> On Sep 20, 2015, at 5:40 AM, Sagi Grimberg <[email protected]> wrote:
> 
> On 9/17/2015 11:46 PM, Chuck Lever wrote:
>> To support backward direction calls, I'm going to add an
>> svc_rdma_get_context() call in the client RDMA transport.
>> 
>> Called from ->buf_alloc(), we can't sleep waiting for memory.
>> So add an API that can get a server op_ctxt but won't sleep.
>> 
>> Signed-off-by: Chuck Lever <[email protected]>
>> ---
>>  include/linux/sunrpc/svc_rdma.h          |    2 ++
>>  net/sunrpc/xprtrdma/svc_rdma_transport.c |   28 +++++++++++++++++++++++-----
>>  2 files changed, 25 insertions(+), 5 deletions(-)
>> 
>> diff --git a/include/linux/sunrpc/svc_rdma.h 
>> b/include/linux/sunrpc/svc_rdma.h
>> index 6ce7495..2500dd1 100644
>> --- a/include/linux/sunrpc/svc_rdma.h
>> +++ b/include/linux/sunrpc/svc_rdma.h
>> @@ -224,6 +224,8 @@ extern void svc_rdma_send_error(struct svcxprt_rdma *, 
>> struct rpcrdma_msg *,
>>  extern int svc_rdma_post_recv(struct svcxprt_rdma *);
>>  extern int svc_rdma_create_listen(struct svc_serv *, int, struct sockaddr 
>> *);
>>  extern struct svc_rdma_op_ctxt *svc_rdma_get_context(struct svcxprt_rdma *);
>> +extern struct svc_rdma_op_ctxt *svc_rdma_get_context_gfp(struct 
>> svcxprt_rdma *,
>> +                                                     gfp_t);
>>  extern void svc_rdma_put_context(struct svc_rdma_op_ctxt *, int);
>>  extern void svc_rdma_unmap_dma(struct svc_rdma_op_ctxt *ctxt);
>>  extern struct svc_rdma_req_map *svc_rdma_get_req_map(void);
>> diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c 
>> b/net/sunrpc/xprtrdma/svc_rdma_transport.c
>> index 23aba30..c4083a3 100644
>> --- a/net/sunrpc/xprtrdma/svc_rdma_transport.c
>> +++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c
>> @@ -153,17 +153,35 @@ static void svc_rdma_bc_free(struct svc_xprt *xprt)
>>  }
>>  #endif      /* CONFIG_SUNRPC_BACKCHANNEL */
>> 
>> -struct svc_rdma_op_ctxt *svc_rdma_get_context(struct svcxprt_rdma *xprt)
>> +static void svc_rdma_init_context(struct svcxprt_rdma *xprt,
>> +                              struct svc_rdma_op_ctxt *ctxt)
>>  {
>> -    struct svc_rdma_op_ctxt *ctxt;
>> -
>> -    ctxt = kmem_cache_alloc(svc_rdma_ctxt_cachep,
>> -                            GFP_KERNEL | __GFP_NOFAIL);
>>      ctxt->xprt = xprt;
>>      INIT_LIST_HEAD(&ctxt->dto_q);
>>      ctxt->count = 0;
>>      ctxt->frmr = NULL;
>>      atomic_inc(&xprt->sc_ctxt_used);
>> +}
>> +
>> +struct svc_rdma_op_ctxt *svc_rdma_get_context_gfp(struct svcxprt_rdma *xprt,
>> +                                              gfp_t flags)
>> +{
>> +    struct svc_rdma_op_ctxt *ctxt;
>> +
>> +    ctxt = kmem_cache_alloc(svc_rdma_ctxt_cachep, flags);
>> +    if (!ctxt)
>> +            return NULL;
>> +    svc_rdma_init_context(xprt, ctxt);
>> +    return ctxt;
>> +}
>> +
>> +struct svc_rdma_op_ctxt *svc_rdma_get_context(struct svcxprt_rdma *xprt)
>> +{
> 
> Why not:
>       return svc_rdma_get_context_gfp(xprt, GFP_KERNEL | __GFP_NOFAIL);

The “if (!ctxt) return NULL;” is unneeded if __GFP_NOFAIL is
specified.

I’ll wait for additional comments on this one, I could go
either way.


> ?
> 
>> +    struct svc_rdma_op_ctxt *ctxt;
>> +
>> +    ctxt = kmem_cache_alloc(svc_rdma_ctxt_cachep,
>> +                            GFP_KERNEL | __GFP_NOFAIL);
>> +    svc_rdma_init_context(xprt, ctxt);
>>      return ctxt;
>>  }
>> 
>> 
>> --
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>> 
> 
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—
Chuck Lever



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