The patch titled
scsi: fix another crash at disconnect of usb strorage
has been added to the -mm tree. Its filename is
scsi-fix-another-crash-at-disconnect-of-usb-strorage.patch
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Subject: scsi: fix another crash at disconnect of usb strorage
From: Alexey Kuznetsov <kuznet@xxxxxxxxxxxxx>
Asynchronous scan (scsi_add_lun()) sets state to SDEV_RUNNING, but the
device is not registered in sysfs. Before async scan it was OK, because
before releasing scan_mutex old code called either scsi_sysfs_add_sdev()
or scsi_destroy_sdev() and, therefore, completed the work or discarded it.
With async scan the invariant is broken and scsi crashes in
__scsi_remove_device() when trying to unregister not registered devices.
The fix could be introducing new state(s), which is equivalent to
SDEV_RUNNING, except for one thing, we know that scsi_sysfs_add_sdev() has
not been called yet. Or a separate flag, because the state can be
SDEV_BLOCK or even something else.
Simpler way is just to check that the device is regstered in sysfs before
unregistering. Another operations in __scsi_remove_device() seem to be
idempotent or even required, because scsi_add_lun() makes some part of
work duplicated in scsi_sysfs_add_sdev().
Signed-off-by: Alexey Kuznetsov <kuznet@xxxxxxxxxxxxx>
Cc: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Denis V. Lunev <den@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
diff -puN drivers/scsi/scsi_sysfs.c~scsi-fix-another-crash-at-disconnect-of-usb-strorage drivers/scsi/scsi_sysfs.c
--- a/drivers/scsi/scsi_sysfs.c~scsi-fix-another-crash-at-disconnect-of-usb-strorage
+++ a/drivers/scsi/scsi_sysfs.c
@@ -965,9 +965,17 @@ void __scsi_remove_device(struct scsi_de
return;
bsg_unregister_queue(sdev->request_queue);
- device_unregister(&sdev->sdev_dev);
+ /* Asynchronous scan violates invariant that SDEV_RUNNING
+ * implies that device is registered in sysfs.
+ * We could introduce new state flag or extend set of state,
+ * but just plain checking that device is registered already
+ * before trying to unregister it is enough.
+ */
+ if (sdev->sdev_dev.kobj.parent)
+ device_unregister(&sdev->sdev_dev);
transport_remove_device(dev);
- device_del(dev);
+ if (dev->kobj.parent)
+ device_del(dev);
scsi_device_set_state(sdev, SDEV_DEL);
if (sdev->host->hostt->slave_destroy)
sdev->host->hostt->slave_destroy(sdev);
_
Patches currently in -mm which might be from kuznet@xxxxxxxxxxxxx are
scsi-fix-crash-when-disconnecting-usb-storage.patch
scsi-fix-another-crash-at-disconnect-of-usb-strorage.patch
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