Re: [PATCH v1 3/5] IB/uverbs: ex_query_device: answer must depend on response buffer's size

Hi,

Le jeudi 29 janvier 2015 à 11:38 -0700, Jason Gunthorpe a écrit :

On Thu, Jan 29, 2015 at 07:00:00PM +0100, Yann Droneaud wrote:

quoted

As specified in "Extending Verbs API" presentation [1] by Tzahi Oved
during OFA International Developer Workshop 2013, the request's
comp_mask should describe the request data: it's describe the
availability of extended fields in the request.
Conversely, the response's comp_mask should describe the presence
of extended fields in the response.

This makes sense to me as well.

quoted

-	err = ib_copy_to_udata(ucore, &resp, sizeof(resp));
+end:
+	err = ib_copy_to_udata(ucore, &resp, resp_len);
 	if (err)
 		return err;
 

I think resp_len should be returned, not 0?

As said previously it's not possible to use the effective size of the
response as the return value of the write() syscall: the syscall
must return the size of the input buffer, not the size of the output
buffer, otherwise it would break the semantics of the write() syscall.

Regards.

-- 
Yann Droneaud
OPTEYA


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