[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH net-next v2 2/2] xen-netback: Grant copy the header instead of map and memcpy
On 01/04/14 12:40, Ian Campbell wrote: That original "++gop_map" assumed the header was also grant mapped, and incremented the pointer first here, which is wrong now.On Mon, 2014-03-31 at 16:08 +0100, Zoltan Kiss wrote:check_frags: - for (i = start; i < nr_frags; i++) { + for (i = 0; i < nr_frags; i++, gop_map++) { int j, newerr; pending_idx = frag_get_pending_idx(&shinfo->frags[i]); - tx_info = &vif->pending_tx_info[pending_idx]; /* Check error status: if okay then remember grant handle. */ - newerr = (++gop_map)->status; + newerr = (gop_map)->status;You've reworked the handling of gop_map and when and where it is incremented, which might be a legit cleanup but does it relate to the bulk of this change somehow that I'm missing? This is the only place at the moment when we do this, so I wouldn't bother to do it.[...] __skb_put(skb, data_len); + vif->tx_copy_ops[*copy_ops].source.u.ref = txreq.gref; + vif->tx_copy_ops[*copy_ops].source.domid = vif->domid; + vif->tx_copy_ops[*copy_ops].source.offset = txreq.offset; + + vif->tx_copy_ops[*copy_ops].dest.u.gmfn = + virt_to_mfn(skb->data); + vif->tx_copy_ops[*copy_ops].dest.domid = DOMID_SELF; + vif->tx_copy_ops[*copy_ops].dest.offset = + offset_in_page(skb->data); + + vif->tx_copy_ops[*copy_ops].len = data_len; + vif->tx_copy_ops[*copy_ops].flags = GNTCOPY_source_gref;We have gnttab_set_map_op. Should we have gnttap_set_copy_op too? The difference between gnttab_batch_map and gnttab_map_refs is that the latter calls set_foreign_p2m_mapping, which we need for sure. gnttab_batch_copy calls the hypercall and tries again if op->status == GNTST_eagain. I think that's exactly what we need here as well. The naming might be confusing indeed, but that should be the topic of an another patch.- BUG_ON(ret); + else { + gnttab_batch_copy(vif->tx_copy_ops, nr_cops); + if (nr_mops != 0) {if (nr_mops) would do.+ ret = gnttab_map_refs(vif->tx_map_ops,So we use gnttab_batch_copy and gnttab_map_refs. Shouldn't we either use gnttab_batch_copy and gnttab_batch_map or gnttab_copy gnttab_map_refs. (where gnttab_copy might be a bare GNTTABOP_copy or might be a helper wrapper). The point of the batch interface is to handle page unsharing etc, but doing it only for copies seems like a waste one way or another. Zoli _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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