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SubjectRe: [RFC PATCH 01/12] rcu: Implement rcu_segcblist_is_offloaded() config dependent
On Mon, Sep 21, 2020 at 02:43:40PM +0200, Frederic Weisbecker wrote:
> This simplify the usage of this API and avoid checking the kernel
> config from the callers.
>
> Suggested-by: Paul E. McKenney <paulmck@kernel.org>
> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
> Cc: Paul E. McKenney <paulmck@kernel.org>
> Cc: Josh Triplett <josh@joshtriplett.org>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
> Cc: Lai Jiangshan <jiangshanlai@gmail.com>
> Cc: Joel Fernandes <joel@joelfernandes.org>

Nice cleanup! I clearly should have done it this way to start with.

Any reason I shouldn't pull this into -rcu right now?

Thanx, Paul

> ---
> kernel/rcu/rcu_segcblist.h | 2 +-
> kernel/rcu/tree.c | 21 +++++++--------------
> 2 files changed, 8 insertions(+), 15 deletions(-)
>
> diff --git a/kernel/rcu/rcu_segcblist.h b/kernel/rcu/rcu_segcblist.h
> index 5c293afc07b8..492262bcb591 100644
> --- a/kernel/rcu/rcu_segcblist.h
> +++ b/kernel/rcu/rcu_segcblist.h
> @@ -62,7 +62,7 @@ static inline bool rcu_segcblist_is_enabled(struct rcu_segcblist *rsclp)
> /* Is the specified rcu_segcblist offloaded? */
> static inline bool rcu_segcblist_is_offloaded(struct rcu_segcblist *rsclp)
> {
> - return rsclp->offloaded;
> + return IS_ENABLED(CONFIG_RCU_NOCB_CPU) && rsclp->offloaded;
> }
>
> /*
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index 8ce77d9ac716..c0286ce8fc03 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -1583,8 +1583,7 @@ static bool __note_gp_changes(struct rcu_node *rnp, struct rcu_data *rdp)
> {
> bool ret = false;
> bool need_qs;
> - const bool offloaded = IS_ENABLED(CONFIG_RCU_NOCB_CPU) &&
> - rcu_segcblist_is_offloaded(&rdp->cblist);
> + const bool offloaded = rcu_segcblist_is_offloaded(&rdp->cblist);
>
> raw_lockdep_assert_held_rcu_node(rnp);
>
> @@ -2011,8 +2010,7 @@ static void rcu_gp_cleanup(void)
> needgp = true;
> }
> /* Advance CBs to reduce false positives below. */
> - offloaded = IS_ENABLED(CONFIG_RCU_NOCB_CPU) &&
> - rcu_segcblist_is_offloaded(&rdp->cblist);
> + offloaded = rcu_segcblist_is_offloaded(&rdp->cblist);
> if ((offloaded || !rcu_accelerate_cbs(rnp, rdp)) && needgp) {
> WRITE_ONCE(rcu_state.gp_flags, RCU_GP_FLAG_INIT);
> WRITE_ONCE(rcu_state.gp_req_activity, jiffies);
> @@ -2207,8 +2205,7 @@ rcu_report_qs_rdp(int cpu, struct rcu_data *rdp)
> unsigned long flags;
> unsigned long mask;
> bool needwake = false;
> - const bool offloaded = IS_ENABLED(CONFIG_RCU_NOCB_CPU) &&
> - rcu_segcblist_is_offloaded(&rdp->cblist);
> + const bool offloaded = rcu_segcblist_is_offloaded(&rdp->cblist);
> struct rcu_node *rnp;
>
> rnp = rdp->mynode;
> @@ -2375,8 +2372,7 @@ int rcutree_dead_cpu(unsigned int cpu)
> static void rcu_do_batch(struct rcu_data *rdp)
> {
> unsigned long flags;
> - const bool offloaded = IS_ENABLED(CONFIG_RCU_NOCB_CPU) &&
> - rcu_segcblist_is_offloaded(&rdp->cblist);
> + const bool offloaded = rcu_segcblist_is_offloaded(&rdp->cblist);
> struct rcu_head *rhp;
> struct rcu_cblist rcl = RCU_CBLIST_INITIALIZER(rcl);
> long bl, count;
> @@ -2620,8 +2616,7 @@ static __latent_entropy void rcu_core(void)
> unsigned long flags;
> struct rcu_data *rdp = raw_cpu_ptr(&rcu_data);
> struct rcu_node *rnp = rdp->mynode;
> - const bool offloaded = IS_ENABLED(CONFIG_RCU_NOCB_CPU) &&
> - rcu_segcblist_is_offloaded(&rdp->cblist);
> + const bool offloaded = rcu_segcblist_is_offloaded(&rdp->cblist);
>
> if (cpu_is_offline(smp_processor_id()))
> return;
> @@ -2919,8 +2914,7 @@ __call_rcu(struct rcu_head *head, rcu_callback_t func)
> rcu_segcblist_n_cbs(&rdp->cblist));
>
> /* Go handle any RCU core processing required. */
> - if (IS_ENABLED(CONFIG_RCU_NOCB_CPU) &&
> - unlikely(rcu_segcblist_is_offloaded(&rdp->cblist))) {
> + if (unlikely(rcu_segcblist_is_offloaded(&rdp->cblist))) {
> __call_rcu_nocb_wake(rdp, was_alldone, flags); /* unlocks */
> } else {
> __call_rcu_core(rdp, head, flags);
> @@ -3655,8 +3649,7 @@ static int rcu_pending(int user)
>
> /* Has RCU gone idle with this CPU needing another grace period? */
> if (!gp_in_progress && rcu_segcblist_is_enabled(&rdp->cblist) &&
> - (!IS_ENABLED(CONFIG_RCU_NOCB_CPU) ||
> - !rcu_segcblist_is_offloaded(&rdp->cblist)) &&
> + !rcu_segcblist_is_offloaded(&rdp->cblist) &&
> !rcu_segcblist_restempty(&rdp->cblist, RCU_NEXT_READY_TAIL))
> return 1;
>
> --
> 2.28.0
>

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