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authorStefan Richter <stefanr@s5r6.in-berlin.de>2011-07-09 16:42:26 +0200
committerStefan Richter <stefanr@s5r6.in-berlin.de>2011-07-16 07:24:31 +0200
commitd873d794235efa590ab3c94d5ee22bb1fab19ac4 (patch)
tree6d65b61937517c475318b332b6e62f074df04d9b /drivers/firewire
parent9f426173e54a4f0882f9516c226f3165a3bd5474 (diff)
firewire: cdev: return -ENOTTY for unimplemented ioctls, not -EINVAL
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 <stefanr@s5r6.in-berlin.de> Cc: <stable@kernel.org>
Diffstat (limited to 'drivers/firewire')
-rw-r--r--drivers/firewire/core-cdev.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/firewire/core-cdev.c b/drivers/firewire/core-cdev.c
index b1c11775839..9b5915ebeb3 100644
--- 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));