Messages in this thread | | | Date | Thu, 17 Mar 2022 15:12:17 +0530 | Subject | Re: [PATCH 4/4] rcu: Name internal polling flag | From | Neeraj Upadhyay <> |
| |
On 3/16/2022 8:12 PM, Frederic Weisbecker wrote: > Give a proper self-explanatory name to the expedited grace period > internal polling flag. > > Signed-off-by: Frederic Weisbecker <frederic@kernel.org> > Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> > Cc: Boqun Feng <boqun.feng@gmail.com> > Cc: Uladzislau Rezki <uladzislau.rezki@sony.com> > Cc: Joel Fernandes <joel@joelfernandes.org> > --- > kernel/rcu/rcu.h | 5 +++++ > kernel/rcu/tree.c | 2 +- > kernel/rcu/tree_exp.h | 9 +++++---- > 3 files changed, 11 insertions(+), 5 deletions(-) > > diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h > index eccbdbdaa02e..8a62bb416ba4 100644 > --- a/kernel/rcu/rcu.h > +++ b/kernel/rcu/rcu.h > @@ -30,6 +30,11 @@ > #define RCU_GET_STATE_USE_NORMAL 0x2 > #define RCU_GET_STATE_BAD_FOR_NORMAL (RCU_GET_STATE_FROM_EXPEDITED | RCU_GET_STATE_USE_NORMAL) > > +/* > + * Low-order bit definitions for polled grace-period internals. > + */ > +#define RCU_EXP_SEQ_POLL_DONE 0x1
From what I understood, this flag is intended for lifecycle management of the ->exp_seq_poll_rq; with the flag set meaning that we need to re-poll, which could be used for cases, where there is long gap between 2 polls, such that the sequence wraps around. So, maybe we can name it as RCU_EXP_SEQ_POLL_EXPIRED? However, my understanding could be wrong here.
Thanks Neeraj
> + > /* > * Return the counter portion of a sequence number previously returned > * by rcu_seq_snap() or rcu_seq_current(). > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > index 5da381a3cbe5..b3223b365f9f 100644 > --- a/kernel/rcu/tree.c > +++ b/kernel/rcu/tree.c > @@ -4679,7 +4679,7 @@ static void __init rcu_init_one(void) > spin_lock_init(&rnp->exp_lock); > mutex_init(&rnp->boost_kthread_mutex); > raw_spin_lock_init(&rnp->exp_poll_lock); > - rnp->exp_seq_poll_rq = 0x1; > + rnp->exp_seq_poll_rq = RCU_EXP_SEQ_POLL_DONE; > INIT_WORK(&rnp->exp_poll_wq, sync_rcu_do_polled_gp); > } > } > diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h > index c4a19c6a83cf..7ccb909d6355 100644 > --- a/kernel/rcu/tree_exp.h > +++ b/kernel/rcu/tree_exp.h > @@ -910,14 +910,14 @@ static void sync_rcu_do_polled_gp(struct work_struct *wp) > unsigned long s; > > s = READ_ONCE(rnp->exp_seq_poll_rq); > - if (s & 0x1) > + if (s & RCU_EXP_SEQ_POLL_DONE) > return; > while (!sync_exp_work_done(s)) > __synchronize_rcu_expedited(true); > raw_spin_lock_irqsave(&rnp->exp_poll_lock, flags); > s = rnp->exp_seq_poll_rq; > - if (!(s & 0x1) && sync_exp_work_done(s)) > - WRITE_ONCE(rnp->exp_seq_poll_rq, s | 0x1); > + if (!(s & RCU_EXP_SEQ_POLL_DONE) && sync_exp_work_done(s)) > + WRITE_ONCE(rnp->exp_seq_poll_rq, s | RCU_EXP_SEQ_POLL_DONE); > raw_spin_unlock_irqrestore(&rnp->exp_poll_lock, flags); > } > > @@ -946,7 +946,8 @@ unsigned long start_poll_synchronize_rcu_expedited(void) > rnp = rdp->mynode; > if (rcu_init_invoked()) > raw_spin_lock_irqsave(&rnp->exp_poll_lock, flags); > - if ((rnp->exp_seq_poll_rq & 0x1) || ULONG_CMP_LT(rnp->exp_seq_poll_rq, s)) { > + if ((rnp->exp_seq_poll_rq & RCU_EXP_SEQ_POLL_DONE) || > + ULONG_CMP_LT(rnp->exp_seq_poll_rq, s)) { > WRITE_ONCE(rnp->exp_seq_poll_rq, s); > if (rcu_init_invoked()) > queue_work(rcu_gp_wq, &rnp->exp_poll_wq);
| |