[PATCH] oops in sd_shutdown

[Andries Brouwer <aebr@win.tue.nl>]

I see an Oops in the SCSI code, caused by the fact that sdkp is NULL
in sd_shutdown. "How can that be?", you will ask - dev->driver_data was set
in sd_probe. But in my case sd_probe never finished. An insmod usb-storage
hangs forever, or at least for more than six hours, giving ample opportunity
to observe this race between sd_probe and sd_shutdown.
(Of course sd_probe hangs in sd_revalidate disk.)

Perhaps the obvious test is a good idea.
Locking seems meaningless - sd_probe will never finish.

Andries

[Probably the init of usb_storage should start probing the devices in separate
threads, in parallel, and return immediately.]

The obvious patch (with whitespace damage)

diff -u --recursive --new-file -X /linux/dontdiff a/drivers/scsi/sd.c b/drivers/scsi/sd.c
--- a/drivers/scsi/sd.c Mon Jul 28 05:39:31 2003
+++ b/drivers/scsi/sd.c Tue Aug 12 01:24:51 2003
@@ -1351,10 +1351,14 @@
 static void sd_shutdown(struct device *dev)
 {
        struct scsi_device *sdp = to_scsi_device(dev);
-       struct scsi_disk *sdkp = dev_get_drvdata(dev);
+       struct scsi_disk *sdkp;
        struct scsi_request *sreq;
        int retries, res;
 
+       sdkp = dev_get_drvdata(dev);
+       if (!sdkp)
+               return;         /* this can happen */
+
        if (!sdp->online || !sdkp->WCE)
                return;