From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EB944C43219 for ; Thu, 2 May 2019 14:57:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A7DE020652 for ; Thu, 2 May 2019 14:57:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726371AbfEBO50 (ORCPT ); Thu, 2 May 2019 10:57:26 -0400 Received: from gateway22.websitewelcome.com ([192.185.46.152]:28421 "EHLO gateway22.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726203AbfEBO50 (ORCPT ); Thu, 2 May 2019 10:57:26 -0400 Received: from cm10.websitewelcome.com (cm10.websitewelcome.com [100.42.49.4]) by gateway22.websitewelcome.com (Postfix) with ESMTP id BC231228D5 for ; Thu, 2 May 2019 09:57:24 -0500 (CDT) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id MD9IhNJvK2PzOMD9IhqvpZ; Thu, 02 May 2019 09:57:24 -0500 X-Authority-Reason: nr=8 Received: from [189.250.119.203] (port=57848 helo=[192.168.1.76]) by gator4166.hostgator.com with esmtpsa (TLSv1.2:ECDHE-RSA-AES128-GCM-SHA256:128) (Exim 4.91) (envelope-from ) id 1hMD9I-000sPl-8y; Thu, 02 May 2019 09:57:24 -0500 Subject: Re: [PATCH v2] USB: serial: io_edgeport: mark expected switch fall-throughs To: Greg Kroah-Hartman Cc: Johan Hovold , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, Kees Cook References: <20190501213329.GA26972@embeddedor> <20190502102608.GS26546@localhost> <20190502135636.GT26546@localhost> <20190502144041.GA17960@kroah.com> <20190502144729.GB17960@kroah.com> From: "Gustavo A. R. Silva" Openpgp: preference=signencrypt Autocrypt: addr=gustavo@embeddedor.com; keydata= mQINBFssHAwBEADIy3ZoPq3z5UpsUknd2v+IQud4TMJnJLTeXgTf4biSDSrXn73JQgsISBwG 2Pm4wnOyEgYUyJd5tRWcIbsURAgei918mck3tugT7AQiTUN3/5aAzqe/4ApDUC+uWNkpNnSV tjOx1hBpla0ifywy4bvFobwSh5/I3qohxDx+c1obd8Bp/B/iaOtnq0inli/8rlvKO9hp6Z4e DXL3PlD0QsLSc27AkwzLEc/D3ZaqBq7ItvT9Pyg0z3Q+2dtLF00f9+663HVC2EUgP25J3xDd 496SIeYDTkEgbJ7WYR0HYm9uirSET3lDqOVh1xPqoy+U9zTtuA9NQHVGk+hPcoazSqEtLGBk YE2mm2wzX5q2uoyptseSNceJ+HE9L+z1KlWW63HhddgtRGhbP8pj42bKaUSrrfDUsicfeJf6 m1iJRu0SXYVlMruGUB1PvZQ3O7TsVfAGCv85pFipdgk8KQnlRFkYhUjLft0u7CL1rDGZWDDr NaNj54q2CX9zuSxBn9XDXvGKyzKEZ4NY1Jfw+TAMPCp4buawuOsjONi2X0DfivFY+ZsjAIcx qQMglPtKk/wBs7q2lvJ+pHpgvLhLZyGqzAvKM1sVtRJ5j+ARKA0w4pYs5a5ufqcfT7dN6TBk LXZeD9xlVic93Ju08JSUx2ozlcfxq+BVNyA+dtv7elXUZ2DrYwARAQABtCxHdXN0YXZvIEEu IFIuIFNpbHZhIDxndXN0YXZvQGVtYmVkZGVkb3IuY29tPokCPQQTAQgAJwUCWywcDAIbIwUJ CWYBgAULCQgHAgYVCAkKCwIEFgIDAQIeAQIXgAAKCRBHBbTLRwbbMZ6tEACk0hmmZ2FWL1Xi l/bPqDGFhzzexrdkXSfTTZjBV3a+4hIOe+jl6Rci/CvRicNW4H9yJHKBrqwwWm9fvKqOBAg9 obq753jydVmLwlXO7xjcfyfcMWyx9QdYLERTeQfDAfRqxir3xMeOiZwgQ6dzX3JjOXs6jHBP cgry90aWbaMpQRRhaAKeAS14EEe9TSIly5JepaHoVdASuxklvOC0VB0OwNblVSR2S5i5hSsh ewbOJtwSlonsYEj4EW1noQNSxnN/vKuvUNegMe+LTtnbbocFQ7dGMsT3kbYNIyIsp42B5eCu JXnyKLih7rSGBtPgJ540CjoPBkw2mCfhj2p5fElRJn1tcX2McsjzLFY5jK9RYFDavez5w3lx JFgFkla6sQHcrxH62gTkb9sUtNfXKucAfjjCMJ0iuQIHRbMYCa9v2YEymc0k0RvYr43GkA3N PJYd/vf9vU7VtZXaY4a/dz1d9dwIpyQARFQpSyvt++R74S78eY/+lX8wEznQdmRQ27kq7BJS R20KI/8knhUNUJR3epJu2YFT/JwHbRYC4BoIqWl+uNvDf+lUlI/D1wP+lCBSGr2LTkQRoU8U 64iK28BmjJh2K3WHmInC1hbUucWT7Swz/+6+FCuHzap/cjuzRN04Z3Fdj084oeUNpP6+b9yW e5YnLxF8ctRAp7K4yVlvA7kCDQRbLBwMARAAsHCE31Ffrm6uig1BQplxMV8WnRBiZqbbsVJB