Commit: 63ab4325d0df2ccefaeb932210d4046f2223e338 - linux_3.x_apsh4a0a (git)

linux-3.0.x for AP-SH4A-0A Board

Commit MetaInfo

• Révision: 63ab4325d0df2ccefaeb932210d4046f2223e338 (tree)
• l'heure: 2011-08-05 13:58:34
• Auteur: Stefan Richter <stefanr@s5r6...>
• Commiter: Greg Kroah-Hartman

Message de Log

firewire: cdev: return -ENOTTY for unimplemented ioctls, not -EINVAL

commit d873d794235efa590ab3c94d5ee22bb1fab19ac4 upstream.

On Jun 27 Linus Torvalds wrote:

The correct error code for "I don't understand this ioctl" is ENOTTY.
The naming may be odd, but you should think of that error value as a
"unrecognized ioctl number, you're feeding me random numbers that I
don't understand and I assume for historical reasons that you tried to
do some tty operation on me".

[...]

The EINVAL thing goes way back, and is a disaster. It predates Linux
itself, as far as I can tell. You'll find lots of man-pages that have
this line in it:

>

EINVAL Request or argp is not valid.

>

and it shows up in POSIX etc. And sadly, it generally shows up
_before_ the line that says

>

ENOTTY The specified request does not apply to the kind of object
that the descriptor d references.

>

so a lot of people get to the EINVAL, and never even notice the ENOTTY.

[...]

At least glibc (and hopefully other C libraries) use a _string_ that
makes much more sense: strerror(ENOTTY) is "Inappropriate ioctl for
device"

So let's correct this in the <linux/firewire-cdev.h> ABI while it is
still young, relative to distributor adoption.

Side note: We return -ENOTTY not only on _IOC_TYPE or _IOC_NR mismatch,
but also on _IOC_SIZE mismatch. An ioctl with an unsupported size of
argument structure can be seen as an unsupported version of that ioctl.

Signed-off-by: Stefan Richter <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

Change Summary

• modified: drivers/firewire/core-cdev.c

Modification

--- a/drivers/firewire/core-cdev.c
+++ b/drivers/firewire/core-cdev.c
@@ -1583,7 +1583,7 @@ static int dispatch_ioctl(struct client *client,
 	if (_IOC_TYPE(cmd) != '#' ||
 	    _IOC_NR(cmd) >= ARRAY_SIZE(ioctl_handlers) ||
 	    _IOC_SIZE(cmd) > sizeof(buffer))
-		return -EINVAL;
+		return -ENOTTY;
 
 	if (_IOC_DIR(cmd) == _IOC_READ)
 		memset(&buffer, 0, _IOC_SIZE(cmd));