libata: allocate ap separately from shost

Don't embed ap inside shost.  Allocate it separately and point it back
from shosts's hostdata.  This makes port allocation more flexible and
allows regular ATA and SAS share host alloc/init paths.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/ata/libata-core.c

@@ -5792,13 +5792,18 @@ static struct ata_port * ata_port_add(const struct ata_probe_ent *ent,
 		return NULL;
 	}
 
-	shost = scsi_host_alloc(ent->sht, sizeof(struct ata_port));
-	if (!shost)
+	ap = kzalloc(sizeof(struct ata_port), GFP_KERNEL);
+	if (!ap)
 		return NULL;
 
-	shost->transportt = &ata_scsi_transport_template;
+	shost = scsi_host_alloc(ent->sht, sizeof(struct ata_port *));
+	if (!shost) {
+		kfree(ap);
+		return NULL;
+	}
 
-	ap = ata_shost_to_port(shost);
+	*(struct ata_port **)&shost->hostdata[0] = ap;
+	shost->transportt = &ata_scsi_transport_template;
 
 	ata_port_init(ap, host, ent, port_no);
 	ata_port_init_shost(ap, shost);
@@ -5824,9 +5829,13 @@ static void ata_host_release(struct device *gendev, void *res)
 	for (i = 0; i < host->n_ports; i++) {
 		struct ata_port *ap = host->ports[i];
 
-		if (ap)
+		if (!ap)
+			continue;
+
+		if (ap->scsi_host)
 			scsi_host_put(ap->scsi_host);
 
+		kfree(ap);
 		host->ports[i] = NULL;
 	}
 

include/linux/libata.h

@@ -1231,7 +1231,7 @@ static inline void ata_pad_free(struct ata_port *ap, struct device *dev)
 
 static inline struct ata_port *ata_shost_to_port(struct Scsi_Host *host)
 {
-	return (struct ata_port *) &host->hostdata[0];
+	return *(struct ata_port **)&host->hostdata[0];
 }
 
 #endif /* __LINUX_LIBATA_H__ */