On Wed, Aug 14, 2024 at 06:19:15PM +0530, Neeraj Upadhyay wrote:
> On Thu, Aug 01, 2024 at 05:43:03PM -0700, Paul E. McKenney wrote:
> > Currently, if the rcuscale module's async module parameter is specified
> > for RCU implementations that do not have sync primitives such as
> > call_rcu(), there will be a series of splats due to calls to a NULL
> > pointer. This commit therefore warns of this situation, but switches
> > to non-async testing.
> >
>
> I have changed this to below here [1]. Please let me know if I got it
> wrong.
>
> Currently, if the rcuscale module's async module parameter is specified
> for RCU implementations that do not have async primitives such as
> RCU Tasks Rude, there will be a series of splats due to calls to a NULL
> pointer. This commit therefore warns of this situation, but switches to
> non-async testing.
How about something like this, but perhaps wordsmithed a bit?
"Currently, if the rcuscale module's async module parameter
is specified for RCU implementations that do not have
async primitives such as RCU Tasks Rude (which now lacks
a call_rcu_tasks_rude() function), there will be a series of
splats due to calls to a NULL pointer. This commit therefore
warns of this situation, but switches to non-async testing."
Thanx, Paul
> [1]
> https://git.kernel.org/pub/scm/linux/kernel/git/neeraj.upadhyay/linux-rcu.git/commit/?h=next.14.08.24b&id=22d36840adbcab8fd826a7ca827fd60b708f03de
>
> - Neeraj
>
> > Signed-off-by: Paul E. McKenney <[email protected]>
> > ---
> > kernel/rcu/rcuscale.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/kernel/rcu/rcuscale.c b/kernel/rcu/rcuscale.c
> > index 933014b381ec0..315ced63ec105 100644
> > --- a/kernel/rcu/rcuscale.c
> > +++ b/kernel/rcu/rcuscale.c
> > @@ -525,7 +525,7 @@ rcu_scale_writer(void *arg)
> > schedule_timeout_idle(torture_random(&tr) %
> > writer_holdoff_jiffies + 1);
> > wdp = &wdpp[i];
> > *wdp = ktime_get_mono_fast_ns();
> > - if (gp_async) {
> > + if (gp_async && !WARN_ON_ONCE(!cur_ops->async)) {
> > retry:
> > if (!rhp)
> > rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
> > @@ -597,7 +597,7 @@ rcu_scale_writer(void *arg)
> > i++;
> > rcu_scale_wait_shutdown();
> > } while (!torture_must_stop());
> > - if (gp_async) {
> > + if (gp_async && cur_ops->async) {
> > cur_ops->gp_barrier();
> > }
> > writer_n_durations[me] = i_max + 1;
> > --
> > 2.40.1
> >
