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    Subject[PATCH 3.2 023/107] libiscsi: Fix host busy blocking during connection teardown
    3.2.72-rc1 review patch.  If anyone has any objections, please let me know.

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

    From: John Soni Jose <sony.john@avagotech.com>

    commit 660d0831d1494a6837b2f810d08b5be092c1f31d upstream.

    In case of hw iscsi offload, an host can have N-number of active
    connections. There can be IO's running on some connections which
    make host->host_busy always TRUE. Now if logout from a connection
    is tried then the code gets into an infinite loop as host->host_busy
    is always TRUE.

    iscsi_conn_teardown(....)
    {
    .........
    /*
    * Block until all in-progress commands for this connection
    * time out or fail.
    */
    for (;;) {
    spin_lock_irqsave(session->host->host_lock, flags);
    if (!atomic_read(&session->host->host_busy)) { /* OK for ERL == 0 */
    spin_unlock_irqrestore(session->host->host_lock, flags);
    break;
    }
    spin_unlock_irqrestore(session->host->host_lock, flags);
    msleep_interruptible(500);
    iscsi_conn_printk(KERN_INFO, conn, "iscsi conn_destroy(): "
    "host_busy %d host_failed %d\n",
    atomic_read(&session->host->host_busy),
    session->host->host_failed);

    ................
    ...............
    }
    }

    This is not an issue with software-iscsi/iser as each cxn is a separate
    host.

    Fix:
    Acquiring eh_mutex in iscsi_conn_teardown() before setting
    session->state = ISCSI_STATE_TERMINATE.

    Signed-off-by: John Soni Jose <sony.john@avagotech.com>
    Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
    Reviewed-by: Chris Leech <cleech@redhat.com>
    Signed-off-by: James Bottomley <JBottomley@Odin.com>
    [bwh: Backported to 3.2: adjust context]
    Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    ---
    drivers/scsi/libiscsi.c | 25 ++-----------------------
    1 file changed, 2 insertions(+), 23 deletions(-)

    --- a/drivers/scsi/libiscsi.c
    +++ b/drivers/scsi/libiscsi.c
    @@ -2906,10 +2906,10 @@ void iscsi_conn_teardown(struct iscsi_cl
    {
    struct iscsi_conn *conn = cls_conn->dd_data;
    struct iscsi_session *session = conn->session;
    - unsigned long flags;

    del_timer_sync(&conn->transport_timer);

    + mutex_lock(&session->eh_mutex);
    spin_lock_bh(&session->lock);
    conn->c_stage = ISCSI_CONN_CLEANUP_WAIT;
    if (session->leadconn == conn) {
    @@ -2921,28 +2921,6 @@ void iscsi_conn_teardown(struct iscsi_cl
    }
    spin_unlock_bh(&session->lock);

    - /*
    - * Block until all in-progress commands for this connection
    - * time out or fail.
    - */
    - for (;;) {
    - spin_lock_irqsave(session->host->host_lock, flags);
    - if (!session->host->host_busy) { /* OK for ERL == 0 */
    - spin_unlock_irqrestore(session->host->host_lock, flags);
    - break;
    - }
    - spin_unlock_irqrestore(session->host->host_lock, flags);
    - msleep_interruptible(500);
    - iscsi_conn_printk(KERN_INFO, conn, "iscsi conn_destroy(): "
    - "host_busy %d host_failed %d\n",
    - session->host->host_busy,
    - session->host->host_failed);
    - /*
    - * force eh_abort() to unblock
    - */
    - wake_up(&conn->ehwait);
    - }
    -
    /* flush queued up work because we free the connection below */
    iscsi_suspend_tx(conn);

    @@ -2955,6 +2933,7 @@ void iscsi_conn_teardown(struct iscsi_cl
    if (session->leadconn == conn)
    session->leadconn = NULL;
    spin_unlock_bh(&session->lock);
    + mutex_unlock(&session->eh_mutex);

    iscsi_destroy_conn(cls_conn);
    }


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