This patch (as1276b) fixes two bugs in the SCSI target code and
explains an obscure requirement:
If we have to wait for an old target to disappear, instead of
calling flush_scheduled_work() the patch calls
schedule_timeout_uninterruptible(1). After all, whatever is
pinning the old target might not have anything to do with a
workqueue. Besides, flush_scheduled_work() is prone to
deadlocks and should never be used by drivers.
__scsi_add_device() called scsi_alloc_target() outside the
protection of the host's scan_mutex, meaning that it might
find an incompletely-initialized target or it might create
a duplicate target.
In scsi_sysfs_add_sdev(), the call to
transport_configure_device() for the target appears wrong,
since it will be called each time a device is added to the
target. But this is unavoidable for SPI, so a comment is
added to explain the situation.
Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
---
The revision gets rid of a bunch of changes which weren't really
needed. The remaining ones do seem to be necessary.
Index: usb-2.6/drivers/scsi/scsi_scan.c
===================================================================
--- usb-2.6.orig/drivers/scsi/scsi_scan.c
+++ usb-2.6/drivers/scsi/scsi_scan.c
@@ -376,6 +376,9 @@ static struct scsi_target *__scsi_find_t
*
* The target is returned with an incremented reference, so the caller
* is responsible for both reaping and doing a last put
+ *
+ * This routine should be called only under the protection of the host's
+ * scan_mutex.
*/
static struct scsi_target *scsi_alloc_target(struct device *parent,
int channel, uint id)
@@ -443,10 +446,12 @@ static struct scsi_target *scsi_alloc_ta
scsi_target_reap(starget);
return found_target;
}
- /* Unfortunately, we found a dying target; need to
- * wait until it's dead before we can get a new one */
+
+ /* Unfortunately, we found a dying target; we need to
+ * wait until it's gone before we can get a new one.
+ */
put_device(&found_target->dev);
- flush_scheduled_work();
+ schedule_timeout_uninterruptible(1);
goto retry;
}
@@ -1485,27 +1490,29 @@ static int scsi_report_lun_scan(struct s
struct scsi_device *__scsi_add_device(struct Scsi_Host *shost, uint channel,
uint id, uint lun, void *hostdata)
{
- struct scsi_device *sdev = ERR_PTR(-ENODEV);
+ struct scsi_device *sdev = ERR_PTR(-ENOMEM);
struct device *parent = &shost->shost_gendev;
- struct scsi_target *starget;
+ struct scsi_target *starget = NULL;
if (strncmp(scsi_scan_type, "none", 4) == 0)
return ERR_PTR(-ENODEV);
- starget = scsi_alloc_target(parent, channel, id);
- if (!starget)
- return ERR_PTR(-ENOMEM);
-
mutex_lock(&shost->scan_mutex);
if (!shost->async_scan)
scsi_complete_async_scans();
- if (scsi_host_scan_allowed(shost))
- scsi_probe_and_add_lun(starget, lun, NULL, &sdev, 1, hostdata);
+ if (scsi_host_scan_allowed(shost)) {
+ starget = scsi_alloc_target(parent, channel, id);
+ if (starget)
+ scsi_probe_and_add_lun(starget, lun, NULL, &sdev,
+ 1, hostdata);
+ }
mutex_unlock(&shost->scan_mutex);
- scsi_target_reap(starget);
- put_device(&starget->dev);
+ if (starget) {
+ scsi_target_reap(starget);
+ put_device(&starget->dev);
+ }
return sdev;
}
EXPORT_SYMBOL(__scsi_add_device);
Index: usb-2.6/drivers/scsi/scsi_sysfs.c
===================================================================
--- usb-2.6.orig/drivers/scsi/scsi_sysfs.c
+++ usb-2.6/drivers/scsi/scsi_sysfs.c
@@ -850,6 +850,9 @@ int scsi_sysfs_add_sdev(struct scsi_devi
if (error)
return error;
+ /* SPI requires a device before the transport can be configured,
+ * which prevents this call from being moved into scsi_target_add().
+ */
transport_configure_device(&starget->dev);
error = device_add(&sdev->sdev_gendev);
if (error) {
--
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
