> 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? :) > + 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? > 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? - z -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
