (PDT) Date: Mon, 30 Sep 2024 21:58:10 +0530 From: Sunil V L To: Miquel =?utf-8?B?U2FiYXTDqSBTb2zDoA==?= Cc: paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, cuiyunhui@bytedance.com, sudeep.holla@arm.com, jeremy.linton@arm.com, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] riscv: Prevent a bad reference count on CPU nodes Message-ID: References: <20240913080053.36636-1-mikisabate@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20240913080053.36636-1-mikisabate@gmail.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240930_092822_106085_2A0A22D3 X-CRM114-Status: GOOD ( 26.78 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; 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Mon, 30 Sep 2024 09:28:20 -0700 (PDT) Received: from sunil-laptop ([106.51.192.229]) by smtp.gmail.com with ESMTPSA id 5614622812f47-3e3935c67e6sm2513939b6e.54.2024.09.30.09.28.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 Sep 2024 09:28:18 -0700 (PDT) Date: Mon, 30 Sep 2024 21:58:10 +0530 From: Sunil V L To: Miquel =?utf-8?B?U2FiYXTDqSBTb2zDoA==?= Cc: paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, cuiyunhui@bytedance.com, sudeep.holla@arm.com, jeremy.linton@arm.com, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] riscv: Prevent a bad reference count on CPU nodes Message-ID: References: <20240913080053.36636-1-mikisabate@gmail.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=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20240913080053.36636-1-mikisabate@gmail.com> On Fri, Sep 13, 2024 at 10:00:52AM +0200, Miquel Sabaté Solà wrote: > When populating cache leaves we previously fetched the CPU device node > at the very beginning. But when ACPI is enabled we go through a > specific branch which returns early and does not call 'of_node_put' for > the node that was acquired. > > Since we are not using a CPU device node for the ACPI code anyways, we > can simply move the initialization of it just passed the ACPI block, and > we are guaranteed to have an 'of_node_put' call for the acquired node. > This prevents a bad reference count of the CPU device node. > > Moreover, the previous function did not check for errors when acquiring > the device node, so a return -ENOENT has been added for that case. > > Signed-off-by: Miquel Sabaté Solà > --- > I was wondering if this should also be sent to stable, but I have not seen > a report on it, and this is not responsible for an oops or anything like that. > So in the end I decided not to, but maybe you consider otherwise. > > arch/riscv/kernel/cacheinfo.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/arch/riscv/kernel/cacheinfo.c b/arch/riscv/kernel/cacheinfo.c > index d6c108c50cba..d32dfdba083e 100644 > --- a/arch/riscv/kernel/cacheinfo.c > +++ b/arch/riscv/kernel/cacheinfo.c > @@ -75,8 +75,7 @@ int populate_cache_leaves(unsigned int cpu) > { > struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu); > struct cacheinfo *this_leaf = this_cpu_ci->info_list; > - struct device_node *np = of_cpu_device_node_get(cpu); > - struct device_node *prev = NULL; > + struct device_node *np, *prev; > int levels = 1, level = 1; > > if (!acpi_disabled) { > @@ -100,6 +99,10 @@ int populate_cache_leaves(unsigned int cpu) > return 0; > } > > + np = of_cpu_device_node_get(cpu); > + if (!np) > + return -ENOENT; > + LGTM. Reviewed-by: Sunil V L Thanks, Sunil