> > On 12 October 2026 11:41:34 BST, Zqiang <[email protected]> wrote: > > > > > When running the tasks-rude and srcu-atomic tests, the fwd_prog_tasks > > kthread is created because the default value of fwd_progress is 1. > > however, the two RCU flavors not support ->call(): > > > > 1. tasks-rude: commit b428a9de9bba ("rcutorture: Stop testing RCU Tasks > > Rude asynchronous APIs") removed .call and .cb_barrier from tasks-rude, > > but left the .cbflood_max = 50000. > > > > 2. srcu-atomic: srcu_torture_init_forbidden_apis() sets ->call to NULL > > for SRCU_READ_FLAVOR_ATOMIC runs, but leaves ->cbflood_max untouched. > > > > In both cases, the non-zero ->cbflood_max fools the check above into > > creating the fwd_prog_tasks kthreads, even though those kthreads cannot > > possibly carry out any forward-progress test: > > > > 1. The rcu_torture_fwd_prog_cr() returns immediately due to cur_ops->call > > is NULL: > > > > [ 68.022674] rcu_torture_fwd_prog_cr: No ->call(), so no > > forward-progress test 0 > > [ 129.462046] rcu_torture_fwd_prog_cr: No ->call(), so no > > forward-progress test 0 > > [ 190.902123] rcu_torture_fwd_prog_cr: No ->call(), so no > > forward-progress test 0 > > [ 252.343809] rcu_torture_fwd_prog_cr: No ->call(), so no > > forward-progress test 0 > > > > 2. The rcu_torture_fwd_prog_nr() is never even invoked, because its caller > > requires cur_ops->stall_dur, and neither tasks-rude nor srcu-atomic > > provide ->stall_dur (only rcu_ops does). > > > > Therefore, creating fwd_prog_tasks kthreads is pointless, this commit > > removes the .cbflood_max from tasks-rude and clears ->cbflood_max in the > > srcu_torture_init_forbidden_apis(). > > > > simple verification output: > > > > [ 3.062959][ T1] srcu-torture: rcu_torture_fwd_prog_init: Disabled, > > unsupported by RCU flavor under test > > [ 2.922323][ T1] tasks-rude-torture: rcu_torture_fwd_prog_init: > > Disabled, unsupported by RCU flavor under test > > > Fixes tag? > > This LGTM anyway so: > > Reviewed-by: Bradley Morgan <[email protected]>
Thanks for reviewed !! Thanks Zqiang > > > > > Signed-off-by: Zqiang <[email protected]> > > --- > > kernel/rcu/rcutorture.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c > > index 968343be4e0d..00db87256e78 100644 > > --- a/kernel/rcu/rcutorture.c > > +++ b/kernel/rcu/rcutorture.c > > @@ -723,6 +723,7 @@ static void srcu_torture_init_forbidden_apis(void) > > cur_ops->deferred_free = NULL; > > cur_ops->exp_current = NULL; > > cur_ops->start_gp_poll = NULL; > > + cur_ops->cbflood_max = 0; > > } > > > > static void srcu_torture_init(void) > > @@ -1250,7 +1251,6 @@ static struct rcu_torture_ops tasks_rude_ops = { > > .exp_sync = synchronize_rcu_tasks_rude, > > .gp_kthread_dbg = show_rcu_tasks_rude_gp_kthread, > > .get_gp_data = rcu_tasks_rude_get_gp_data, > > - .cbflood_max = 50000, > > .irq_capable = 1, > > .name = "tasks-rude" > > }; > > > --- Thanks! > "I'm not a very positive person" - Linus torvalds >
