On Fri, 30 Jul 2010 10:32:34 -0700
Joe Eykholt <jeykholt@xxxxxxxxx> wrote:
> Hi All,
>
> I'm working on a target module for scsi_tgt to work with libfc / fcoe
> in Linux 2.6.33.5. I'm missing some step in handling completion of
> a request.
>
> After each Inquiry or READ operation, in the transfer_response
> callback I send the data and response and then call the (*done)()
> routine.
>
> I figure I must be missing something, because I get this WARNING:
>
> [ 271.521650] ------------[ cut here ]------------
> [ 271.521658] WARNING: at block/blk-core.c:1080 __blk_put_request+0x4f/0xbe()
> [ 271.521660] Hardware name: <snip>
> [ 271.521662] Modules linked in: libfc_tgt scsi_tgt nfs lockd nfs_acl auth_rpcgss autofs4 sunrpc ip6t_REJECT
> nf_conntrack_ipv6 ip6table_filter ip6_tables ipv6 dm_multipath uinput fnic libfcoe libfc enic i2c_i801
> iTCO_wdt serio_raw scsi_transport_fc iTCO_vendor_support pcspkr e1000e shpchp radeon ttm drm_kms_helper drm
> i2c_algo_bit i2c_core
> [ 271.521705] Pid: 2769, comm: scsi_tgtd/2 Tainted: G W 2.6.33.5-ftgt #9
> [ 271.521708] Call Trace:
> [ 271.521715] [<ffffffff811696ae>] ? __blk_put_request+0x4f/0xbe
> [ 271.521720] [<ffffffff81041462>] warn_slowpath_common+0x77/0xa4
> [ 271.521724] [<ffffffff8104149e>] warn_slowpath_null+0xf/0x11
> [ 271.521728] [<ffffffff811696ae>] __blk_put_request+0x4f/0xbe
> [ 271.521735] [<ffffffffa02b14b7>] scsi_host_put_command+0x52/0x80 [scsi_tgt]
> [ 271.521740] [<ffffffffa02b14e5>] ? scsi_tgt_cmd_destroy+0x0/0x3f [scsi_tgt]
> [ 271.521745] [<ffffffffa02b151f>] scsi_tgt_cmd_destroy+0x3a/0x3f [scsi_tgt]
> [ 271.521751] [<ffffffff810513a0>] worker_thread+0x131/0x1bd
> [ 271.521756] [<ffffffff81054bfc>] ? autoremove_wake_function+0x0/0x38
> [ 271.521760] [<ffffffff8105126f>] ? worker_thread+0x0/0x1bd
> [ 271.521764] [<ffffffff810547fe>] kthread+0x7d/0x85
> [ 271.521770] [<ffffffff810099a4>] kernel_thread_helper+0x4/0x10
> [ 271.521774] [<ffffffff81054781>] ? kthread+0x0/0x85
> [ 271.521779] [<ffffffff810099a0>] ? kernel_thread_helper+0x0/0x10
> [ 271.521782] ---[ end trace 096013af4d0a82a0 ]---
>
> It's this code in block/blk-core.c:
>
> void __blk_put_request(struct request_queue *q, struct request *req)
> {
> if (unlikely(!q))
> return;
> if (unlikely(--req->ref_count))
> return;
>
> elv_completed_request(q, req);
>
> /* this is a bio leak */
> WARN_ON(req->bio != NULL);
>
> ...
>
> So, what should I be doing to tell the block layer that the request is done?
> Or, is there something that scsi_tgt should be doing to disassociate the bio
> from the req?
Maybe we should call blk_end_request_all().
But I don't think that bio is leaked in our case. So setting req->bio
to NULL might be fine.
I can't access to my IBM POWER box now but I'll try later.
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