3 files changed, 49 insertions, 18 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 05922e9f4fad..35b621293831 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -6453,7 +6453,7 @@ int ata_host_register(struct ata_host *host, struct scsi_host_template *sht)
         for (i = 0; i < host->n_ports; i++) {
                 struct ata_port *ap = host->ports[i];
 
-                ata_scsi_scan_host(ap);
+                ata_scsi_scan_host(ap, 1);
         }
 
         return 0;
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index cfde22da07ac..12ac0b511f79 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -2947,17 +2947,22 @@ int ata_scsi_add_hosts(struct ata_host *host, struct scsi_host_template *sht)
         return rc;
 }
 
-void ata_scsi_scan_host(struct ata_port *ap)
+void ata_scsi_scan_host(struct ata_port *ap, int sync)
 {
+        int tries = 5;
+        struct ata_device *last_failed_dev = NULL;
+        struct ata_device *dev;
         unsigned int i;
 
         if (ap->flags & ATA_FLAG_DISABLED)
                 return;
 
+ repeat:
         for (i = 0; i < ATA_MAX_DEVICES; i++) {
-                struct ata_device *dev = &ap->device[i];
                 struct scsi_device *sdev;
 
+                dev = &ap->device[i];
+
                 if (!ata_dev_enabled(dev) || dev->sdev)
                         continue;
 
@@ -2967,6 +2972,45 @@ void ata_scsi_scan_host(struct ata_port *ap)
                         scsi_device_put(sdev);
                 }
         }
+
+        /* If we scanned while EH was in progress or allocation
+         * failure occurred, scan would have failed silently.  Check
+         * whether all devices are attached.
+         */
+        for (i = 0; i < ATA_MAX_DEVICES; i++) {
+                dev = &ap->device[i];
+                if (ata_dev_enabled(dev) && !dev->sdev)
+                        break;
+        }
+        if (i == ATA_MAX_DEVICES)
+                return;
+
+        /* we're missing some SCSI devices */
+        if (sync) {
+                /* If caller requested synchrnous scan && we've made
+                 * any progress, sleep briefly and repeat.
+                 */
+                if (dev != last_failed_dev) {
+                        msleep(100);
+                        last_failed_dev = dev;
+                        goto repeat;
+                }
+
+                /* We might be failing to detect boot device, give it
+                 * a few more chances.
+                 */
+                if (--tries) {
+                        msleep(100);
+                        goto repeat;
+                }
+
+                ata_port_printk(ap, KERN_ERR, "WARNING: synchronous SCSI scan "
+                                "failed without making any progress,\n"
+                                "                  switching to async\n");
+        }
+
+        queue_delayed_work(ata_aux_wq, &ap->hotplug_task,
+                           round_jiffies_relative(HZ));
 }
 
 /**
@@ -3093,20 +3137,7 @@ void ata_scsi_hotplug(struct work_struct *work)
         }
 
         /* scan for new ones */
-        ata_scsi_scan_host(ap);
-
-        /* If we scanned while EH was in progress, scan would have
-         * failed silently.  Requeue if there are enabled but
-         * unattached devices.
-         */
-        for (i = 0; i < ATA_MAX_DEVICES; i++) {
-                struct ata_device *dev = &ap->device[i];
-                if (ata_dev_enabled(dev) && !dev->sdev) {
-                        queue_delayed_work(ata_aux_wq, &ap->hotplug_task,
-                                round_jiffies_relative(HZ));
-                        break;
-                }
-        }
+        ata_scsi_scan_host(ap, 0);
 
         DPRINTK("EXIT\n");
 }
diff --git a/drivers/ata/libata.h b/drivers/ata/libata.h
index ba17fc5f2e99..48836b22ce2f 100644
--- a/drivers/ata/libata.h
+++ b/drivers/ata/libata.h
@@ -112,7 +112,7 @@ static inline int ata_acpi_on_devcfg(struct ata_device *adev) { return 0; }
 /* libata-scsi.c */
 extern int ata_scsi_add_hosts(struct ata_host *host,
                               struct scsi_host_template *sht);
-extern void ata_scsi_scan_host(struct ata_port *ap);
+extern void ata_scsi_scan_host(struct ata_port *ap, int sync);
 extern int ata_scsi_offline_dev(struct ata_device *dev);
 extern void ata_scsi_hotplug(struct work_struct *work);
 extern unsigned int ata_scsiop_inq_std(struct ata_scsi_args *args, u8 *rbuf,