[SCSI] libfc: Remove the reference to FCP packet from scsi_cmnd in case of error

fc_queuecommand() allocates an FCP packet for each SCSI command and sends
it out on the wire. In the process it stores the reference to the FCP packet
in the scsi_cmnd structure.
Now, in case under stress testing the libfc exchange layer runs out of
exchanges the fc_queuecommand() may not be able to send out commands out on
the wire. In such a scenario if there is an error in sending the FCP packet
out the wire; fc_queuecommand() deletes the FCP packet from internal queue,
releases the FCP packet and returns a SCSI_MLQUEUE_HOST_BUSY status to the
scsi-ml. But, the reference to the FCP packet set in the scsi_cmnd is not
removed from the scsi_cmnd in this code path.

This might lead to a crash under stress testing where the scsi_cmnd failed by
fc_queuecommand() comes up to fc_eh_abort() via scsi eh thread. fc_eh_abort()
will get reference to the FCP packet to be aborted from the scsi_cmnd for
further FCP abort related processing and then try to release the FCP packet
that has already been released.

This patch removes the FCP packet reference from the scsi_cmnd before returning
back from fc_queuecommand() in case of an error in sending out the FCP packet.

Signed-off-by: Neerav Parikh <Neerav.Parikh@intel.com>
Tested-by: Ross Brattain <ross.b.brattain@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

diff --git a/drivers/scsi/libfc/fc_fcp.c b/drivers/scsi/libfc/fc_fcp.c
index 14dd1215de7f5bba1c67c2aa9ca2e7c57bc70005..afb63c843144b483c362794f72e41de8689d3358 100644 (file)
--- a/drivers/scsi/libfc/fc_fcp.c
+++ b/drivers/scsi/libfc/fc_fcp.c
@@ -1084,6 +1084,7 @@ static int fc_fcp_pkt_send(struct fc_lport *lport, struct fc_fcp_pkt *fsp)
        rc = lport->tt.fcp_cmd_send(lport, fsp, fc_fcp_recv);
        if (unlikely(rc)) {
                spin_lock_irqsave(&si->scsi_queue_lock, flags);
+               fsp->cmd->SCp.ptr = NULL;
                list_del(&fsp->list);
                spin_unlock_irqrestore(&si->scsi_queue_lock, flags);
        }