Re: [patch] svcrdma: endian bug in send_write_chunks()

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On 1/12/12 1:15 PM, Trond Myklebust wrote:
On Thu, 2012-01-12 at 11:21 -0500, J. Bruce Fields wrote:
On Thu, Jan 12, 2012 at 09:47:22AM +0300, Dan Carpenter wrote:
Sparse complains because arg_ch->rs_length is declared as network
endian but we're treating it as CPU endian.
This looks like it would actually change behavior on a little endian
architecture, so how did this work before?

> From some quick grepping, I see assignments both of the form

	...rs_length = ntohl(...)

and

	...rs_length = htonl(...)

but only see one declaration for a field named rs_length.

So my best guess would be that the code is ugly but working as is, and
needs cleanup by someone who knows how this field was intended to be
used.
It looks to me as if rs_handle and rs_offset are being similarly abused.
Basically, we need a serious clean up in svc_rdma_marshall.c to separate
out those variables that are in XDR-encoded form and those that are not.

The abuse is taking place because the marshal/unmarshall is being done in-place and it seemed wasteful at the time to add a chunk of memory to preserve the aesthetic. A union would 'work', but you still wouldn't 'know' whether the data was NBO or not by where it was -- which seems like the intent of the __beXX in the first place.

Tom

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