On Fri, 2011-03-25 at 19:44 +0100, Bart Van Assche wrote: > On Fri, Mar 25, 2011 at 4:06 PM, James Bottomley > <James.Bottomley@xxxxxxx> wrote: > > Explain first what lock inversion problems you see ... those usually > > only happen if you have the in the kernel upcall thread waiting for > > completion. > > In this context asynchronous upcalls have their problems too: the > in-kernel and the user space visible state may become inconsistent. > What will happen if processing of such notifications is delayed and > concurrently attempts are made from user space to act on these objects > ? I'm afraid that could result in horrible race conditions. What race conditions? The current exemplar is udev which uses the uevent mechanism. The usual way of coping with use before init is to key visibility off completion ... at least that's the way we do it in sysfs. James -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
