David Miller [mailto:davem@xxxxxxxxxxxxx] > Sent: Sunday, January 25, 2015 2:44 PM [...] > What keeps rtl_start_rx() from running in parallel with > r8152_submit_rx(), or any other accessor of the RX agg->list? Forgive my poor English. I would try to describe them clearly. The steps about the rx agg->list would be 1. carrier on or autoresume occurs. 2. Call rtl_start_rx(). 3. Rx agg->list flows between device and tp->rx_done. 4. carrier off or autosuspend occurs. 5. call rtl_stop_rx(). The rtl_start_rx() would only be called when the linking status is changed from off to on or the auto resume occurs. And rtl_start_rx() would reinitialize the tp->rx_done and all of the rx agg->list. After step 2, the rx agg->list would flow between the usb host controller and the driver. If r8152_submit_rx() is success, the driver wouldn't own the rx agg->list until it is returned from the usb host controller. If r8152_submit_rx() is fail, the driver would still own the rx agg->list, and queue it to the tp->rx_done with spin lock for next try. If the status stays in step 3, only the rx_bottom() would submit the rx agg. The rtl_start_rx() wouldn't be called suddenly, unless the linking down or auto suspend occur first and linking on or auto resume occur again. If linking down or auto suspend occur, rtl_stop_rx() would be called (step 5). After this step, rx_bottom() wouldn't submit rx, and all rx agg->list would stop flowing. That is, the tp->rx_done and all rx agg->list wouldn't be changed until the next rtl_start_rx() is called. Therefore, the flow for each rx agg->list would be a. submittd by rtl_start_rx(). b. goto step c if success, otherwise goto step d. c. completed by usb host controller. d. queued to tp->rx_done with spin lock. e. dequeue from tp->rx_done with spin lock by rx_botoom(). f. goto step i if link down, otherwise goto step g. g. submitted by rx_botoom(). h. goto step b. i. goto step a if link on. And the patch change the step g to g1. g1. submitted by rx_botoom() if (!ret), otherwise goto step d. Best Regards, Hayes > > You also keep using different terminology from me when > discussing what lists do or do not need protection, and that > is going to make it difficult for anyone to follow our > conversation at all. > > We're talking specifically about RX agg->list objects and > whether access to them need synchronization or not. -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
