firewire: fw-sbp2: enforce a retry of __scsi_add_device if bus generation changed
fw-sbp2 is unable to reconnect while performing __scsi_add_device
because there is only a single workqueue thread context available for
both at the moment. This should be fixed eventually.
An actual failure of __scsi_add_device is easy to handle, but an
incomplete execution of __scsi_add_device with an sdev returned would
remain undetected and leave the SBP-2 target unusable.
Therefore we use a workaround: If there was a bus reset during
__scsi_add_device (i.e. during the SCSI probe), we remove the new sdev
immediately, log out, and attempt login and SCSI probe again.
Tested-by: Jarod Wilson <jwilson@redhat.com> (earlier version)
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
diff --git a/drivers/firewire/fw-sbp2.c b/drivers/firewire/fw-sbp2.c
index 323b03b..6d10934 100644
--- a/drivers/firewire/fw-sbp2.c
+++ b/drivers/firewire/fw-sbp2.c
@@ -762,22 +762,43 @@
sdev = __scsi_add_device(shost, 0, 0,
scsilun_to_int(&eight_bytes_lun), lu);
- if (IS_ERR(sdev)) {
- smp_rmb(); /* generation may have changed */
- generation = device->generation;
- smp_rmb(); /* node_id must not be older than generation */
+ /*
+ * FIXME: We are unable to perform reconnects while in sbp2_login().
+ * Therefore __scsi_add_device() will get into trouble if a bus reset
+ * happens in parallel. It will either fail or leave us with an
+ * unusable sdev. As a workaround we check for this and retry the
+ * whole login and SCSI probing.
+ */
- sbp2_send_management_orb(lu, device->node_id, generation,
- SBP2_LOGOUT_REQUEST, lu->login_id, NULL);
- /*
- * Set this back to sbp2_login so we fall back and
- * retry login on bus reset.
- */
- PREPARE_DELAYED_WORK(&lu->work, sbp2_login);
- } else {
- lu->sdev = sdev;
- scsi_device_put(sdev);
+ /* Reported error during __scsi_add_device() */
+ if (IS_ERR(sdev))
+ goto out_logout_login;
+
+ scsi_device_put(sdev);
+
+ /* Unreported error during __scsi_add_device() */
+ smp_rmb(); /* get current card generation */
+ if (generation != device->card->generation) {
+ scsi_remove_device(sdev);
+ goto out_logout_login;
}
+
+ /* No error during __scsi_add_device() */
+ lu->sdev = sdev;
+ goto out;
+
+ out_logout_login:
+ smp_rmb(); /* generation may have changed */
+ generation = device->generation;
+ smp_rmb(); /* node_id must not be older than generation */
+
+ sbp2_send_management_orb(lu, device->node_id, generation,
+ SBP2_LOGOUT_REQUEST, lu->login_id, NULL);
+ /*
+ * If a bus reset happened, sbp2_update will have requeued
+ * lu->work already. Reset the work from reconnect to login.
+ */
+ PREPARE_DELAYED_WORK(&lu->work, sbp2_login);
out:
sbp2_target_put(tgt);
}