• Nicholas Bellinger's avatar
    iscsi-target: Set session_fall_back_to_erl0 when forcing reinstatement · 197b806a
    Nicholas Bellinger authored
    While testing modification of per se_node_acl queue_depth forcing
    session reinstatement via lio_target_nacl_cmdsn_depth_store() ->
    core_tpg_set_initiator_node_queue_depth(), a hung task bug triggered
    when changing cmdsn_depth invoked session reinstatement while an iscsi
    login was already waiting for session reinstatement to complete.
    
    This can happen when an outstanding se_cmd descriptor is taking a
    long time to complete, and session reinstatement from iscsi login
    or cmdsn_depth change occurs concurrently.
    
    To address this bug, explicitly set session_fall_back_to_erl0 = 1
    when forcing session reinstatement, so session reinstatement is
    not attempted if an active session is already being shutdown.
    
    This patch has been tested with two scenarios.  The first when
    iscsi login is blocked waiting for iscsi session reinstatement
    to complete followed by queue_depth change via configfs, and
    second when queue_depth change via configfs us blocked followed
    by a iscsi login driven session reinstatement.
    
    Note this patch depends on commit d36ad77f to handle multiple
    sessions per se_node_acl when changing cmdsn_depth, and for
    pre v4.5 kernels will need to be included for stable as well.
    Reported-by: default avatarGary Guo <ghg@datera.io>
    Tested-by: default avatarGary Guo <ghg@datera.io>
    Cc: Gary Guo <ghg@datera.io>
    Cc: <stable@vger.kernel.org> # v4.1+
    Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
    197b806a
iscsi_target.c 126 KB