H1AAh8tq2ULl7udfQo1bsPLGGQboJSVN9rckQQNahvHAIK8ZGfU4Qj8+CER+fYPp/MDZj+t0 DbnWSOrG7z9HIZo6PR9z4JZza3Hn/35jFggaqBtuydHwwBANZ7A6DVY+W0COEU4of7CAahQo 5NwYiwS0lGisLTqks5R0Vh+QpvDVfuaF6I8LUgQR/cSgLkR//V1uCEQYzhsoiJ3zc1HSRyOP otJTApqGBq80X0aCVj1LOiOF4rrdvQnj6iIlXQssdb+WhSYHeuJj1wD0ZlC7ds5zovXh+FfF l5qH5RFY/qVn3mNIVxeO987WSF0jh+T5ZlvUNdhedGndRmwFTxq2Li6GNMaolgnpO/CPcFpD jKxY/HBUSmaE9rNdAa1fCd4RsKLlhXda+IWpJZMHlmIKY8dlUybP+2qDzP2lY7kdFgPZRU+e zS/pzC/YTzAvCWM3tDgwoSl17vnZCr8wn2/1rKkcLvTDgiJLPCevqpTb6KFtZosQ02EGMuHQ I6Zk91jbx96nrdsSdBLGH3hbvLvjZm3C+fNlVb9uvWbdznObqcJxSH3SGOZ7kCHuVmXUcqoz ol6ioMHMb+InrHPP16aVDTBTPEGwgxXI38f7SUEn+NpbizWdLNz2hc907DvoPm6HEGCanpcA EQEAAYkCJQQYAQgADwUCWywcDAIbDAUJCWYBgAAKCRBHBbTLRwbbMdsZEACUjmsJx2CAY+QS UMebQRFjKavwXB/xE7fTt2ahuhHT8qQ/lWuRQedg4baInw9nhoPE+VenOzhGeGlsJ0Ys52sd XvUjUocKgUQq6ekOHbcw919nO5L9J2ejMf/VC/quN3r3xijgRtmuuwZjmmi8ct24TpGeoBK4 WrZGh/1hAYw4ieARvKvgjXRstcEqM5thUNkOOIheud/VpY+48QcccPKbngy//zNJWKbRbeVn imua0OpqRXhCrEVm/xomeOvl1WK1BVO7z8DjSdEBGzbV76sPDJb/fw+y+VWrkEiddD/9CSfg fBNOb1p1jVnT2mFgGneIWbU0zdDGhleI9UoQTr0e0b/7TU+Jo6TqwosP9nbk5hXw6uR5k5PF 8ieyHVq3qatJ9K1jPkBr8YWtI5uNwJJjTKIA1jHlj8McROroxMdI6qZ/wZ1ImuylpJuJwCDC ORYf5kW61fcrHEDlIvGc371OOvw6ejF8ksX5+L2zwh43l/pKkSVGFpxtMV6d6J3eqwTafL86 YJWH93PN+ZUh6i6Rd2U/i8jH5WvzR57UeWxE4P8bQc0hNGrUsHQH6bpHV2lbuhDdqo+cM9eh GZEO3+gCDFmKrjspZjkJbB5Gadzvts5fcWGOXEvuT8uQSvl+vEL0g6vczsyPBtqoBLa9SNrS VtSixD1uOgytAP7RWS474w== Message-ID: <122f54b9-16e9-317b-42af-88bef6d6e3b0@embeddedor.com> Date: Thu, 2 May 2019 09:57:22 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190502144729.GB17960@kroah.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - gator4166.hostgator.com X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - embeddedor.com X-BWhitelist: no X-Source-IP: 189.250.119.203 X-Source-L: No X-Exim-ID: 1hMD9I-000sPl-8y X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: ([192.168.1.76]) [189.250.119.203]:57848 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 9 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/2/19 9:47 AM, Greg Kroah-Hartman wrote: > On Thu, May 02, 2019 at 04:40:41PM +0200, Greg Kroah-Hartman wrote: >> On Thu, May 02, 2019 at 09:28:37AM -0500, Gustavo A. R. Silva wrote: >>> >>> >>> On 5/2/19 8:56 AM, Johan Hovold wrote: >>>> On Thu, May 02, 2019 at 08:22:30AM -0500, Gustavo A. R. Silva wrote: >>>>> >>>>> >>>>> On 5/2/19 5:26 AM, Johan Hovold wrote: >>>>>> On Wed, May 01, 2019 at 04:33:29PM -0500, Gustavo A. R. Silva wrote: >>>>>>> In preparation to enabling -Wimplicit-fallthrough, mark switch >>>>>>> cases where we are expecting to fall through. >>>>>>> >>>>>>> This patch fixes the following warnings: >>>>>>> >>>>>>> drivers/usb/serial/io_edgeport.c: In function ‘process_rcvd_data’: >>>>>>> drivers/usb/serial/io_edgeport.c:1750:7: warning: this statement may fall through [-Wimplicit-fallthrough=] >>>>>>> if (bufferLength == 0) { >>>>>>> ^ >>>>>>> drivers/usb/serial/io_edgeport.c:1755:3: note: here >>>>>>> case EXPECT_HDR2: >>>>>>> ^~~~ >>>>>>> drivers/usb/serial/io_edgeport.c:1810:8: warning: this statement may fall through [-Wimplicit-fallthrough=] >>>>>>> if (bufferLength == 0) { >>>>>>> ^ >>>>>>> drivers/usb/serial/io_edgeport.c:1816:3: note: here >>>>>>> case EXPECT_DATA: /* Expect data */ >>>>>>> ^~~~ >>>>>>> >>>>>>> Warning level 3 was used: -Wimplicit-fallthrough=3 >>>>>>> >>>>>>> Notice that, in this particular case, the code comments are modified >>>>>>> in accordance with what GCC is expecting to find. >>>>>>> >>>>>>> This patch is part of the ongoing efforts to enable >>>>>>> -Wimplicit-fallthrough. >>>>>>> >>>>>>> Signed-off-by: Gustavo A. R. Silva >>>>>>> --- >>>>>>> Changes in v2: >>>>>>> - Warning level 3 is now used: -Wimplicit-fallthrough=3 >>>>>>> instead of warning level 2. >>>>>>> - All warnings in the switch statement are addressed now. >>>>>>> >>>>>>> Notice that these are the last remaining fall-through warnings >>>>>>> in the USB subsystem. :) >>>>>> >>>>>>> drivers/usb/serial/io_edgeport.c | 3 ++- >>>>>>> 1 file changed, 2 insertions(+), 1 deletion(-) >>>>>>> >>>>>>> diff --git a/drivers/usb/serial/io_edgeport.c b/drivers/usb/serial/io_edgeport.c >>>>>>> index 4ca31c0e4174..7ad10328f4e2 100644 >>>>>>> --- a/drivers/usb/serial/io_edgeport.c >>>>>>> +++ b/drivers/usb/serial/io_edgeport.c >>>>>>> @@ -1751,7 +1751,7 @@ static void process_rcvd_data(struct edgeport_serial *edge_serial, >>>>>>> edge_serial->rxState = EXPECT_HDR2; >>>>>>> break; >>>>>>> } >>>>>>> - /* otherwise, drop on through */ >>>>>>> + /* Fall through - otherwise, drop on through */ >>>>>>> case EXPECT_HDR2: >>>>>>> edge_serial->rxHeader2 = *buffer; >>>>>>> ++buffer; >>>>>>> @@ -1813,6 +1813,7 @@ static void process_rcvd_data(struct edgeport_serial *edge_serial, >>>>>>> } >>>>>>> /* Else, drop through */ >>>>>>> } >>>>>>> + /* Fall through */ >>>>>>> case EXPECT_DATA: /* Expect data */ >>>>>> >>>>>> Looks like you forgot to take the original review feedback you got into >>>>>> account: >>>>>> >>>>>> https://lkml.kernel.org/r/87k1zf4k24.fsf@miraculix.mork.no >>>>>> >>>>> >>>>> Oh, the thing is that the fall-through comments have to be placed at >>>>> the very bottom of the case. Also, based on that feedback, this time >>>>> I left the "Else, drop through" comment in place, so people can be >>>>> informed that such fall-through is conditional. >>>>> >>>>> What do you think about this: >>>>> >>>>> diff --git a/drivers/usb/serial/io_edgeport.c b/drivers/usb/serial/io_edgeport.c >>>>> index 4ca31c0e4174..52f27fc82563 100644 >>>>> --- a/drivers/usb/serial/io_edgeport.c >>>>> +++ b/drivers/usb/serial/io_edgeport.c >>>>> @@ -1751,7 +1751,7 @@ static void process_rcvd_data(struct edgeport_serial *edge_serial, >>>>> edge_serial->rxState = EXPECT_HDR2; >>>>> break; >>>>> } >>>>> - /* otherwise, drop on through */ >>>>> + /* Fall through - otherwise, drop on through */ >>>>> case EXPECT_HDR2: >>>>> edge_serial->rxHeader2 = *buffer; >>>>> ++buffer; >>>>> @@ -1813,6 +1813,11 @@ static void process_rcvd_data(struct edgeport_serial *edge_serial, >>>>> } >>>>> /* Else, drop through */ >>>>> } >>>>> + /* Beware that, currently, there are at least three >>>>> + * break statements in this case block, so the >>>>> + * fall-through marked below is NOT unconditional. >>>>> + */ >>>>> + /* Fall through */ >>>>> case EXPECT_DATA: /* Expect