Re: [LTP] [PATCH] ioctl01: change the errno to ENOTTY when passed an invalid command

[Wanlong Gao <gaowanlong@cn.fujitsu.com>]

On 11/01/2012 04:05 PM, Jan Stancek wrote:
> 
> 
> ----- Original Message -----
>> From: "Wanlong Gao" <gaowanlong@cn.fujitsu.com>
>> To: "LTP" <ltp-list@lists.sourceforge.net>
>> Cc: "sanil kumar" <sanil.kumar@huawei.com>, "Mike Frysinger" <vapier@gentoo.org>, "shyju pv" <shyju.pv@huawei.com>,
>> "max maxiansheng" <max.maxiansheng@huawei.com>
>> Sent: Thursday, 1 November, 2012 5:00:19 AM
>> Subject: [LTP] [PATCH] ioctl01: change the errno to ENOTTY when passed an	invalid command
>>
>> As linus said at the below commit,
>> commit 07d106d0a33d6063d2061305903deb02489eba20
>> Author: Linus Torvalds <torvalds@linux-foundation.org>
>> Date:   Thu Jan 5 15:40:12 2012 -0800
>>
>>     vfs: fix up ENOIOCTLCMD error handling
>>
>>     We're doing some odd things there, which already messes up
>>     various users
>>     (see the net/socket.c code that this removes), and it was going
>>     to add
>>     yet more crud to the block layer because of the incorrect error
>>     code
>>     translation.
>>
>>     ENOIOCTLCMD is not an error return that should be returned to
>>     user mode
>>     from the "ioctl()" system call, but it should *not* be translated
>>     as
>>     EINVAL ("Invalid argument").  It should be translated as ENOTTY
>>     ("Inappropriate ioctl for device").
>>
>>     That EINVAL confusion has apparently so permeated some code that
>>     the
>>     block layer actually checks for it, which is sad.  We continue to
>>     do so
>>     for now, but add a big comment about how wrong that is, and we
>>     should
>>     remove it entirely eventually.  In the meantime, this tries to
>>     keep the
>>     changes localized to just the EINVAL -> ENOTTY fix, and removing
>>     code
>>     that makes it harder to do the right thing.
>>
>>     Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
>>
>> Return ENOTTY is right. And with the tty driver change with below
>> commit,
>> commit bbb63c514a3464342967237a51a21ea8f61ab951
>> Author: Wanlong Gao <gaowanlong@cn.fujitsu.com>
>> Date:   Mon Aug 27 15:23:12 2012 +0800
>>
>>     drivers:tty:fix up ENOIOCTLCMD error handling
>>
>>     At commit 07d106d0, Linus pointed out that ENOIOCTLCMD should be
>>     translated as ENOTTY to user mode.
>>     For example:
>>         fd = open("/dev/tty", O_RDWR);
>>         ioctl(fd, -1, &argp);
>>
>>     then the errno should be ENOTTY but not EINVAL.
>>
>>     Signed-off-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
>>     Acked-by: Alan Cox <alan@linux.intel.com>
>>     Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>>
>> The tty driver will return the right ENOTTY in upstream kernel when
>> passed a invalid ioctl command, so we fixed the LTP test case to
>> suit this return value change.
>> ---
>>  testcases/kernel/syscalls/ioctl/ioctl01.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/testcases/kernel/syscalls/ioctl/ioctl01.c
>> b/testcases/kernel/syscalls/ioctl/ioctl01.c
>> index 8b044e7..ef64896 100644
>> --- a/testcases/kernel/syscalls/ioctl/ioctl01.c
>> +++ b/testcases/kernel/syscalls/ioctl/ioctl01.c
>> @@ -87,7 +87,7 @@ struct test_case_t {
>>  	&fd, TCGETA, (struct termio *)-1, EFAULT},
>>  	    /* command is invalid */
>>  	{
>> -	&fd, INVAL_IOCTL, &termio, EINVAL},
>> +	&fd, INVAL_IOCTL, &termio, ENOTTY},
> 
> Won't this break on older kernels? Can we test for kernel version with tst_kvercmp()?

Surely will, this is also a trouble on my side. 
Does we treat this as a kernel bug or a kernel change?
I think if we treat it as a kernel bug, we needn't check the kernel version, while if
it just a kernel change, we need.
And, What's your opinion about this?

Thanks,
Wanlong Gao

> 
> Regards,
> Jan
> 
>>  	    /* file descriptor is for a regular file */
>>  	{
>>  	&fd1, TCGETA, &termio, ENOTTY},
>> --
>> 1.8.0
>>
>>
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> 


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