Re: [PATCH v1 02/14] xprtrdma: Warn when there are orphaned IB objects

Devesh Sharma
2015-05-06T14:22:03Z

On Wed, May 6, 2015 at 6:54 PM, Chuck Lever <chuck.lever-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org> wrote:
> Hi Devesh-
>
> On May 6, 2015, at 7:37 AM, Devesh Sharma <devesh.sharma-1wcpHE2jlwOV7V7JEmyr7g@public.gmane.orgm> wrote:
>
>> On Mon, May 4, 2015 at 11:27 PM, Chuck Lever <chuck.lever-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org> wrote:
>>>
>>> Print an error during transport destruction if ib_dealloc_pd()
>>> fails. This is a sign that xprtrdma orphaned one or more RDMA API
>>> objects at some point, which can pin lower layer kernel modules
>>> and cause shutdown to hang.
>>>
>>> Signed-off-by: Chuck Lever <chuck.lever-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
>>> ---
>>> net/sunrpc/xprtrdma/verbs.c | 4 ++--
>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
>>> index 4870d27..0cc4617 100644
>>> --- a/net/sunrpc/xprtrdma/verbs.c
>>> +++ b/net/sunrpc/xprtrdma/verbs.c
>>> @@ -710,8 +710,8 @@ rpcrdma_ia_close(struct rpcrdma_ia *ia)
>>> }
>>> if (ia->ri_pd != NULL && !IS_ERR(ia->ri_pd)) {
>>> rc = ib_dealloc_pd(ia->ri_pd);
>>> - dprintk("RPC: %s: ib_dealloc_pd returned %i\n",
>>> - __func__, rc);
>>
>> Should we check for EBUSY explicitly? other then this is an error in
>> vendor specific ib_dealloc_pd()
>
> Any error return means ib_dealloc_pd() has failed, right? Doesn’t that
> mean the PD is still allocated, and could cause problems later?

Yes, you are correct, I was thinking ib_dealloc_pd() has a refcount
implemented in the core layer, thus if the PD is used by any resource,
it will always fail with -EBUSY.
.With emulex adapter it is possible to fail dealloc_pd with ENOMEM or
EIO in cases where device f/w is not responding etc. this situation do
not represent PD is actually in use.

>
>
>>> + if (rc)
>>> + pr_warn("rpcrdma: ib_dealloc_pd status %i\n", rc);
>>> }
>>> }
>
> --
> Chuck Lever
> chuck[dot]lever[at]oracle[dot]com
>
>
>

--
-Regards
Devesh
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