libata: make ata_print_id atomic

This variable is incremented from multiple contexts (module_init via
libata-lldds and the libsas discovery thread).  Make it atomic to head
off any chance of libsas and libata creating duplicate ids.
Acked-by: NJacek Danecki <jacek.danecki@intel.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

drivers/ata/libata-core.c

@@ -95,7 +95,7 @@ static unsigned int ata_dev_set_xfermode(struct ata_device *dev);
 static void ata_dev_xfermask(struct ata_device *dev);
 static unsigned long ata_dev_blacklisted(const struct ata_device *dev);
 
-unsigned int ata_print_id = 1;
+atomic_t ata_print_id = ATOMIC_INIT(1);
 
 struct ata_force_param {
 	const char	*name;
@@ -6029,7 +6029,7 @@ int ata_host_register(struct ata_host *host, struct scsi_host_template *sht)
 
 	/* give ports names and add SCSI hosts */
 	for (i = 0; i < host->n_ports; i++)
-		host->ports[i]->print_id = ata_print_id++;
+		host->ports[i]->print_id = atomic_inc_return(&ata_print_id);
 
 
 	/* Create associated sysfs transport objects  */

drivers/ata/libata-scsi.c

@@ -3843,7 +3843,7 @@ int ata_sas_async_port_init(struct ata_port *ap)
 	int rc = ap->ops->port_start(ap);
 
 	if (!rc) {
-		ap->print_id = ata_print_id++;
+		ap->print_id = atomic_inc_return(&ata_print_id);
 		__ata_port_probe(ap);
 	}
 
@@ -3867,7 +3867,7 @@ int ata_sas_port_init(struct ata_port *ap)
 	int rc = ap->ops->port_start(ap);
 
 	if (!rc) {
-		ap->print_id = ata_print_id++;
+		ap->print_id = atomic_inc_return(&ata_print_id);
 		rc = ata_port_probe(ap);
 	}
 

drivers/ata/libata.h

@@ -53,7 +53,7 @@ enum {
 	ATA_DNXFER_QUIET	= (1 << 31),
 };
 
-extern unsigned int ata_print_id;
+extern atomic_t ata_print_id;
 extern int atapi_passthru16;
 extern int libata_fua;
 extern int libata_noacpi;