[PATCH] libata: make sure sdev doesn't go away while rescanning

ata_scsi_dev_rescan() doesn't synchronize against SCSI device detach
and the target sdev might go away in the middle.  Fix it.

Signed-off-by: Tejun Heo <htejun@gmail.com>

1 files changed, 16 insertions, 4 deletions

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 7ff1adfc729c..d250858d201c 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -3181,15 +3181,27 @@ static int ata_scsi_user_scan(struct Scsi_Host *shost, unsigned int channel,
 void ata_scsi_dev_rescan(void *data)
 {
         struct ata_port *ap = data;
-        struct ata_device *dev;
+        unsigned long flags;
         unsigned int i;
 
+        spin_lock_irqsave(ap->lock, flags);
+
         for (i = 0; i < ATA_MAX_DEVICES; i++) {
-                dev = &ap->device[i];
+                struct ata_device *dev = &ap->device[i];
+                struct scsi_device *sdev = dev->sdev;
 
-                if (ata_dev_enabled(dev) && dev->sdev)
-                        scsi_rescan_device(&(dev->sdev->sdev_gendev));
+                if (!ata_dev_enabled(dev) || !sdev)
+                        continue;
+                if (scsi_device_get(sdev))
+                        continue;
+
+                spin_unlock_irqrestore(ap->lock, flags);
+                scsi_rescan_device(&(sdev->sdev_gendev));
+                scsi_device_put(sdev);
+                spin_lock_irqsave(ap->lock, flags);
         }
+
+        spin_unlock_irqrestore(ap->lock, flags);
 }
 
 /**