Date: Fri, 15 Feb 2008 21:29:02 +0100 (CET) From: Stefan Richter Subject: 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 (earlier version) Signed-off-by: Stefan Richter --- drivers/firewire/fw-sbp2.c | 51 ++++++++++++++++++++++++++----------- 1 file changed, 36 insertions(+), 15 deletions(-) Index: linux-2.6.25-rc1/drivers/firewire/fw-sbp2.c =================================================================== --- linux-2.6.25-rc1.orig/drivers/firewire/fw-sbp2.c +++ linux-2.6.25-rc1/drivers/firewire/fw-sbp2.c @@ -762,22 +762,43 @@ static void sbp2_login(struct work_struc 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); }