On Thu, Apr 27, 2023 at 4:28 PM Namhyung Kim <namhyung@xxxxxxxxx> wrote:
>
> On Thu, Apr 27, 2023 at 3:15 PM Andrii Nakryiko
> <andrii.nakryiko@xxxxxxxxx> wrote:
> > Ok, I didn't manage to force compiler to behave as long as
> > `&rq_old->lock` pattern was used. So I went for a different approach.
> > This works:
>
> Thanks! It works for me too!
>
> Can I use this patch with your Co-developed-by tag ?
of course
>
> Thanks,
> Namhyung
>
>
> >
> > $ git diff
> > diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c
> > b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> > index 8911e2a077d8..8d3cfbb3cc65 100644
> > --- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
> > +++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
> > @@ -418,32 +418,32 @@ int contention_end(u64 *ctx)
> >
> > extern struct rq runqueues __ksym;
> >
> > -struct rq__old {
> > +struct rq___old {
> > raw_spinlock_t lock;
> > } __attribute__((preserve_access_index));
> >
> > -struct rq__new {
> > +struct rq___new {
> > raw_spinlock_t __lock;
> > } __attribute__((preserve_access_index));
> >
> > SEC("raw_tp/bpf_test_finish")
> > int BPF_PROG(collect_lock_syms)
> > {
> > - __u64 lock_addr;
> > + __u64 lock_addr, lock_off;
> > __u32 lock_flag;
> >
> > + if (bpf_core_field_exists(struct rq___new, __lock))
> > + lock_off = offsetof(struct rq___new, __lock);
> > + else
> > + lock_off = offsetof(struct rq___old, lock);
> > +
> > for (int i = 0; i < MAX_CPUS; i++) {
> > struct rq *rq = bpf_per_cpu_ptr(&runqueues, i);
> > - struct rq__new *rq_new = (void *)rq;
> > - struct rq__old *rq_old = (void *)rq;
> >
> > if (rq == NULL)
> > break;
> >
> > - if (bpf_core_field_exists(rq_new->__lock))
> > - lock_addr = (__u64)&rq_new->__lock;
> > - else
> > - lock_addr = (__u64)&rq_old->lock;
> > + lock_addr = (__u64)(void *)rq + lock_off;
> > lock_flag = LOCK_CLASS_RQLOCK;
> > bpf_map_update_elem(&lock_syms, &lock_addr,
> > &lock_flag, BPF_ANY);
> > }
> >
> >
> > > Thanks,
> > > Namhyung
> > >
> > >
