On Wed, Nov 28, 2012 at 04:38:16PM -0800, Zach Brown wrote: > > We can't use cmpxchg() on the ring buffer's head pointer directly, since > > it's modded to nr_events and would be susceptible to ABA. So instead we > > maintain a shadow head that uses the full 32 bits, and cmpxchg() that > > and then updated the real head pointer. > > Time to update this comment to reflect the mutex instead of the shadow > head? :) Yeah :P > > + ev = kmap(page); > > + copy_ret = copy_to_user(event + ret, ev + pos, sizeof(*ev) * i); > > + kunmap(page); > > For lack of a better time: do we want to bring up the missing > flush_dcache_page() calls around the kernel mappings of ring pages that > are also mapped to user addresses? Well, it's mainly aio_complete() that needs to be doing flush_dcache_page()... technically io_getevents should be too, but only because it's updating the head pointer. Should probably do it now and not forget about it again, but I think it should be its own patch. > > prepare_to_wait_exclusive(&ctx->wait, &wait, > > TASK_INTERRUPTIBLE); > > > > + ret = aio_read_events(ctx, event + i, nr - i); > > + if (ret < 0) > > break; > > As mentioned offlist: we don't want to be blocking under > TASK_INTERRUPTIBLE. Is the plan to do a non-blocking check and pop > outside the wait loop to do a blocking copy? Argh. This thing is getting irritating. Gonna mull this over on irc more. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
