idpf: Acquire the lock before accessing the xn->salt

The transaction salt was being accessed before acquiring the
idpf_vc_xn_lock when idpf has to forward the virtchnl reply.

Fixes: 34c21fa ("idpf: implement virtchnl transaction manager")
Signed-off-by: Manoj Vishwanathan <manojvishy@google.com>
Signed-off-by: David Decotigny <decot@google.com>
Signed-off-by: Brian Vazquez <brianvv@google.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Pavan Kumar Linga <pavan.kumar.linga@intel.com>
Tested-by: Krishneil Singh <krishneil.k.singh@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

Author: Manoj Vishwanathan

drivers/net/ethernet/intel/idpf/idpf_virtchnl.c

@@ -612,14 +612,15 @@ idpf_vc_xn_forward_reply(struct idpf_adapter *adapter,
 		return -EINVAL;
 	}
 	xn = &adapter->vcxn_mngr->ring[xn_idx];
+	idpf_vc_xn_lock(xn);
 	salt = FIELD_GET(IDPF_VC_XN_SALT_M, msg_info);
 	if (xn->salt != salt) {
 		dev_err_ratelimited(&adapter->pdev->dev, "Transaction salt does not match (%02x != %02x)\n",
 				    xn->salt, salt);
+		idpf_vc_xn_unlock(xn);
 		return -EINVAL;
 	}
 
-	idpf_vc_xn_lock(xn);
 	switch (xn->state) {
 	case IDPF_VC_XN_WAITING:
 		/* success */