On Wed, 30 Mar 2022 13:52:17 +0900
Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote:
> On Tue, 29 Mar 2022 18:51:22 -0700
> Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx> wrote:
>
> > On Tue, Mar 29, 2022 at 6:41 PM Jakub Kicinski <kuba@xxxxxxxxxx> 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.
Sorry, please ignore this. Since the handler pointed by rh->handler never
be removed (unless removed by modules, but this will not happen while
the rethook is running), YES, WRITE_ONCE() is enough.
Please add below.
