• Stefan Richter's avatar
    firewire: sbp2: parallelize login, reconnect, logout · 105e53f8
    Stefan Richter authored
    The struct sbp2_logical_unit.work items can all be executed in parallel
    but are not reentrant.  Furthermore, reconnect or re-login work must be
    executed in a WQ_MEM_RECLAIM workqueue.
    
    Hence replace the old single-threaded firewire-sbp2 workqueue by a
    concurrency-managed but non-reentrant workqueue with rescuer.
    firewire-core already maintains one, hence use this one.
    
    In earlier versions of this change, I observed occasional failures of
    parallel INQUIRY to an Initio INIC-2430 FireWire 800 to dual IDE bridge.
    More testing indicates that parallel INQUIRY is not actually a problem,
    but too quick successions of logout and login + INQUIRY, e.g. a quick
    sequence of cable plugout and plugin, can result in failed INQUIRY.
    This does not seem to be something that should or could be addressed by
    serialization.
    
    Another dual-LU device to which I currently have access to, an
    OXUF924DSB FireWire 800 to dual SATA bridge with firmware from MacPower,
    has been successfully tested with this too.
    
    This change is beneficial to environments with two or more FireWire
    storage devices, especially if they are located on the same bus.
    Management tasks that should be performed as soon and as quickly as
    possible, especially reconnect, are no longer held up by tasks on other
    devices that may take a long time, especially login with INQUIRY and sd
    or sr driver probe.
    Signed-off-by: default avatarStefan Richter <stefanr@s5r6.in-berlin.de>
    105e53f8
core.h 6.8 KB