Re: [Libusb-devel] udev craze: need /dev/bus/usb rationale

[Greg KH <greg@kroah.com>]

On Mon, Feb 06, 2006 at 04:00:19PM -0800, Johannes Erdfelt wrote:
> On Mon, Feb 06, 2006, Greg KH <greg@kroah.com> wrote:
> > On Mon, Feb 06, 2006 at 03:29:41PM -0800, Johannes Erdfelt wrote:
> > > I'm working on implementing inotify support into libusb 1.0 right now.
> > 
> > Does usbfs support inotify events?  For some reason I didn't think it
> > did, but I'm probably wrong...
> 
> Well, it looks like it's trying to, but it's broken:
> 
> belushi:..otify-utils-0.25% ./inotify_test /proc/bus/usb/002
> inotify device fd = 3
> /proc/bus/usb/002 WD=1
> read = 32
> sizeof inotify_event = 16
> pevent->len = 16
> EVENT ON WD=1
> DELETE (file) 0x00000200
> FILENAME\x024
> 
> read = 32
> sizeof inotify_event = 16
> pevent->len = 16
> EVENT ON WD=1
> DELETE (file) 0x00000200
> FILENAME\x025
> 
> That was an unplug followed by a replug. This was with my test Keyspan
> serial device so there was a reset after the firmware was loaded. It
> looks like we're only receiving DELETE events, and no CREATE ones.
> It works correctly in /dev/bus/usb (which doesn't seem to create a
> device node when it loads firmware):

That's wierd that only the delete ones get sent and no others.

And the /dev/bus/usb stuff will always show up, as that is userspace
creating these files, not the kernel creating stuff underneath like the
usbfs files.

> belushi:..otify-utils-0.25% ./inotify_test /dev/bus/usb/2  
> inotify device fd = 3
> /dev/bus/usb/2 WD=1
> read = 32
> sizeof inotify_event = 16
> pevent->len = 16
> EVENT ON WD=1
> DELETE (file) 0x00000200
> FILENAME&
> 
> read = 32
> sizeof inotify_event = 16
> pevent->len = 16
> EVENT ON WD=1
> CREATE (file) 0x00000100
> FILENAME(
> 
> I had planned on using the old method of polling on
> /proc/bus/usb/devices for systems we use /proc/bus/usb anyway.

Maybe I should poke around and see how to get inotify working on libfs
based filesystems, I'm sure that sysfs could also use it...

thanks,

greg k-h


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