call_rcu_core is only called from __call_rcu_common with interrupt
disabled. This patch thus removes the unreachable logic and the would-be
unused 'flags' parameter.
Signed-off-by: Alan Huang <[email protected]>
---
kernel/rcu/tree.c | 35 ++---------------------------------
1 file changed, 2 insertions(+), 33 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index d5507ac1bbf1..b0ea2ebd7769 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2983,7 +2983,7 @@ static void rcutree_enqueue(struct rcu_data *rdp, struct rcu_head *head, rcu_cal
* Handle any core-RCU processing required by a call_rcu() invocation.
*/
static void call_rcu_core(struct rcu_data *rdp, struct rcu_head *head,
- rcu_callback_t func, unsigned long flags)
+ rcu_callback_t func)
{
rcutree_enqueue(rdp, head, func);
/*
@@ -2992,37 +2992,6 @@ static void call_rcu_core(struct rcu_data *rdp, struct rcu_head *head,
*/
if (!rcu_is_watching())
invoke_rcu_core();
-
- /* If interrupts were disabled or CPU offline, don't invoke RCU core. */
- if (irqs_disabled_flags(flags) || cpu_is_offline(smp_processor_id()))
- return;
-
- /*
- * Force the grace period if too many callbacks or too long waiting.
- * Enforce hysteresis, and don't invoke rcu_force_quiescent_state()
- * if some other CPU has recently done so. Also, don't bother
- * invoking rcu_force_quiescent_state() if the newly enqueued callback
- * is the only one waiting for a grace period to complete.
- */
- if (unlikely(rcu_segcblist_n_cbs(&rdp->cblist) >
- rdp->qlen_last_fqs_check + qhimark)) {
-
- /* Are we ignoring a completed grace period? */
- note_gp_changes(rdp);
-
- /* Start a new grace period if one not already started. */
- if (!rcu_gp_in_progress()) {
- rcu_accelerate_cbs_unlocked(rdp->mynode, rdp);
- } else {
- /* Give the grace period a kick. */
- rdp->blimit = DEFAULT_MAX_RCU_BLIMIT;
- if (READ_ONCE(rcu_state.n_force_qs) == rdp->n_force_qs_snap &&
- rcu_segcblist_first_pend_cb(&rdp->cblist) != head)
- rcu_force_quiescent_state();
- rdp->n_force_qs_snap = READ_ONCE(rcu_state.n_force_qs);
- rdp->qlen_last_fqs_check = rcu_segcblist_n_cbs(&rdp->cblist);
- }
- }
}
/*
@@ -3121,7 +3090,7 @@ __call_rcu_common(struct rcu_head *head, rcu_callback_t func, bool lazy_in)
if (unlikely(rcu_rdp_is_offloaded(rdp)))
call_rcu_nocb(rdp, head, func, flags, lazy);
else
- call_rcu_core(rdp, head, func, flags);
+ call_rcu_core(rdp, head, func);
local_irq_restore(flags);
}
--
2.44.0
On 2024-04-29 13:34, Alan Huang wrote:
> call_rcu_core is only called from __call_rcu_common with interrupt
> disabled. This patch thus removes the unreachable logic and the would-be
> unused 'flags' parameter.
Nack.
call_rcu_core() receives a @flags parameter which are the _saved_ flags
as they were prior to local_irq_save().
This patch highlights a misunderstanding of what the code is actually
doing.
Thanks,
Mathieu
>
> Signed-off-by: Alan Huang <[email protected]>
> ---
> kernel/rcu/tree.c | 35 ++---------------------------------
> 1 file changed, 2 insertions(+), 33 deletions(-)
>
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index d5507ac1bbf1..b0ea2ebd7769 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -2983,7 +2983,7 @@ static void rcutree_enqueue(struct rcu_data *rdp, struct rcu_head *head, rcu_cal
> * Handle any core-RCU processing required by a call_rcu() invocation.
> */
> static void call_rcu_core(struct rcu_data *rdp, struct rcu_head *head,
> - rcu_callback_t func, unsigned long flags)
> + rcu_callback_t func)
> {
> rcutree_enqueue(rdp, head, func);
> /*
> @@ -2992,37 +2992,6 @@ static void call_rcu_core(struct rcu_data *rdp, struct rcu_head *head,
> */
> if (!rcu_is_watching())
> invoke_rcu_core();
> -
> - /* If interrupts were disabled or CPU offline, don't invoke RCU core. */
> - if (irqs_disabled_flags(flags) || cpu_is_offline(smp_processor_id()))
> - return;
> -
> - /*
> - * Force the grace period if too many callbacks or too long waiting.
> - * Enforce hysteresis, and don't invoke rcu_force_quiescent_state()
> - * if some other CPU has recently done so. Also, don't bother
> - * invoking rcu_force_quiescent_state() if the newly enqueued callback
> - * is the only one waiting for a grace period to complete.
> - */
> - if (unlikely(rcu_segcblist_n_cbs(&rdp->cblist) >
> - rdp->qlen_last_fqs_check + qhimark)) {
> -
> - /* Are we ignoring a completed grace period? */
> - note_gp_changes(rdp);
> -
> - /* Start a new grace period if one not already started. */
> - if (!rcu_gp_in_progress()) {
> - rcu_accelerate_cbs_unlocked(rdp->mynode, rdp);
> - } else {
> - /* Give the grace period a kick. */
> - rdp->blimit = DEFAULT_MAX_RCU_BLIMIT;
> - if (READ_ONCE(rcu_state.n_force_qs) == rdp->n_force_qs_snap &&
> - rcu_segcblist_first_pend_cb(&rdp->cblist) != head)
> - rcu_force_quiescent_state();
> - rdp->n_force_qs_snap = READ_ONCE(rcu_state.n_force_qs);
> - rdp->qlen_last_fqs_check = rcu_segcblist_n_cbs(&rdp->cblist);
> - }
> - }
> }
>
> /*
> @@ -3121,7 +3090,7 @@ __call_rcu_common(struct rcu_head *head, rcu_callback_t func, bool lazy_in)
> if (unlikely(rcu_rdp_is_offloaded(rdp)))
> call_rcu_nocb(rdp, head, func, flags, lazy);
> else
> - call_rcu_core(rdp, head, func, flags);
> + call_rcu_core(rdp, head, func);
> local_irq_restore(flags);
> }
>
--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com