Ah, the MSG_ORDERED_TASK did probably not exist when I originally did
the patch (a year or so ago, iirc). I'll change the define to follow the
rest of the code.
> A problem (that is probably only an issue for older drives) is that
> while technically the standard requires all 3 types of TAG to be
> supported if tag queueing is, some drives really only have simple tag
> support in their firmware, so you may need to add a blacklist for
> ordered tags on certain drives.
Yes you are right.
> A further issue is that you haven't added anything to the error
> recovery code for this. If error recovery is activated for the device
> at the reset level, all tags will be discarded by the device. The eh
> will retry the failing command and then the other tagged commands will
> be re-issued from the scsi_bottom_half_handler (assuming the low level
> device driver immediately fails them with DID_RESET) in the order in
> which the low level driver failed them. Thus you have potentially
> completely messed up the ordering when the commands all get retried.
I already have this fixed locally by just maintaining a fifo list of
queued commands so we can retry them in the correct order. For 2.5
there's a busy and free list (so no more scanning for a free command
either), I would imagine that the easiest for 2.4 is to just maintain a
busy list in addition to the current array of pending/free commands.
-- Jens Axboe- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/