Re: [linux-usb-devel] USB/hal: USB open() broken? (USB CD burner underruns, USB HDD hard resets)

[Andreas Mohr <andim2@users.sourceforge.net>]

Hi,

On Wed, Jun 21, 2006 at 06:16:03PM +0200, Bodo Eggert wrote:
> On Wed, 21 Jun 2006, Alan Cox wrote:
> > Ar Mer, 2006-06-21 am 02:07 +0200, ysgrifennodd Bodo Eggert:
> 
> > > This does not work, since O_EXCL does not work:
> > > http://lkml.org/lkml/2006/2/5/137
> > 
> > It works fine. Its an advisory exclusive locking scheme which is
> > precisely what is needed and precisely how some vendors implement their
> > solution.
> 
> This will be as effective as "/var/lock/please-don't-touch-the-burner",
> and the lock is more portable ...

Indeed, until all(!) relevant apps specify the cooperative O_EXCL flag,
there will always be some trouble left somewhere...
And of course don't even dare trying to do a simply shell cat on the raw
I/O device during an ongoing burning operation, will you!?

Maybe it's better to (additionally?) go down the route of fixing up
low-level communication weaknesses (since it's been semi-confirmed that it's
an USB communication issue, see other thread part).
IMHO this is a severe user experience issue that shouldn't be fixed up
("covered", "hidden") by the O_EXCL thingy alone.

Andreas Mohr