Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751278AbaDZCjk (ORCPT ); Fri, 25 Apr 2014 22:39:40 -0400 Received: from mail-ig0-f172.google.com ([209.85.213.172]:47031 "EHLO mail-ig0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751177AbaDZCjj (ORCPT ); Fri, 25 Apr 2014 22:39:39 -0400 MIME-Version: 1.0 In-Reply-To: <535A7402.1060305@compro.net> References: <20140425070459.GA9155@devel> <20140425092607.GH26890@mwanda> <875455568.760649.1398423734122.JavaMail.root@mx2.compro.net> <535A5535.6000701@compro.net> <1016949935.761818.1398430870736.JavaMail.root@mx2.compro.net> <535A7402.1060305@compro.net> Date: Sat, 26 Apr 2014 11:39:38 +0900 Message-ID: Subject: Re: [PATCH] staging: dgap: implement error handling in dgap_tty_register() From: DaeSeok Youn To: Mark Hounschell Cc: Dan Carpenter , Lidza Louina , Greg KH , devel , driverdev-devel@linuxdriverproject.org, linux-kernel Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, please check below my comments. 2014-04-25 23:41 GMT+09:00 Mark Hounschell : > On 04/25/2014 08:59 AM, Dan Carpenter wrote: >> On Fri, Apr 25, 2014 at 08:29:41AM -0400, Mark Hounschell wrote: >>> On 04/25/2014 07:02 AM, DaeSeok Youn wrote: >>>> Hi, Dan. >>>> >>>> 2014-04-25 18:26 GMT+09:00 Dan Carpenter : >>>>> Mark, maybe you should add yourself to the MAINTAINERS entry for this >>>>> driver? >>>>> >>> >>> I'll look into this. I am clueless on what that would actually mean. >>> >> >> Just add your name with Lidza in the MAINTAINERS file so that people >> will CC you on all the patches. >> >> DIGI EPCA PCI PRODUCTS >> M: Lidza Louina >> L: driverdev-devel@linuxdriverproject.org >> S: Maintained >> F: drivers/staging/dgap/ >> >> You don't have to do it if you don't want to, but you seem to be working >> on this driver and I'm going to refer questions to you either way. :P >> >>>>> On Fri, Apr 25, 2014 at 04:04:59PM +0900, Daeseok Youn wrote: >>>>>> @@ -1263,7 +1277,8 @@ static int dgap_tty_register(struct board_t *brd) >>>>>> /* Register tty devices */ >>>>>> rc = tty_register_driver(brd->SerialDriver); >>>>>> if (rc < 0) >>>>>> - return rc; >>>>>> + goto free_print_ttys; >>>>>> + >>>>>> brd->dgap_Major_Serial_Registered = TRUE; >>>>>> dgap_BoardsByMajor[brd->SerialDriver->major] = brd; >>>>>> brd->dgap_Serial_Major = brd->SerialDriver->major; >>>>>> @@ -1273,13 +1288,29 @@ static int dgap_tty_register(struct board_t *brd) >>>>>> /* Register Transparent Print devices */ >>>>>> rc = tty_register_driver(brd->PrintDriver); >>>>>> if (rc < 0) >>>>>> - return rc; >>>>>> + goto unregister_serial_drv; >>>>>> + >>>>>> brd->dgap_Major_TransparentPrint_Registered = TRUE; >>>>>> dgap_BoardsByMajor[brd->PrintDriver->major] = brd; >>>>>> brd->dgap_TransparentPrint_Major = brd->PrintDriver->major; >>>>>> } >>>>>> >>>>>> return rc; >>>>>> + >>>>>> +unregister_serial_drv: >>>>>> + tty_unregister_driver(brd->SerialDriver); >>>>> >>>>> We only register the ->SerialDriver if someone else hasn't registered it >>>>> first? So this should be: >>>>> >>>>> if (we_were_the_ones_who_registered_the_serial_driver) >>>>> tty_unregister_driver(brd->SerialDriver); >>>>> >>>>> I haven't followed looked at this. Who else is registering the serial >>>>> driver? You have looked at this, what do you think? Or Mark. >>>> >>> >>> registering the brd->XxxxxDriver is only done when a board is detected >>> and only during the firmware_load process. If we fail to >>> tty_register_driver do we _need_ to tty_unregister_driver? Isn't that >>> like freeing after an alloc failure? >> >> The allocation is conditional so the free should be conditional. If we >> didn't allocate it, then we shouldn't free it. >> >> It wouldn't have even been a question except I'm not sure the allocation >> is *really* conditional because brd->dgap_Major_Serial_Registered might >> always be "false" like you guys seem to be saying. >> >>> >>>> I think brd struct is from dgap_Board array as global static variable >>>> when this function is >>>> called. So brd->dgap_Major_Serial_Registered is always "false". >>>> If dgap_NumBoards is less than MAXBOARDS, brd->SerialDriver should be >>>> registered. >>>> >>>> I'm not sure.. >>>> >>> >>> I don't see any check for (dgap_NumBoards < MAXBOARDS), which I think I >>> probably should, but I do see we are calling dgap_tty_register, which >>> can fail, without actually checking the return value. Also, yes, >>> dgap_Major_Xxxx_Registered seems to be always "false" until registered, >>> and it looks like dgap_Major_Xxxxx_Registered flags could be removed >>> because the only places we can unregister is at module_cleanup or >>> "after" it is already registered. >>> >>> What is the driver _supposed_ to do if we fail something on the second >>> or later board? Is the driver supposed to cleanup and exit or are we >>> supposed to stay loaded for the board/boards that are usable? >> >> Stay loaded. >> > > Then these tests on brd->dgap_Major_Serial_Registered need to stay in > there. If I have 3 boards and the second fails in some way, if I rmmod > the driver they will protect from unregistering a never registered one. > At least in the unregister code path. There is probably no need for them > in the register code path. I'll work up a patch for this. Should I update my patch? I think "if (!brd->dgap_Major_XXX_Registered)" line can be removed in this function, because if tty_register_driver() is failed just set "false" to "dgap_Major_XXX_Registered". dgap_Major_XXX_Registered only is used in cleaup function, right? So code like below rc = tty_register_driver(brd->PrintDriver); if (rc < 0) goto unregister_serial_drv; brd->dgap_Major_TransparentPrint_Registered = TRUE; ... unregister_serial_drv; brd->dgap_Major_Serial_Registered = false; tty_unregister_driver(brd->SerialDriver); Thanks. Regards, Daeseok Youn. > > I need to look at the (dgap_NumBoards < MAXBOARDS) thing too. > > Mark > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/