Re: [PATCH v1 01/14] xprtrdma: Transport fault injection

Anna Schumaker
2015-05-05T15:16:28Z

On 05/05/2015 11:15 AM, Chuck Lever wrote:
>
> On May 5, 2015, at 10:44 AM, Anna Schumaker <Anna.Schumaker-HgOvQuBEEgTQT0dZR+AlfA@public.gmane.org> wrote:
>
>> On 05/05/2015 09:53 AM, Chuck Lever wrote:
>>>
>>> On May 5, 2015, at 9:49 AM, Anna Schumaker <Anna.Schumaker-HgOvQuBEEgTQT0dZR+AlfA@public.gmane.org> wrote:
>>>
>>>> Hi Chuck,
>>>>
>>>> Neat idea! Are servers able to handle client recovery without getting too confused?
>>>
>>> So far I have encountered only issues on the client side. I think this
>>> is because the client is the active part of re-establishing transport
>>> connections. In addition, RPC/RDMA clients have a bunch of resources
>>> that need to be reset after a transport disconnect.
>>>
>>> I think this idea can be translated into something that can be done
>>> in the generic layer (ie, xprt.c) if people think that would be of
>>> benefit for testing TCP also.
>>
>> It might, and now is the time to discuss it before we're stuck maintaining multiple interfaces to the same thing.
>>
>> Another thought: can you move this under debugfs instead of proc? That's where the other kernel fault injection controls are, and it might give us a little more flexibility if we need to change the interface later.
>
> Something like /sys/kernel/debug/sunrpc/inject_transport_fault ?

That looks good to me! :)

