On 08/21/05 23:52, Andrew Morton wrote: > James Bottomley <James.Bottomley@xxxxxxxxxxxx> wrote: > >>Since you won't post the usage code, just answer this: how does what >> you're doing with idr differ from its originally designed consumer: the >> posix timers which also do the idr_remove() in IRQ context? > > > erp. posix_timers has its own irq-safe lock, so we're doing extra, > unneeded locking in that code path. > > I think providing locking inside idr.c was always a mistake - generally we > rely on caller-provided locking for such things. Ahhh, *THANK YOU* Andrew for your common sense! Yes, James is unaware that 3 out of the 4 major entrances into IDR _must_ be synchronized with respect to each other, depending on your context (irq or not) *and* that that synchronization is external. If *one* of those 3 is done in IRQ context, then all three should be, since they should be synchnornized wrt each other. Only idr_pre_get() should not be called from IRQ context. *BUT* since idr_pre_get() and those other 3 may end up in the same _internally_ locked region, _that_ internally locked region should have the lowest common denominator lock, _because_ of the other 3 which have to be syncrhonised wrt each other. It is _this_ reason that the internal locking of IDR should use use the lowest common denominator because of the context of those other 3 which the _caller_ is responsible for synchronizing depending on the caller's context. Now James can we move on, please. Andrew, please integrate this patch. Thanks, Luben - : 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
