• Mark Salyzyn's avatar
    [SCSI] pm8001: deficient responses to IO_XFER_ERROR_BREAK and IO_XFER_OPEN_RETRY_TIMEOUT · 5954d738
    Mark Salyzyn authored
    IO_XFER_ERROR_BREAK and IO_XFER_OPEN_RETRY_TIMEOUT are deficient of the
    required actions as outlined in the programming manual for the pm8001. Due to
    the overlapping code requirements of these recovery responses, we found it
    necessary to bundle them together into one patch.
    
    When a break is received during the command phase (ssp_completion), this is a
    result of a timeout or interruption on the bus. Logic suggests that we should
    retry the command.
    
    When a break is received during the data-phase (ssp_event), the task must be
    aborted on the target or it will retain a data-phase lock turning the target
    reticent to all future media commands yet will successfully respond to TUR,
    INQUIRY and ABORT leading eventually to target failure through several
    abort-cycle loops.
    
    The open retry interval is exceedingly short resulting in occasional target
    drop-off during expander resets or when targets push-back during bad-block
    remapping. Increased effective timeout from 130ms to 1.5 seconds for each try
    so as to trigger after the administrative inquiry/tur timeout in the scsi
    subsystem to keep error-recovery harmonics to a minimum.
    
    When an open retry timeout event is received, the action required by the
    targets is to issue an abort for the outstanding command then logic suggests
    we retry the command as this state is usually an indication of a credit block
    or busy condition on the target.
    
    We hijacked the pm8001_handle_event work queue handler so that it will handle
    task as an argument instead of device for the workers in support of the
    deferred handling outlined above.
    
    Moderate to Heavy bad-path testing on a 2.6.32 vintage kernel, compile-testing
    on scsi-misc-2.6 kernel ...
    Signed-off-by: default avatarMark Salyzyn <mark_salyzyn@xyratex.com>
    Acked-by: default avatarJack Wang <jack_wang@usish.com>
    Signed-off-by: default avatarJames Bottomley <JBottomley@Parallels.com>
    5954d738
pm8001_sas.c 33.3 KB