[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>

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 7ff1adf..d250858 100644 (file)
--- 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);
 }
 
 /**