Messages in this thread | | | Date | Wed, 22 Jan 2020 10:33:53 +1100 (AEDT) | From | Finn Thain <> | Subject | Re: [PATCH net v2 01/12] net/sonic: Add mutual exclusion for accessing shared state |
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On Tue, 21 Jan 2020, Eric Dumazet wrote:
> On 1/21/20 1:22 PM, Finn Thain 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> > > > @@ -284,9 +287,16 @@ static irqreturn_t sonic_interrupt(int irq, void *dev_id) > > struct net_device *dev = dev_id; > > struct sonic_local *lp = netdev_priv(dev); > > int status; > > + unsigned long flags; > > + > > + spin_lock_irqsave(&lp->lock, flags); > > > This is a hard irq handler, no need to block hard irqs. > > spin_lock() here is enough. >
Well, yes, assuming we're dealing with SMP [1]. Probably just disabling pre-emption is all that will ever be needed.
Anyway, the real problem solved by disabling irqs is that macsonic must avoid re-entrance of sonic_interrupt(). [2]
[1] https://lore.kernel.org/netdev/alpine.LNX.2.21.1.2001211026190.8@nippy.intranet/T/#m0523c8b2a26a410ed56889d9230c37ba1160d40a
[2] https://lore.kernel.org/netdev/alpine.LNX.2.21.1.2001211026190.8@nippy.intranet/T/#m1c8ca580d2b45e61a628d17839978d0bd5aaf061
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