Re: [PATCH net] net: systemport: Fix 64-bit stats deadlock

On September 15, 2017 2:25:11 PM PDT, David Miller [off-list ref] wrote:

From: Florian Fainelli <f.fainelli@gmail.com>
Date: Tue, 12 Sep 2017 13:14:26 -0700

quoted

We can enter a deadlock situation because there is no sufficient

protection

quoted

when ndo_get_stats64() runs in process context to guard against RX or

TX NAPI

quoted

contexts running in softirq, this can lead to the following lockdep

splat and

quoted

actual deadlock was experienced as well with an iperf session in the

background

quoted

and a while loop doing ifconfig + ethtool.

...

quoted

So just remove the u64_stats_update_begin()/end() pair in

ndo_get_stats64()

quoted

since it does not appear to be useful for anything. No inconsistency

was

quoted

observed with either ifconfig or ethtool, global TX counts equal the

sum of

quoted

per-queue TX counts on a 32-bit architecture.

Fixes: 10377ba7673d ("net: systemport: Support 64bit statistics")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>

Applied.

FYI, there is another patch needed to ensure consistency between ethtool reported stats and netdevice stats, will submit that after some more testing. Thanks!

-- 
Florian