netdev - Re: pull-request: bpf 2022-03-29

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Message-Id: <20220330135217.b6d0433831f2b3fa420458ae@kernel.org>
Date:   Wed, 30 Mar 2022 13:52:17 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Daniel Borkmann <daniel@...earbox.net>,
        Peter Zijlstra <peterz@...radead.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Andrii Nakryiko <andrii@...nel.org>,
        Network Development <netdev@...r.kernel.org>,
        bpf <bpf@...r.kernel.org>, Kernel Team <kernel-team@...com>
Subject: Re: pull-request: bpf 2022-03-29

On Tue, 29 Mar 2022 18:51:22 -0700
Alexei Starovoitov <alexei.starovoitov@...il.com> wrote:

> On Tue, Mar 29, 2022 at 6:41 PM Jakub Kicinski <kuba@...nel.org> wrote:
> >
> > On Tue, 29 Mar 2022 16:49:24 -0700 Alexei Starovoitov wrote:
> > > Hi David, hi Jakub,
> > >
> > > The following pull-request contains BPF updates for your *net* tree.
> > >
> > > We've added 16 non-merge commits during the last 1 day(s) which contain
> > > a total of 24 files changed, 354 insertions(+), 187 deletions(-).
> > >
> > > The main changes are:
> > >
> > > 1) x86 specific bits of fprobe/rethook, from Masami and Peter.
> > >
> > > 2) ice/xsk fixes, from Maciej and Magnus.
> > >
> > > 3) Various small fixes, from Andrii, Yonghong, Geliang and others.
> >
> > There are some new sparse warnings here that look semi-legit.
> > As in harmless but not erroneous.
> 
> Both are new warnings and not due to these patches, right?
> 
> > kernel/trace/rethook.c:68:9: error: incompatible types in comparison expression (different address spaces):
> > kernel/trace/rethook.c:68:9:    void ( [noderef] __rcu * )( ... )
> > kernel/trace/rethook.c:68:9:    void ( * )( ... )
> >
> > 66 void rethook_free(struct rethook *rh)
> > 67 {
> > 68         rcu_assign_pointer(rh->handler, NULL);
> > 69
> > 70         call_rcu(&rh->rcu, rethook_free_rcu);
> > 71 }
> >
> > Looks like this should be a WRITE_ONCE() ?
> 
> Masami, please take a look.

Yeah, I think we should make this rcu pointer (and read side must use rcu_dereference())
because this rh->handler becomes the key to disable this rethook.
Let me fix that.

Thanks,

-- 
Masami Hiramatsu <mhiramat@...nel.org>