On 2018-07-30 15:48, Toke Høiland-Jørgensen wrote:

Rajkumar Manoharan [off-list ref] writes:

Hmm, the driver really shouldn't need to do any locking apart from 
using
the next_txq() API. But I think you are right that the seqno mechanism
doesn't play well with unserialised access to through next_txq() from
multiple CPUs. I'll see what I can do about that, and also incorporate
the other changes we've been discussing into a new RFC series.

Great.. :)

quoted

Hmm.. reorder_txq() API may not needed. Calling next_txq() takes care
of reordering list though the driver is accessing txqs directly.

Right, as long as the next_txq() path is still called even while
fetch_ind() is active, that should be fine.

I am still wondering how and when to refill deficit in case next_txq()
won't be called. :(

Will post RFC change on top of yours.

-Rajkumar