> > > The use of /dev/sg* is still common practice, its invention predates > > > > The /dev/sg interface cannot do the locking. If you use /dev/sg you are > > Again, it doesn't have to. It can pass the locking operations to the > related block device driver.
No it can't. The driver has no idea what the locking rules are for arbitary command blocks send to arbitary devices. /dev/sg is a *raw* interface. You can send anything to anyone, and the locking rules for that are far too complex for a giant morass of kernel code to get added. The mess begins because you use /dev/sg and put it in a cdrom group instead of using SG_IO on the /dev/sr device. The mess continues because of the user of O_EXCL locking thus forcing re-open/close by HAL instead of fcntl based co-operative locking. The job of the kernel is not and never has been to anticipate and correct everything stupid someone tries to do in user space. As I said before the people wanting to arbitrate serial ports got this right in the mid 1970's your situation is not much more complicated, unless you persist in using /dev/sg - which yes does make it hard, but so does writing it in COBOL, or while standing on your head. And the solution to all three cases is the same *DONT DO IT* Alan - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/