Re: [PATCH] staging: dgap: implement error handling in dgap_tty_register()

DaeSeok Youn
2014-05-16T09:40:32Z

Hi,

This patch haven't been updated over the past 3 weeks.
Will you check for me?

Regards,
Daeseok Youn.

2014-04-28 8:21 GMT+09:00 DaeSeok Youn <daeseok.youn@gmail.com>:
> OK. I'll make my patch based on Mark's patch.
> Thanks.
>
> Daeseok Youn.
>
> 2014-04-27 3:48 GMT+09:00 Dan Carpenter <dan.carpenter@oracle.com>:
>> On Sat, Apr 26, 2014 at 11:39:38AM +0900, DaeSeok Youn wrote:
>>> Hi,
>>>
>>> please check below my comments.
>>>
>>> 2014-04-25 23:41 GMT+09:00 Mark Hounschell <markh@compro.net>:
>>> > 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 <dan.carpenter@oracle.com>:
>>> >>>>> 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 <lidza.louina@gmail.com>
>>> >> 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".
>>
>> Mark sent a patch to remove the check. Could you redo your patch based
>> on his?
>>
>> regards,
>> dan carpenter
>>