On Wed, 2015-08-12 at 10:10 -0700, Chris Leech wrote:
> Bump.
>
> We've done some testing, and this does prevent a deadlock that can be
> triggered with a session logout while other sessions on the same HBA
> are under high IO load. I'd be nice to see this merged.
so now it needs a tag for stable?
James
> - Chris
>
> On Tue, Jun 23, 2015 at 6:11 PM, John Soni Jose <sony.john@xxxxxxxxxxxxx> wrote:
> > Issue:
> > 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@xxxxxxxxxxxxxx>
> > ---
> > drivers/scsi/libiscsi.c | 25 ++-----------------------
> > 1 file changed, 2 insertions(+), 23 deletions(-)
> >
> > diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
> > index 8053f24..98d9bb6 100644
> > --- a/drivers/scsi/libiscsi.c
> > +++ b/drivers/scsi/libiscsi.c
> > @@ -2941,10 +2941,10 @@ void iscsi_conn_teardown(struct iscsi_cls_conn *cls_conn)
> > {
> > 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->frwd_lock);
> > conn->c_stage = ISCSI_CONN_CLEANUP_WAIT;
> > if (session->leadconn == conn) {
> > @@ -2956,28 +2956,6 @@ void iscsi_conn_teardown(struct iscsi_cls_conn *cls_conn)
> > }
> > spin_unlock_bh(&session->frwd_lock);
> >
> > - /*
> > - * 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);
> > - /*
> > - * force eh_abort() to unblock
> > - */
> > - wake_up(&conn->ehwait);
> > - }
> > -
> > /* flush queued up work because we free the connection below */
> > iscsi_suspend_tx(conn);
> >
> > @@ -2994,6 +2972,7 @@ void iscsi_conn_teardown(struct iscsi_cls_conn *cls_conn)
> > if (session->leadconn == conn)
> > session->leadconn = NULL;
> > spin_unlock_bh(&session->frwd_lock);
> > + mutex_unlock(&session->eh_mutex);
> >
> > iscsi_destroy_conn(cls_conn);
> > }
> > --
> > 1.8.3.1
> >
> > --
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