Messages in this thread | | | Date | Thu, 15 Oct 2009 08:12:44 -0400 | From | Jeff Garzik <> | Subject | Re: [RFC] Remove or convert empty ioctls ? |
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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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