• Steffen Maier's avatar
    SCSI: zfcp: status read buffers on first adapter open with link down · 8f425c63
    Steffen Maier authored
    commit 9edf7d75 upstream.
    
    Commit 64deb6ef
    "[SCSI] zfcp: Use status_read_buf_num provided by FCP channel"
    started using a value returned by the channel but only evaluated the value
    if the fabric link is up.
    Commit 8d88cf3f
    "[SCSI] zfcp: Update status read mempool"
    introduced mempool resizings based on the above value.
    On setting an FCP device online for the very first time since boot, a new
    zeroed adapter object is allocated. If the link is down, the number of
    status read requests remains zero. Since just the config data exchange is
    incomplete, we proceed with adapter open recovery. However, we
    unconditionally call mempool_resize with adapter->stat_read_buf_num == 0 in
    this case.
    
    This causes a kernel message "kernel BUG at mm/mempool.c:131!" in process
    "zfcperp<FCP-device-bus-ID>" with last function mempool_resize in Krnl PSW
    and zfcp_erp_thread in the Call Trace.
    
    Don't evaluate channel values which are invalid on link down. The number of
    status read requests is always valid, evaluated, and set to a positive
    minimum greater than zero. The adapter open recovery can proceed and the
    channel has status read buffers to inform us on a future link up event.
    While we are not aware of any other code path that could result in mempool
    resize attempts of size zero, we still also initialize the number of status
    read buffers to be posted to a static minimum number on adapter object
    allocation.
    Signed-off-by: default avatarSteffen Maier <maier@linux.vnet.ibm.com>
    Signed-off-by: default avatarJames Bottomley <JBottomley@Parallels.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    8f425c63
zfcp_aux.c 15.3 KB