Anna
>
>>
>> Anna
>>>
>>>
>>>> Anna
>>>>
>>>> On 05/04/2015 01:56 PM, Chuck Lever wrote:
>>>>> It has been exceptionally useful to exercise the logic that handles
>>>>> local immediate errors and RDMA connection loss. To enable
>>>>> developers to test this regularly and repeatably, add logic to
>>>>> simulate connection loss every so often.
>>>>>
>>>>> Fault injection is disabled by default. It is enabled with
>>>>>
>>>>> $ sudo echo xxx > /proc/sys/sunrpc/rdma_inject_transport_fault
>>>>>
>>>>> where "xxx" is a large positive number of transport method calls
>>>>> before a disconnect. A value of several thousand is usually a good
>>>>> number that allows reasonable forward progress while still causing a
>>>>> lot of connection drops.
>>>>>
>>>>> Signed-off-by: Chuck Lever <chuck.lever-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
>>>>> ---
>>>>> net/sunrpc/Kconfig | 12 ++++++++++++
>>>>> net/sunrpc/xprtrdma/transport.c | 34 ++++++++++++++++++++++++++++++++++
>>>>> net/sunrpc/xprtrdma/xprt_rdma.h | 1 +
>>>>> 3 files changed, 47 insertions(+)
>>>>>
>>>>> diff --git a/net/sunrpc/Kconfig b/net/sunrpc/Kconfig
>>>>> index 9068e72..329f82c 100644
>>>>> --- a/net/sunrpc/Kconfig
>>>>> +++ b/net/sunrpc/Kconfig
>>>>> @@ -61,6 +61,18 @@ config SUNRPC_XPRT_RDMA_CLIENT
>>>>>
>>>>> If unsure, say N.
>>>>>
>>>>> +config SUNRPC_XPRT_RDMA_FAULT_INJECTION
>>>>> + bool "RPC over RDMA client fault injection"
>>>>> + depends on SUNRPC_XPRT_RDMA_CLIENT
>>>>> + default N
>>>>> + help
>>>>> + This option enables fault injection in the xprtrdma module.
>>>>> + Fault injection is disabled by default. It is enabled with:
>>>>> +
>>>>> + $ sudo echo xxx > /proc/sys/sunrpc/rdma_inject_fault
>>>>> +
>>>>> + If unsure, say N.
>>>>> +
>>>>> config SUNRPC_XPRT_RDMA_SERVER
>>>>> tristate "RPC over RDMA Server Support"
>>>>> depends on SUNRPC && INFINIBAND && INFINIBAND_ADDR_TRANS
>>>>> diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
>>>>> index 54f23b1..fdcb2c7 100644
>>>>> --- a/net/sunrpc/xprtrdma/transport.c
>>>>> +++ b/net/sunrpc/xprtrdma/transport.c
>>>>> @@ -74,6 +74,7 @@ static unsigned int xprt_rdma_max_inline_write = RPCRDMA_DEF_INLINE;
>>>>> static unsigned int xprt_rdma_inline_write_padding;
>>>>> static unsigned int xprt_rdma_memreg_strategy = RPCRDMA_FRMR;
>>>>> int xprt_rdma_pad_optimize = 1;
>>>>> +static unsigned int xprt_rdma_inject_transport_fault;
>>>>>
>>>>> #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
>>>>>
>>>>> @@ -135,6 +136,13 @@ static struct ctl_table xr_tunables_table[] = {
>>>>> .mode = 0644,
>>>>> .proc_handler = proc_dointvec,
>>>>> },
>>>>> + {
>>>>> + .procname = "rdma_inject_transport_fault",
>>>>> + .data = &xprt_rdma_inject_transport_fault,
>>>>> + .maxlen = sizeof(unsigned int),
>>>>> + .mode = 0644,
>>>>> + .proc_handler = proc_dointvec,
>>>>> + },
>>>>> { },
>>>>> };
>>>>>
>>>>> @@ -246,6 +254,27 @@ xprt_rdma_connect_worker(struct work_struct *work)
>>>>> xprt_clear_connecting(xprt);
>>>>> }
>>>>>
>>>>> +#if defined CONFIG_SUNRPC_XPRT_RDMA_FAULT_INJECTION
>>>>> +static void
>>>>> +xprt_rdma_inject_disconnect(struct rpcrdma_xprt *r_xprt)
>>>>> +{
>>>>> + if (!xprt_rdma_inject_transport_fault)
>>>>> + return;
>>>>> +
>>>>> + if (atomic_dec_return(&r_xprt->rx_inject_count) == 0) {
>>>>> + atomic_set(&r_xprt->rx_inject_count,
>>>>> + xprt_rdma_inject_transport_fault);
>>>>> + pr_info("rpcrdma: injecting transport disconnect\n");
>>>>> + (void)rdma_disconnect(r_xprt->rx_ia.ri_id);
>>>>> + }
>>>>> +}
>>>>> +#else
>>>>> +static void
>>>>> +xprt_rdma_inject_disconnect(struct rpcrdma_xprt *r_xprt)
>>>>> +{
>>>>> +}
>>>>> +#endif
>>>>> +
>>>>> /*
>>>>> * xprt_rdma_destroy
>>>>> *
>>>>> @@ -405,6 +434,8 @@ xprt_setup_rdma(struct xprt_create *args)
>>>>> INIT_DELAYED_WORK(&new_xprt->rx_connect_worker,
>>>>> xprt_rdma_connect_worker);
>>>>>
>>>>> + atomic_set(&new_xprt->rx_inject_count,
>>>>> + xprt_rdma_inject_transport_fault);
>>>>> xprt_rdma_format_addresses(xprt);
>>>>> xprt->max_payload = new_xprt->rx_ia.ri_ops->ro_maxpages(new_xprt);
>>>>> if (xprt->max_payload == 0)
>>>>> @@ -515,6 +546,7 @@ xprt_rdma_allocate(struct rpc_task *task, size_t size)
>>>>> out:
>>>>> dprintk("RPC: %s: size %zd, request 0x%p\n", __func__, size, req);
>>>>> req->rl_connect_cookie = 0; /* our reserved value */
>>>>> + xprt_rdma_inject_disconnect(r_xprt);
>>>>> return req->rl_sendbuf->rg_base;
>>>>>
>>>>> out_rdmabuf:
>>>>> @@ -589,6 +621,7 @@ xprt_rdma_free(void *buffer)
>>>>> }
>>>>>
>>>>> rpcrdma_buffer_put(req);
>>>>> + xprt_rdma_inject_disconnect(r_xprt);
>>>>> }
>>>>>
>>>>> /*
>>>>> @@ -634,6 +667,7 @@ xprt_rdma_send_request(struct rpc_task *task)
>>>>>
>>>>> rqst->rq_xmit_bytes_sent += rqst->rq_snd_buf.len;
>>>>> rqst->rq_bytes_sent = 0;
>>>>> + xprt_rdma_inject_disconnect(r_xprt);
>>>>> return 0;
>>>>>
>>>>> failed_marshal:
>>>>> diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
>>>>> index 78e0b8b..08aee53 100644
>>>>> --- a/net/sunrpc/xprtrdma/xprt_rdma.h
>>>>> +++ b/net/sunrpc/xprtrdma/xprt_rdma.h
>>>>> @@ -377,6 +377,7 @@ struct rpcrdma_xprt {
>>>>> struct rpcrdma_create_data_internal rx_data;
>>>>> struct delayed_work rx_connect_worker;
>>>>> struct rpcrdma_stats rx_stats;
>>>>> + atomic_t rx_inject_count;
>>>>> };
>>>>>
>>>>> #define rpcx_to_rdmax(x) container_of(x, struct rpcrdma_xprt, rx_xprt)
>>>>>
>>>>> --
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>>>>
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>>>
>>> --
>>> Chuck Lever
>>> chuck[dot]lever[at]oracle[dot]com
>>>
>>>
>>>
>>
>
> --
> Chuck Lever
> chuck[dot]lever[at]oracle[dot]com