Hi,
On Mon, May 10, 2021 at 09:52:06AM +0200, Greg KH wrote:
> On Sun, May 09, 2021 at 10:24:36AM +0200, Pavel Machek wrote:
> >
> > From: Mark Tomlinson <mark.tomlinson@xxxxxxxxxxxxxxxxxxx>
> >
> > commit 175e476b8cdf2a4de7432583b49c871345e4f8a1 upstream.
> >
> > When a new table value was assigned, it was followed by a write memory
> > barrier. This ensured that all writes before this point would complete
> > before any writes after this point. However, to determine whether the
> > rules are unused, the sequence counter is read. To ensure that all
> > writes have been done before these reads, a full memory barrier is
> > needed, not just a write memory barrier. The same argument applies when
> > incrementing the counter, before the rules are read.
> >
> > Changing to using smp_mb() instead of smp_wmb() fixes the kernel panic
> > reported in cc00bcaa5899 (which is still present), while still
> > maintaining the same speed of replacing tables.
> >
> > The smb_mb() barriers potentially slow the packet path, however testing
> > has shown no measurable change in performance on a 4-core MIPS64
> > platform.
> >
> > Fixes: 7f5c6d4f665b ("netfilter: get rid of atomic ops in fast path")
> > Signed-off-by: Mark Tomlinson <mark.tomlinson@xxxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
> > [Ported to stable, affected barrier is added by d3d40f237480abf3268956daf18cdc56edd32834 in mainline]
> > Signed-off-by: Pavel Machek (CIP) <pavel@xxxxxxx>
> > ---
> > include/linux/netfilter/x_tables.h | 2 +-
> > net/netfilter/x_tables.c | 3 +++
> > 2 files changed, 4 insertions(+), 1 deletion(-)
>
> What about 4.14 and 4.9? I can't take patches only for 4.4 that are not
> also in newer releases.
I have confirmed that this patch can be applied to 4.9 and 4.14.
Do I need resend this patch again?
>
> thanks,
>
> greg k-h
>
Best regards,
Nobuhiro
