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[34.78.140.88]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-41fccbe8fc6sm59614295e9.4.2024.05.10.04.03.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 10 May 2024 04:03:16 -0700 (PDT) Date: Fri, 10 May 2024 12:03:12 +0100 From: Vincent Donnefort To: David Hildenbrand Cc: Steven Rostedt , mhiramat@kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, mathieu.desnoyers@efficios.com, kernel-team@android.com, rdunlap@infradead.org, rppt@kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v22 2/5] ring-buffer: Introducing ring-buffer mapping functions Message-ID: References: <20240430111354.637356-1-vdonnefort@google.com> <20240430111354.637356-3-vdonnefort@google.com> <20240507223402.206d6ddc@rorschach.local.home> Precedence: bulk X-Mailing-List: linux-trace-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: [...] > > > + > > > + while (s < nr_subbufs && p < nr_pages) { > > > + struct page *page = virt_to_page(cpu_buffer->subbuf_ids[s]); > > > + int off = 0; > > > + > > > + for (; off < (1 << (subbuf_order)); off++, page++) { > > > + if (p >= nr_pages) > > > + break; > > > + > > > + pages[p++] = page; > > > + } > > > + s++; > > > + } > > > > The above can be made to: > > > > while (p < nr_pages) { > > struct page *page; > > int off = 0; > > > > if (WARN_ON_ONCE(s >= nr_subbufs)) > > break; > > I'm not particularly happy about us calling vm_insert_pages with NULL > pointers stored in pages. > > Should we instead do > > if (WARN_ON_ONCE(s >= nr_subbufs)) { > err = -EINVAL; > goto out; > } > > ? I could also nr_pages = p in the event of s >= nr_subbufs... but that really that shouldn't happen so let's return an error. > > -- > Cheers, > > David / dhildenb >