Re: [PATCH] b44: add 64 bit stats

On Thu, 2012-07-19 at 21:56 -0400, Kevin Groeneveld wrote:

I am still trying to make sure I understand this fully.  I want to
update some other drivers with 64 bit stats as well.  What you said
seems to make sense, but...

I was looking at the virtio_net.c driver.  One spot in this driver
which updates the stats is the receive_buf function.  recive_buf is
called from virtnet_poll which is registered as a napi poll function.
According to Documentation/networking/netdevices.txt the poll function
is called in a softirq context.  However, the function which reads the
stats uses u64_stats_fetch_begin/u64_stats_fetch_retry.  Shouldn't
this be u64_stats_fetch_begin_bh/u64_stats_fetch_retry_bh for the
exact reasons you described for my b44 patch?

Absolutely. You can argue that probably nobody use this driver on a
32bit UP machine, but technically speaking the current implementation is
racy.