data */ >>>>> if (bufferLength < edge_serial->rxBytesRemaining) { >>>>> rxLen = bufferLength; >>>> >>>> It's better than v2, but I thought you said you were gonna look into >>>> restructuring the code to maintain (or even improve) readability? >>>> >>> >>> At first, I thought about that, but now I don't think that's realistic. >>> I'd turn the if-else into a switch, and based on the history of feedback >>> on this patch, we will end up having the same complains about the break >>> statements in that new switch and the possibility of a fall-through to >>> case EXPECT_DATA. At the end I would still have to add a comment explaining >>> that the last fall-through mark in unconditional. >> >> I love it how no one is blaming the original author of this code (i.e. >> me...) >> >> Let me see if I can fix it up to be more "sane", this is my fault. > > How about the following patch? Johan, this look nicer to you? It makes > more sense to me. > Thanks, Greg. Just notice that, unfortunately, the original complains are still applicable to your patch. :/ Thanks -- Gustavo > And in looking at the history, I can't claim total credit for this > monstrosity, it was originally written by someone else, I just "cleaned > it up" back in 2001, to get it into mergable shape. Clearly "mergable > shape" was much looser back then :) > > thanks, > > greg k-h > > ---------------- > > diff --git a/drivers/usb/serial/io_edgeport.c b/drivers/usb/serial/io_edgeport.c > index 4ca31c0e4174..732081b3718f 100644 > --- a/drivers/usb/serial/io_edgeport.c > +++ b/drivers/usb/serial/io_edgeport.c > @@ -1751,7 +1751,8 @@ static void process_rcvd_data(struct edgeport_serial *edge_serial, > edge_serial->rxState = EXPECT_HDR2; > break; > } > - /* otherwise, drop on through */ > + /* Fall through */ > + > case EXPECT_HDR2: > edge_serial->rxHeader2 = *buffer; > ++buffer; > @@ -1790,29 +1791,21 @@ static void process_rcvd_data(struct edgeport_serial *edge_serial, > edge_serial->rxHeader2, 0); > edge_serial->rxState = EXPECT_HDR1; > break; > - } else { > - edge_serial->rxPort = > - IOSP_GET_HDR_PORT(edge_serial->rxHeader1); > - edge_serial->rxBytesRemaining = > - IOSP_GET_HDR_DATA_LEN( > - edge_serial->rxHeader1, > - edge_serial->rxHeader2); > - dev_dbg(dev, "%s - Data for Port %u Len %u\n", > - __func__, > - edge_serial->rxPort, > - edge_serial->rxBytesRemaining); > - > - /* ASSERT(DevExt->RxPort < DevExt->NumPorts); > - * ASSERT(DevExt->RxBytesRemaining < > - * IOSP_MAX_DATA_LENGTH); > - */ > - > - if (bufferLength == 0) { > - edge_serial->rxState = EXPECT_DATA; > - break; > - } > - /* Else, drop through */ > } > + > + edge_serial->rxPort = IOSP_GET_HDR_PORT(edge_serial->rxHeader1); > + edge_serial->rxBytesRemaining = IOSP_GET_HDR_DATA_LEN(edge_serial->rxHeader1, > + edge_serial->rxHeader2); > + dev_dbg(dev, "%s - Data for Port %u Len %u\n", __func__, > + edge_serial->rxPort, > + edge_serial->rxBytesRemaining); > + > + if (bufferLength == 0) { > + edge_serial->rxState = EXPECT_DATA; > + break; > + } > + /* Fall through */ > + > case EXPECT_DATA: /* Expect data */ > if (bufferLength < edge_serial->rxBytesRemaining) { > rxLen = bufferLength; >