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Wed, 18 Jun 2025 08:51:44 -0700 (PDT) Date: Wed, 18 Jun 2025 18:51:42 +0300 From: Dan Carpenter To: "Luck, Tony" Cc: Zaid Alali , rafael@kernel.org, lenb@kernel.org, james.morse@arm.com, bp@alien8.de, kees@kernel.org, gustavoars@kernel.org, Jonathan.Cameron@huawei.com, sudeep.holla@arm.com, jonathanh@nvidia.com, u.kleine-koenig@baylibre.com, viro@zeniv.linux.org.uk, ira.weiny@intel.com, alison.schofield@intel.com, dan.j.williams@intel.com, gregkh@linuxfoundation.org, peterz@infradead.org, dave.jiang@intel.com, Benjamin.Cheatham@amd.com, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH v9 5/7] ACPI: APEI: EINJ: Create debugfs files to enter device id and syndrome Message-ID: <2859fb82-1579-4d45-a8ee-2e3de184fa0d@suswa.mountain> References: <20250612231327.84360-1-zaidal@os.amperecomputing.com> <20250612231327.84360-6-zaidal@os.amperecomputing.com> <3a143d53-8731-4afc-9117-bac49ea96db1@suswa.mountain> 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: On Wed, Jun 18, 2025 at 08:30:10AM -0700, Luck, Tony wrote: > On Wed, Jun 18, 2025 at 06:21:39PM +0300, Dan Carpenter wrote: > > On Thu, Jun 12, 2025 at 04:13:25PM -0700, Zaid Alali wrote: > > > +static ssize_t u128_read(struct file *f, char __user *buf, size_t count, loff_t *off) > > > +{ > > > + char output[2 * COMPONENT_LEN + 1]; > > > + u8 *data = f->f_inode->i_private; > > > + int i; > > > + > > > + if (*off >= sizeof(output)) > > > + return 0; > > > > No need for this check. simple_read_from_buffer() will do the > > right thing. > > True. But why waste cycles populating the output buffer > when it will be ignored? The normal flow here is that > a user will likely try to read a sized buffer > and get back 33 bytes. Then read again to find EOF. That > second read doesn't need to do all the "sprintf()"s. > Ah. Okay, I didn't realize that. regards, dan carpenter