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    Subject[PATCH 4.4 07/20] target: Dont BUG_ON during NodeACL dynamic -> explicit conversion
    Date
    4.4-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Nicholas Bellinger <nab@linux-iscsi.org>

    commit 391e2a6de9781e4906dd7e0b1cc097050bf43e11 upstream.

    After the v4.2+ RCU conversion to se_node_acl->lun_entry_hlist,
    a BUG_ON() was added in core_enable_device_list_for_node() to
    detect when the located orig->se_lun_acl contains an existing
    se_lun_acl pointer reference.

    However, this scenario can happen when a dynamically generated
    NodeACL is being converted to an explicit NodeACL, when the
    explicit NodeACL contains a different LUN mapping than the
    default provided by the WWN endpoint.

    So instead of triggering BUG_ON(), go ahead and fail instead
    following the original pre RCU conversion logic.

    Reported-by: Benjamin ESTRABAUD <ben.estrabaud@mpstor.com>
    Cc: Benjamin ESTRABAUD <ben.estrabaud@mpstor.com>
    Reviewed-by: Christoph Hellwig <hch@lst.de>
    Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/target/target_core_device.c | 10 +++++++++-
    1 file changed, 9 insertions(+), 1 deletion(-)

    --- a/drivers/target/target_core_device.c
    +++ b/drivers/target/target_core_device.c
    @@ -362,7 +362,15 @@ int core_enable_device_list_for_node(
    kfree(new);
    return -EINVAL;
    }
    - BUG_ON(orig->se_lun_acl != NULL);
    + if (orig->se_lun_acl != NULL) {
    + pr_warn_ratelimited("Detected existing explicit"
    + " se_lun_acl->se_lun_group reference for %s"
    + " mapped_lun: %llu, failing\n",
    + nacl->initiatorname, mapped_lun);
    + mutex_unlock(&nacl->lun_entry_mutex);
    + kfree(new);
    + return -EINVAL;
    + }

    rcu_assign_pointer(new->se_lun, lun);
    rcu_assign_pointer(new->se_lun_acl, lun_acl);

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