On 8/3/23 6:28 AM, Huang Cun wrote:
> When a disk fails to attach, the struct rdac_dh_data is released,
> but it is not removed from the ctlr->dh_list. When attaching another
> disk, the released rdac_dh_data will be accessed and the following
> BUG_ON() may be observed:
>
> [ 414.696167] scsi 5:0:0:7: rdac: Attach failed (8)
> ...
> [ 423.615364] kernel BUG at drivers/scsi/device_handler/scsi_dh_rdac.c:427!
> [ 423.615731] invalid opcode: 0000 [#1] SMP NOPTI
> ...
> [ 423.623247] Call Trace:
> [ 423.623598] rdac_bus_attach+0x203/0x4c0
> [ 423.623949] ? scsi_dh_handler_attach+0x2d/0x90
> [ 423.624300] scsi_dh_handler_attach+0x2d/0x90
> [ 423.624652] scsi_sysfs_add_sdev+0x88/0x270
> [ 423.625004] scsi_probe_and_add_lun+0xc47/0xd50
> [ 423.625354] scsi_report_lun_scan+0x339/0x3b0
> [ 423.625705] __scsi_scan_target+0xe9/0x220
> [ 423.626056] scsi_scan_target+0xf6/0x100
> [ 423.626404] fc_scsi_scan_rport+0xa5/0xb0
> [ 423.626757] process_one_work+0x15e/0x3f0
> [ 423.627106] worker_thread+0x4c/0x440
> [ 423.627453] ? rescuer_thread+0x350/0x350
> [ 423.627804] kthread+0xf8/0x130
> [ 423.628153] ? kthread_destroy_worker+0x40/0x40
> [ 423.628509] ret_from_fork+0x1f/0x40
>
> Fixes: 1a5dc166cd88 ("scsi_dh_rdac: update 'access_state' field")
> Signed-off-by: Huang Cun <huangcun@xxxxxxxxxxxxxx>
> Signed-off-by: Ding Hui <dinghui@xxxxxxxxxxxxxx>
> Cc: Donglin Peng <pengdonglin@xxxxxxxxxxxxxx>
> ---
> drivers/scsi/device_handler/scsi_dh_rdac.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/scsi/device_handler/scsi_dh_rdac.c b/drivers/scsi/device_handler/scsi_dh_rdac.c
> index c5538645057a..9d487c2b7708 100644
> --- a/drivers/scsi/device_handler/scsi_dh_rdac.c
> +++ b/drivers/scsi/device_handler/scsi_dh_rdac.c
> @@ -762,8 +762,10 @@ static int rdac_bus_attach(struct scsi_device *sdev)
>
> clean_ctlr:
> spin_lock(&list_lock);
> + list_del_rcu(&h->node);
> kref_put(&h->ctlr->kref, release_controller);
> spin_unlock(&list_lock);
> + synchronize_rcu();
>
Should this be:
spin_lock(&list_lock);
list_del_rcu(&h->node);
spin_unlock(&list_lock);
synchronize_rcu();
kref_put(&h->ctlr->kref, release_controller);
?
If you do the synchronize_rcu after the kref_put, then the kref_put
could free the rdac_dh_data, while check_ownership is still
accessing the rdac_dh_data, right?
