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

Chuck Lever
2015-05-05T13:53:03Z

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.

> 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