Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Mon, 20 Jan 2020 09:29:14 +0100 | Subject | Re: [PATCH net 04/19] net/sonic: Add mutual exclusion for accessing shared state |
| |
Hi Finn,
On Mon, Jan 20, 2020 at 12:19 AM Finn Thain <fthain@telegraphics.com.au> wrote: > The netif_stop_queue() call in sonic_send_packet() races with the > netif_wake_queue() call in sonic_interrupt(). This causes issues > like "NETDEV WATCHDOG: eth0 (macsonic): transmit queue 0 timed out". > Fix this by disabling interrupts when accessing tx_skb[] and next_tx. > Update a comment to clarify the synchronization properties. > > Fixes: efcce839360f ("[PATCH] macsonic/jazzsonic network drivers update") > Tested-by: Stan Johnson <userm57@yahoo.com> > Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Thanks for your patch!
> --- a/drivers/net/ethernet/natsemi/sonic.c > +++ b/drivers/net/ethernet/natsemi/sonic.c > @@ -242,7 +242,7 @@ static void sonic_tx_timeout(struct net_device *dev) > * wake the tx queue > * Concurrently with all of this, the SONIC is potentially writing to > * the status flags of the TDs. > - * Until some mutual exclusion is added, this code will not work with SMP. However, > + * A spin lock is needed to make this work on SMP platforms. However, > * MIPS Jazz machines and m68k Macs were all uni-processor machines. > */ > > @@ -252,6 +252,7 @@ static int sonic_send_packet(struct sk_buff *skb, struct net_device *dev) > dma_addr_t laddr; > int length; > int entry; > + unsigned long flags; > > netif_dbg(lp, tx_queued, dev, "%s: skb=%p\n", __func__, skb); > > @@ -273,6 +274,8 @@ static int sonic_send_packet(struct sk_buff *skb, struct net_device *dev) > return NETDEV_TX_OK; > } > > + local_irq_save(flags); > +
Wouldn't it be better to use a spinlock instead? It looks like all currently supported platforms (Mac, Jazz, and XT2000) do no support SMP, but I'm not 100% sure about the latter. And this generic sonic.c core may end up being used on other platforms that do support SMP.
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
| |