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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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam01 X-Stat-Signature: hm6e1c553aeaia1qjsubpuh8icp6ea8y X-Rspam-User: X-Rspamd-Queue-Id: 0CE162001A X-HE-Tag: 1715338997-502236 X-HE-Meta: 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 eYjZq0ja m0nzNxiXrdGCXT3ckHom+Xr/XbHL/LvK1qrtC0db2YzHk4OPBmwQ4U8evH1iqRdKarxV+5DUXluNcLTx3WASVw/Q3WGsaQmI1VzZO5hFLpHKEFO8IVh985RTzQBk+c0CxtjJRNzO54dpwaazx47E5PpWG8fdDURzFsIXjSEQJAxlVIQWsXDZCGcSLmUbIduiR8FyBBaeU82TxtrK7K+AyHVuyB5minCg15v+rsJZQ1poqMHMrLtG2JCdXtmjIns8JTsZGpzrjZBflIVxen+lp8SpLhumXj49ZQH4l/FCN1C42hS+4FjRExLgyt0H7xR8bcXGgtwe0BZny4hJBsMPU7FQy0rQHJ0n5bhQs8yS7dAwRyts= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000100, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: [...] > > > + > > > + 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 >