scsi: libfc: Handling of extra kref

Handling of extra kref which is done by lookup table in case rdata is
already present in list.

This issue was leading to memory leak. Trace from KMEMLEAK tool:

  unreferenced object 0xffff8888259e8780 (size 512):
    comm "kworker/2:1", pid 182614, jiffies 4433237386 (age 113021.971s)
    hex dump (first 32 bytes):
    58 0a ec cf 83 88 ff ff 00 00 00 00 00 00 00 00
    01 00 00 00 08 00 00 00 13 7d f0 1e 0e 00 00 10
  backtrace:
	[<000000006b25760f>] fc_rport_recv_req+0x3c6/0x18f0 [libfc]
	[<00000000f208d994>] fc_lport_recv_els_req+0x120/0x8a0 [libfc]
	[<00000000a9c437b8>] fc_lport_recv+0xb9/0x130 [libfc]
	[<00000000ad5be37b>] qedf_ll2_process_skb+0x73d/0xad0 [qedf]
	[<00000000e0eb6893>] process_one_work+0x382/0x6c0
	[<000000002dfd9e21>] worker_thread+0x57/0x5c0
	[<00000000b648204f>] kthread+0x1a0/0x1c0
	[<0000000072f5ab20>] ret_from_fork+0x35/0x40
	[<000000001d5c05d8>] 0xffffffffffffffff

Below is the log sequence which leads to memory leak. Here we get the
nested "Received PLOGI request" for same port and this request leads to
call the fc_rport_create() twice for the same rport.

	kernel: host1: rport fffce5: Received PLOGI request
	kernel: host1: rport fffce5: Received PLOGI in INIT state
	kernel: host1: rport fffce5: Port is Ready
	kernel: host1: rport fffce5: Received PRLI request while in state Ready
	kernel: host1: rport fffce5: PRLI rspp type 8 active 1 passive 0
	kernel: host1: rport fffce5: Received LOGO request while in state Ready
	kernel: host1: rport fffce5: Delete port
	kernel: host1: rport fffce5: Received PLOGI request
	kernel: host1: rport fffce5: Received PLOGI in state Delete - send busy

Link: https://lore.kernel.org/r/20200622101212.3922-2-jhasan@marvell.com
Reviewed-by: Girish Basrur <gbasrur@marvell.com>
Reviewed-by: Saurav Kashyap <skashyap@marvell.com>
Reviewed-by: Shyam Sundar <ssundar@marvell.com>
Signed-off-by: Javed Hasan <jhasan@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/libfc/fc_rport.c

@@ -133,8 +133,10 @@ struct fc_rport_priv *fc_rport_create(struct fc_lport *lport, u32 port_id)
 	lockdep_assert_held(&lport->disc.disc_mutex);
 
 	rdata = fc_rport_lookup(lport, port_id);
-	if (rdata)
+	if (rdata) {
+		kref_put(&rdata->kref, fc_rport_destroy);
 		return rdata;
+	}
 
 	if (lport->rport_priv_size > 0)
 		rport_priv_size = lport->rport_priv_size;