Re: [PATCH 01/12] target: Convert se_node_acl->device_list[] to RCU hlist

Nicholas A. Bellinger
2015-05-21T18:10:56Z

On Thu, 2015-05-21 at 19:03 +0200, Christoph Hellwig wrote:
> On Tue, May 19, 2015 at 08:22:31AM +0200, Christoph Hellwig wrote:
> > On Mon, May 18, 2015 at 11:05:47PM -0700, Nicholas A. Bellinger wrote:
> > > > [ 12.830576] kernel BUG at ../drivers/target/target_core_device.c:337!
> > > >
> > >
> > > How did you hit this..?
> >
> > tcm_node --block iblock_0/array /dev/sda
> >
> > line=$(tcm_loop --createnexus=0)
> > wwn=$(echo $line | awk '{print $15}')
> > tcm_loop --addlun=$wwn 0 0 iblock_0/array
>
> And here is the fix. Seems like anything using dynamic node ACLs was
> broken the same way (I could reproduce it with vhost as well).
>
> I don't really like how HBA_FLAGS_INTERNAL_USE means this is a virtual
> lun0, so I'll send another patch to replace it with a per-device flag
> eventually.
>
> ---
> From 9fd0e75cffde876b84b08952cc7f026d4e08d77a Mon Sep 17 00:00:00 2001
> From: Christoph Hellwig <hch@lst.de>
> Date: Thu, 21 May 2015 18:58:21 +0200
> Subject: target: don't add lun0 to tpg_lun_hlist
>
> We never want to find the virtual lun0 when looking up a lun on the TPG,
> otherwise the core code gets really confused.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> drivers/target/target_core_tpg.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/target/target_core_tpg.c b/drivers/target/target_core_tpg.c
> index b8c2a32..ced1dd6 100644
> --- a/drivers/target/target_core_tpg.c
> +++ b/drivers/target/target_core_tpg.c
> @@ -647,7 +647,8 @@ int core_tpg_add_lun(
>
> lun->lun_access = lun_access;
> lun->lun_status = TRANSPORT_LUN_STATUS_ACTIVE;
> - hlist_add_head_rcu(&lun->link, &tpg->tpg_lun_hlist);
> + if (!(dev->se_hba->hba_flags & HBA_FLAGS_INTERNAL_USE))
> + hlist_add_head_rcu(&lun->link, &tpg->tpg_lun_hlist);
>
> mutex_unlock(&tpg->tpg_lun_mutex);
>
> @@ -687,7 +688,8 @@ void core_tpg_remove_lun(
> }
>
> lun->lun_status = TRANSPORT_LUN_STATUS_FREE;
> - hlist_del_rcu(&lun->link);
> + if (!(dev->se_hba->hba_flags & HBA_FLAGS_INTERNAL_USE))
> + hlist_del_rcu(&lun->link);
> mutex_unlock(&tpg->tpg_lun_mutex);
>
> percpu_ref_exit(&lun->lun_ref);

Applied to for-next, and will squash into the original series soon.

--nab