Francois Romieu [mailto:rom...@fr.zoreil.com]
> Sent: Thursday, August 15, 2013 8:26 PM
> To: Hayeswang
> Cc: net...@vger.kernel.org; nic_swsd;
> linux-ker...@vger.kernel.org; linux-usb@vger.kernel.org; David Miller
> Subject: Re: [PATCH net-next v2 1/3] net/usb/r8152: support
> aggregation
>
[...]
> > +static
> > +int r8152_submit_rx(struct r8152 *tp, struct rx_agg *agg,
> gfp_t mem_flags);
> > +
>
> It's a new, less than 10 lines function without driver
> internal dependencies.
>
> The forward declaration is not needed.
The r8152_submit_rx() need the declaration of read_bulk_callback(), and the
read_bulk_callback() need the declaration of r8152_submit_rx(), too. It likes
a dead lock, so I have no idea how to do it without another declaration.
[...]
> > - if (!netif_device_present(netdev))
> > + if (!netif_carrier_ok(netdev))
> > return;
>
> How is it related to the subject of the patch ?
When link down, the driver would cancel all bulks. This avoid the re-submitting
bulk.
> [...]
> > +static void rx_bottom(struct r8152 *tp)
> > +{
> > + struct net_device_stats *stats;
> > + struct net_device *netdev;
> > + struct rx_agg *agg;
> > + struct rx_desc *rx_desc;
> > + unsigned long lockflags;
>
> Idiom: 'flags'.
>
> > + struct list_head *cursor, *next;
> > + struct sk_buff *skb;
> > + struct urb *urb;
> > + unsigned pkt_len;
> > + int len_used;
> > + u8 *rx_data;
> > + int ret;
>
> The scope of these variables is needlessly wide.
>
> > +
> > + netdev = tp->netdev;
> > +
> > + stats = rtl8152_get_stats(netdev);
> > +
> > + spin_lock_irqsave(&tp->rx_lock, lockflags);
> > + list_for_each_safe(cursor, next, &tp->rx_done) {
> > + list_del_init(cursor);
> > + spin_unlock_irqrestore(&tp->rx_lock, lockflags);
> > +
> > + agg = list_entry(cursor, struct rx_agg, list);
> > + urb = agg->urb;
> > + if (urb->actual_length < ETH_ZLEN) {
>
> goto submit;
>
> > + ret = r8152_submit_rx(tp, agg, GFP_ATOMIC);
> > + spin_lock_irqsave(&tp->rx_lock, lockflags);
> > + if (ret && ret != -ENODEV) {
> > + list_add_tail(&agg->list, next);
> > + tasklet_schedule(&tp->tl);
> > + }
> > + continue;
> > + }
>
> (remove the line above)
>
> [...]
> > + rx_data = rx_agg_align(rx_data + pkt_len + 4);
> > + rx_desc = (struct rx_desc *)rx_data;
> > + pkt_len = le32_to_cpu(rx_desc->opts1) &
> RX_LEN_MASK;
> > + len_used = (int)(rx_data - (u8 *)agg->head);
> > + len_used += sizeof(struct rx_desc) + pkt_len;
> > + }
> > +
>
> submit:
>
> > + ret = r8152_submit_rx(tp, agg, GFP_ATOMIC);
> > + spin_lock_irqsave(&tp->rx_lock, lockflags);
> > + if (ret && ret != -ENODEV) {
> > + list_add_tail(&agg->list, next);
> > + tasklet_schedule(&tp->tl);
> > + }
> > + }
> > + spin_unlock_irqrestore(&tp->rx_lock, lockflags);
> > +}
>
> It should be possible to retrieve more items in the spinlocked section
> so as to have a chance to batch more work. I have not thought
> too deeply
> about it.
I only lock when I want to remove or inser the agg list, and unlock as soon as
possible. I don't think I keep locking for a long time.
Best Regards,
Hayes
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