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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-45eaa93630asm1418858f8f.25.2026.05.21.03.04.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 May 2026 03:04:03 -0700 (PDT) Date: Thu, 21 May 2026 11:04:02 +0100 From: David Laight To: Greg Kroah-Hartman Cc: Tejun Heo , driver-core@lists.linux.dev, linux-kernel@vger.kernel.org, "Rafael J. Wysocki" , Danilo Krummrich , NeilBrown Subject: Re: [PATCH] sysfs: clamp show() return value in sysfs_kf_read() Message-ID: <20260521110402.7bc76f4e@pumpkin> In-Reply-To: <2026052129-mustard-sepia-5cd6@gregkh> References: <2026052000-drove-unicycle-d61b@gregkh> <3fb84b4c71fce994cfe1e06a5fe3970f@kernel.org> <2026052129-mustard-sepia-5cd6@gregkh> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) 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-Transfer-Encoding: 7bit On Thu, 21 May 2026 08:18:32 +0200 Greg Kroah-Hartman wrote: > On Wed, May 20, 2026 at 08:19:34AM -1000, Tejun Heo wrote: > > Hello, > > > > Two nits: > > > > - Buffer is atomic_write_len ?: PAGE_SIZE, so probably better to clamp > > to that than hardcode PAGE_SIZE. > > Where is that check at? And sysfs_kf_seq_show() doesn't check it this > way, should that change? It would be better to always fix the 'show' buffer at PAGE_SIZE (or 4k). The only place that uses is different value is the cgroup code and I think it needs to support longer writes (100 + 6 * NR_CPUS). I've not looked at how it handles the matching reads - I presume they exist. If the data is binary, or it uses seq_printf() then it can just support a longer dynamically allocated buffer. -- David > > > - pr_warn() instead of bare printk()? > > This is copying the message in sysfs_kf_seq_show() that has the same > exact format. I will send a follow-on patch to make both the same. > > thanks, > > greg k-h >