On Tue, 2017-09-12 at 13:14 -0700, Florian Fainelli wrote: > We can enter a deadlock situation because there is no sufficient protection > when ndo_get_stats64() runs in process context to guard against RX or TX NAPI > contexts running in softirq, this can lead to the following lockdep splat and > actual deadlock was experienced as well with an iperf session in the > background > and a while loop doing ifconfig + ethtool.
> So just remove the u64_stats_update_begin()/end() pair in ndo_get_stats64() > since it does not appear to be useful for anything. No inconsistency was > observed with either ifconfig or ethtool, global TX counts equal the sum of > per-queue TX counts on a 32-bit architecture. > > Fixes: 10377ba7673d ("net: systemport: Support 64bit statistics") > Signed-off-by: Florian Fainelli <f.faine...@gmail.com> > --- > drivers/net/ethernet/broadcom/bcmsysport.c | 3 --- > 1 file changed, 3 deletions(-) > > diff --git a/drivers/net/ethernet/broadcom/bcmsysport.c > b/drivers/net/ethernet/broadcom/bcmsysport.c > index a6572b51435a..c3c53f6cd9e6 100644 > --- a/drivers/net/ethernet/broadcom/bcmsysport.c > +++ b/drivers/net/ethernet/broadcom/bcmsysport.c > @@ -1735,11 +1735,8 @@ static void bcm_sysport_get_stats64(struct net_device > *dev, > stats->tx_packets += tx_packets; > } > > - /* lockless update tx_bytes and tx_packets */ > - u64_stats_update_begin(&priv->syncp); Yes, this u64_stats_update_begin()/u64_stats_update_end() is bogus But why do we even write on tx_bytes/tx_packets here ??? Seems very wrong anyway. (ethtool -S does not call bcm_sysport_get_stats64() to refresh them ) > stats64->tx_bytes = stats->tx_bytes; > stats64->tx_packets = stats->tx_packets; > - u64_stats_update_end(&priv->syncp); > > do { > start = u64_stats_fetch_begin_irq(&priv->syncp);