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Commit 660d0831 authored by John Soni Jose's avatar John Soni Jose Committed by James Bottomley
Browse files

libiscsi: Fix host busy blocking during connection teardown 



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: default avatarJohn Soni Jose <sony.john@avagotech.com>
Reviewed-by: default avatarMike Christie <michaelc@cs.wisc.edu>
Reviewed-by: default avatarChris Leech <cleech@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarJames Bottomley <JBottomley@Odin.com>
parent 0c958ecc

drivers/scsi/libiscsi.c

+2 −23
Original line number Diff line number Diff line
@@ -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);

}