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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-482c9c0acaesm4597451f8f.29.2026.08.23.02.51.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 23 Aug 2026 02:51:12 -0700 (PDT) Date: Sun, 23 Aug 2026 10:51:10 +0100 From: David Laight To: Sergey Shtylyov Cc: Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , , Subject: Re: [PATCH] r8152: simplify loops in generic_ocp_{read,write}() Message-ID: <20260823105110.231a88bc@pumpkin> In-Reply-To: <4a7604ab-c6ef-4552-b63b-3e7146ff42d0@auroraos.dev> References: <20260822202155.18632-1-s.shtylyov@auroraos.dev> <20260823091131.0254d6ab@pumpkin> <4a7604ab-c6ef-4552-b63b-3e7146ff42d0@auroraos.dev> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: netdev@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 Sun, 23 Aug 2026 11:20:30 +0300 Sergey Shtylyov wrote: > On 8/23/26 11:11 AM, David Laight wrote: > [...] > > >>> In generic_ocp_{read,write}(), the *while* loops look very strange: > >>> the last iteration is executed differently to the prior ones, doing > >>> some useless assignments before *break*. Move the code for the last > >>> iteration out of the loop bodies, dropping the pointless statements > >>> as well... > >>> > >>> Found by Linux Verification Center (linuxtesting.org) with the Svace > >>> static analysis tool. > >>> > >>> Signed-off-by: Sergey Shtylyov > >> > >> Actually, scratch this patch -- it's not entirely correct... :-/ > >> > >> [...] > >> > >>> diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c>>> index f61686433031..de9738bdce85 100644 > >>> --- a/drivers/net/usb/r8152.c > >>> +++ b/drivers/net/usb/r8152.c > >>> @@ -1431,27 +1431,19 @@ static int generic_ocp_read(struct r8152 *tp, u16 index, u16 size, > >>> if ((u32)index + (u32)size > 0xffff) > >>> return -EPERM; > >>> > >>> - while (size) { > >>> - if (size > limit) { > >>> - ret = get_registers(tp, index, type, limit, data); > >>> - if (ret < 0) > >>> - break; > >>> - > >>> - index += limit; > >>> - data += limit; > >>> - size -= limit; > >>> - } else { > >>> - ret = get_registers(tp, index, type, size, data); > >>> - if (ret < 0) > >>> - break; > >>> + while (size > limit) { > >>> + ret = get_registers(tp, index, type, limit, data); > >>> + if (ret < 0) > >>> + goto error1; > >>> > >>> - index += size; > >>> - data += size; > >>> - size = 0; > >>> - break; > >>> - } > >>> + index += limit; > >>> + data += limit; > >>> + size -= limit; > >>> } > >>> > >> > >> I forgot to check size for 0 here... > > > > I don't think it can be zero - assuming it isn't zero on entry. > > Even if so, anyways it can -- if size % limit == 0 on entry... Not with the 'size > limit' check at the top of the loop. David > > > David > [...] > > MBR, Sergey > >