On Thu, Jan 09, 2020 at 01:52:41PM +0000, Burakov, Anatoly wrote:
> On 09-Jan-20 1:27 PM, Olivier Matz wrote:
> > To populate a mempool with a virtual area, the mempool code calls
> > rte_mempool_populate_iova() for each iova-contiguous area. It happens
> > (rarely) that this area is too small to store one object. In this case,
> > rte_mempool_populate_iova() returns an error, which is forwarded by
> > rte_mempool_populate_virt().
> >
> > This case should not throw an error in
> > rte_mempool_populate_virt(). Instead, the area that is too small should
> > just be ignored.
> >
> > To fix this issue, change the return value of
> > rte_mempool_populate_iova() to -ENOBUFS when no object can be populated,
> > so it can be ignored by the caller. As this would be an API change, add
> > a compat wrapper to keep the current API unchanged. The wrapper will be
> > removed for 20.11.
> >
> > Fixes: 354788b60cfd ("mempool: allow populating with unaligned virtual
> > area")
> > Cc: sta...@dpdk.org
> >
> > Signed-off-by: Olivier Matz <olivier.m...@6wind.com>
> > ---
> >
>
> The approach fixes the issue on my end, so
>
> Tested-by: Anatoly Burakov <anatoly.bura...@intel.com>
>
> > Is there a simple way to ensure that we won't forget to remove the
> > wrapper for 20.11? Anatoly suggested me to use versioned symbols, but
> > it's not clear to me how.
> >
>
> Yes, i'd like to do better than "ah shur we won't forget pinky swear".
>
> Can't we do this with ABI versioning? E.g.
>
> rte_populate_iova_v20() ... returns EINVAL
>
> rte_populate_iova_v21() ... returns ENOBUFS
>
> I'm pretty sure, even if it doesn't break, it will still be more likely to
> not be forgotten because there's almost a guarantee that someone will grep
> for symbol versioning macros across the codebase around 20.11 timeframe.
Without using symbol versionning, would this be ok too?
int
rte_mempool_populate_iova(struct rte_mempool *mp, char *vaddr,
rte_iova_t iova, size_t len, rte_mempool_memchunk_free_cb_t *free_cb,
void *opaque)
{
int ret;
ret = __rte_mempool_populate_iova(mp, vaddr, iova, len, free_cb,
opaque);
#if RTE_VERSION < RTE_VERSION_NUM(20, 11, 0, 0)
if (ret == -ENOBUFS)
ret = -EINVAL;
#endif
return ret;
}
> --
> Thanks,
> Anatoly
