>
> On Mon, Sep 08, 2025 at 08:31:55AM +0800, Zqiang wrote:
>
> >
> > Currently, the srcu_gp_start_if_needed() is always be invoked in
> > preempt disable's critical section, this commit therefore remove
> > redundant preempt_disable/enable() in srcu_gp_start_if_needed().
> >
> > Fixes: 65b4a59557f6 ("srcu: Make Tiny SRCU explicitly disable preemption")
> > Signed-off-by: Zqiang <[email protected]>
> >
> Looks good, but what would be a good way to make this code defend itself
> against being invoked from someplace else that did have preemption
> enabled? Especially given that the Tree SRCU version of this function
> does get invoked with preemption enabled?
ok, maybe we can add lockdep_assert_preemption_disabled() in
the srcu_gp_start_if_needed() ?
Thanks
Zqiang
>
> Thanx, Paul
>
> >
> > ---
> > kernel/rcu/srcutiny.c | 3 ---
> > 1 file changed, 3 deletions(-)
> >
> > diff --git a/kernel/rcu/srcutiny.c b/kernel/rcu/srcutiny.c
> > index b52ec45698e8..417bd0e4457c 100644
> > --- a/kernel/rcu/srcutiny.c
> > +++ b/kernel/rcu/srcutiny.c
> > @@ -181,10 +181,8 @@ static void srcu_gp_start_if_needed(struct
> > srcu_struct *ssp)
> > {
> > unsigned long cookie;
> >
> > - preempt_disable(); // Needed for PREEMPT_LAZY
> > cookie = get_state_synchronize_srcu(ssp);
> > if (ULONG_CMP_GE(READ_ONCE(ssp->srcu_idx_max), cookie)) {
> > - preempt_enable();
> > return;
> > }
> > WRITE_ONCE(ssp->srcu_idx_max, cookie);
> > @@ -194,7 +192,6 @@ static void srcu_gp_start_if_needed(struct srcu_struct
> > *ssp)
> > else if (list_empty(&ssp->srcu_work.entry))
> > list_add(&ssp->srcu_work.entry, &srcu_boot_list);
> > }
> > - preempt_enable();
> > }
> >
> > /*
> > --
> > 2.48.1
> >
>
