Dan Carpenter kindly reported:
<quote>
The patch d27a7cb919: "zfcp: trace on request for open and close of
WKA port" from Aug 10, 2016, leads to the following static checker
warning:
drivers/s390/scsi/zfcp_fsf.c:1615 zfcp_fsf_open_wka_port()
warn: 'req' was already freed.
drivers/s390/scsi/zfcp_fsf.c
1609 zfcp_fsf_start_timer(req, ZFCP_FSF_REQUEST_TIMEOUT);
1610 retval = zfcp_fsf_req_send(req);
1611 if (retval)
1612 zfcp_fsf_req_free(req);
^^^
Freed.
1613 out:
1614 spin_unlock_irq(&qdio->req_q_lock);
1615 if (req && !IS_ERR(req))
1616 zfcp_dbf_rec_run_wka("fsowp_1", wka_port, req->req_id);
^^^^^^^^^^^
Use after free.
1617 return retval;
1618 }
Same thing for zfcp_fsf_close_wka_port() as well.
</quote>
Rather than relying on req being NULL (or ERR_PTR) for all cases where
we don't want to trace or should not trace,
simply check retval which is unconditionally initialized with -EIO != 0
and it can only become 0 on successful retval = zfcp_fsf_req_send(req).
With that we can also remove the then again unnecessary unconditional
initialization of req which was introduced with that earlier commit.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Suggested-by: Benjamin Block <bblock@linux.vnet.ibm.com>
Signed-off-by: Steffen Maier <maier@linux.vnet.ibm.com>
Fixes: d27a7cb919 ("zfcp: trace on request for open and close of WKA port")
Cc: <stable@vger.kernel.org> #2.6.38+
Reviewed-by: Benjamin Block <bblock@linux.vnet.ibm.com>
Reviewed-by: Jens Remus <jremus@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2dfa6688aa