Re: [RFC] Remove or convert empty ioctls ?
From: Jeff Garzik
Date: Thu Oct 15 2009 - 08:14:14 EST
On 10/15/2009 05:20 AM, Thomas Gleixner wrote:
Hi,
while looking into pushing down BKL to ioctls I noticed that we have a
lot of ioctls which simply return -EINVAL or some other fancy error
code.
The question is whether we should convert them to unlocked_ioctl or
simply remove them and let the sys_ioctl code return the default
-ENOTTY error code.
One could argue that this is a user visible change, but OTOH there is
no particular value of EINVAL or any other weird error code when it
just says: there is no ioctl for this fd.
It seems like a mistake to generalize a rule out of this, especially if
it leads to error return values changing unexpectedly in years-old code.
"no particular value" is highly subjective, and I think unprovable,
without an exhaustive survey of userland programs interacting with
kernel drivers. Userland programs often interact with a -class- of
drivers, expecting predictable behavior from a DoThisThing ioctl, with
EINVAL or "other weird error code" returned intentionally.
Changing the return codes seems quite unwise.
Jeff
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