On Thu, Nov 30, 2017 at 5:21 PM, Herbert Xu [off-list ref] wrote:

On Thu, Nov 30, 2017 at 05:15:16PM -0800, Tom Herbert wrote:

quoted

We don't need a guarantee of stability, but what I am seeing is that
we're consisitently dropping entries on when doing a multi-part
netlink walk. We start iterating over the table filling in the netlink
info. But eventually the netlink info fills up and returns an error.
netlink dump gets called again but now the iter of the table returns
the object following the one that would have overflowed the netlink
buffer. So the result I was seeing is that we dropped one object in in
each pass.

Thanks Tom! This information is very useful.

It sounds like this problem isn't specific to ila and would exist
for all rhashtable users that dump through netlink.  Let me think
about this a little bit more.

Right. Also note that the first patch is inspired by netlink dump
handling also. When we reach the end of the table (walk_next returns
NULL), we'll return a non-zero skb->len if some records have been
written to the buffer. On the next call to the dump we need to bounce
out immediately with zero length returned. Resetting the walker table
in walk start because it's NULL results in infinite loop if -EAGAIN is
ignored by the caller (rhashtable_walk_start returning void is nice
side effect of this).

Tom

Cheers,
--
Email: Herbert Xu [off-list ref]
Home Page: http://gondor.apana.org.au/~herbert/
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