Re: [PATCH 13/15] SUNRPC: RPC buffer size estimates are too large

[Chuck Lever <chuck.lever@oracle.com>]

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J. Bruce Fields wrote:
> On Wed, Jan 24, 2007 at 02:20:20PM -0500, Chuck Lever wrote:
>> @@ -753,25 +751,39 @@ call_reserveresult(struct rpc_task *task
>>  static void
>>  call_allocate(struct rpc_task *task)
>>  {
>> +	unsigned int slack = task->tk_auth->au_cslack;
>>  	struct rpc_rqst *req = task->tk_rqstp;
>>  	struct rpc_xprt *xprt = task->tk_xprt;
>> -	unsigned int	bufsiz;
>> +	struct rpc_procinfo *proc = task->tk_msg.rpc_proc;
>>  
>>  	dprint_status(task);
>>  
>> +	task->tk_status = 0;
>>  	task->tk_action = call_bind;
>> +
>>  	if (req->rq_buffer)
>>  		return;
>>  
>> -	/* FIXME: compute buffer requirements more exactly using
>> -	 * auth->au_wslack */
>> -	bufsiz = task->tk_msg.rpc_proc->p_bufsiz + RPC_SLACK_SPACE;
>> +	if (proc->p_proc != 0) {
>> +		BUG_ON(proc->p_arglen == 0);
>> +		if (proc->p_decode != NULL)
>> +			BUG_ON(proc->p_replen == 0);
>> +	}
>>  
>> -	req->rq_buffer = xprt->ops->buf_alloc(task, bufsiz << 1);
>> -	if (req->rq_buffer != NULL) {
>> -		req->rq_bufsize = bufsiz;
>> +	/*
>> +	 * Calculate the size (in quads) of the RPC call
>> +	 * and reply headers, and convert both values
>> +	 * to byte sizes.
>> +	 */
>> + 	req->rq_callsize = RPC_CALLHDRSIZE + (slack << 1) + proc->p_arglen;
>> + 	req->rq_callsize <<= 2;
>> + 	req->rq_rcvsize = RPC_REPHDRSIZE + slack + proc->p_replen;
>> + 	req->rq_rcvsize <<= 2;
> 
> What happened to rslack?  The callsize calculation should be using
> cslack and the rcvsize calculation rslack, I think, right?

As far as I understood it, cslack is the size of the authentication 
verifier for that flavor.  Shouldn't that be the same for calls and replies?

> In the krb5p case there's an extra annoyance: rslack is used to decide
> where to expect page data to start, so it can only take into account
> extra space needed at the beginning.  But krb5p has to add padding, for
> example, to the end of each request.

That padding has to follow XDR rules, though, correct?

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title:Principle Member of Staff
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version:2.1
end:vcard


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