• Steffen Maier's avatar
    [SCSI] zfcp: Do not wakeup while suspended · cb452149
    Steffen Maier authored
    If the mapping of FCP device bus ID and corresponding subchannel
    is modified while the Linux image is suspended, the resume of FCP
    devices can fail. During resume, zfcp gets callbacks from cio regarding
    the modified subchannels but they can be arbitrarily mixed with the
    restore/resume callback. Since the cio callbacks would trigger
    adapter recovery, zfcp could wakeup before the resume callback.
    Therefore, ignore the cio callbacks regarding subchannels while
    being suspended. We can safely do so, since zfcp does not deal itself
    with subchannels. For problem determination purposes, we still trace the
    ignored callback events.
    
    The following kernel messages could be seen on resume:
    
    kernel: <WWPN>: parent <FCP device bus ID> should not be sleeping
    
    As part of adapter reopen recovery, zfcp performs auto port scanning
    which can erroneously try to register new remote ports with
    scsi_transport_fc and the device core code complains about the parent
    (adapter) still sleeping.
    
    kernel: zfcp.3dff9c: <FCP device bus ID>:\
     Setting up the QDIO connection to the FCP adapter failed
    <last kernel message repeated 3 more times>
    kernel: zfcp.574d43: <FCP device bus ID>:\
     ERP cannot recover an error on the FCP device
    
    In such cases, the adapter gave up recovery and remained blocked along
    with its child objects: remote ports and LUNs/scsi devices. Even the
    adapter shutdown as part of giving up recovery failed because the ccw
    device state remained disconnected. Later, the corresponding remote
    ports ran into dev_loss_tmo. As a result, the LUNs were erroneously
    not available again after resume.
    
    Even a manually triggered adapter recovery (e.g. sysfs attribute
    failed, or device offline/online via sysfs) could not recover the
    adapter due to the remaining disconnected state of the corresponding
    ccw device.
    Signed-off-by: default avatarSteffen Maier <maier@linux.vnet.ibm.com>
    Cc: <stable@vger.kernel.org> #2.6.32+
    Signed-off-by: default avatarJames Bottomley <JBottomley@Parallels.com>
    cb452149
zfcp_ext.h 8.26 KB