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Subject[PATCH v2 -rcu dev 5/5] rcu: Remove kfree_call_rcu_nobatch()
Date
Now that kfree_rcu() special casing have been removed from tree RCU,
remove kfree_call_rcu_nobatch() since it is not needed.

Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
---
.../admin-guide/kernel-parameters.txt | 4 ---
include/linux/rcutiny.h | 5 ---
include/linux/rcutree.h | 1 -
kernel/rcu/rcuperf.c | 10 +-----
kernel/rcu/tree.c | 34 ++++++++-----------
5 files changed, 15 insertions(+), 39 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 24fe8aefb12c..56be0e30100b 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3909,10 +3909,6 @@
Number of loops doing rcuperf.kfree_alloc_num number
of allocations and frees.

- rcuperf.kfree_no_batch= [KNL]
- Use the non-batching (less efficient) version of kfree_rcu().
- This is useful for comparing with the batched version.
-
rcuperf.nreaders= [KNL]
Set number of RCU readers. The value -1 selects
N, where N is the number of CPUs. A value
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index b7607e2667ae..37b6f0c2b79d 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -39,11 +39,6 @@ static inline void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
call_rcu(head, func);
}

-static inline void kfree_call_rcu_nobatch(struct rcu_head *head, rcu_callback_t func)
-{
- call_rcu(head, func);
-}
-
void rcu_qs(void);

static inline void rcu_softirq_qs(void)
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index 961b7e05d141..0b68aa952f8b 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -34,7 +34,6 @@ static inline void rcu_virt_note_context_switch(int cpu)

void synchronize_rcu_expedited(void);
void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func);
-void kfree_call_rcu_nobatch(struct rcu_head *head, rcu_callback_t func);

void rcu_barrier(void);
bool rcu_eqs_special_set(int cpu);
diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c
index c1e25fd10f2a..da94b89cd531 100644
--- a/kernel/rcu/rcuperf.c
+++ b/kernel/rcu/rcuperf.c
@@ -593,7 +593,6 @@ rcu_perf_shutdown(void *arg)
torture_param(int, kfree_nthreads, -1, "Number of threads running loops of kfree_rcu().");
torture_param(int, kfree_alloc_num, 8000, "Number of allocations and frees done in an iteration.");
torture_param(int, kfree_loops, 10, "Number of loops doing kfree_alloc_num allocations and frees.");
-torture_param(int, kfree_no_batch, 0, "Use the non-batching (slower) version of kfree_rcu().");

static struct task_struct **kfree_reader_tasks;
static int kfree_nrealthreads;
@@ -632,14 +631,7 @@ kfree_perf_thread(void *arg)
if (!alloc_ptr)
return -ENOMEM;

- if (!kfree_no_batch) {
- kfree_rcu(alloc_ptr, rh);
- } else {
- rcu_callback_t cb;
-
- cb = (rcu_callback_t)(unsigned long)offsetof(struct kfree_obj, rh);
- kfree_call_rcu_nobatch(&(alloc_ptr->rh), cb);
- }
+ kfree_rcu(alloc_ptr, rh);
}

cond_resched();
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index cd7bbc74ae20..72550343843f 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2770,8 +2770,10 @@ static void kfree_rcu_work(struct work_struct *work)
rcu_lock_acquire(&rcu_callback_map);
trace_rcu_invoke_kfree_callback(rcu_state.name, head, offset);

- /* Could be possible to optimize with kfree_bulk in future */
- kfree((void *)head - offset);
+ if (!WARN_ON_ONCE(!__is_kfree_rcu_offset(offset))) {
+ /* Could be optimized with kfree_bulk() in future. */
+ kfree((void *)head - offset);
+ }

rcu_lock_release(&rcu_callback_map);
cond_resched_tasks_rcu_qs();
@@ -2857,16 +2859,6 @@ static void kfree_rcu_monitor(struct work_struct *work)
}
}

-/*
- * This version of kfree_call_rcu does not do batching of kfree_rcu() requests.
- * Used only by rcuperf torture test for comparison with kfree_rcu_batch().
- */
-void kfree_call_rcu_nobatch(struct rcu_head *head, rcu_callback_t func)
-{
- __call_rcu(head, func);
-}
-EXPORT_SYMBOL_GPL(kfree_call_rcu_nobatch);
-
/*
* Queue a request for lazy invocation of kfree() after a grace period.
*
@@ -2886,12 +2878,6 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
unsigned long flags;
struct kfree_rcu_cpu *krcp;

- /* kfree_call_rcu() batching requires timers to be up. If the scheduler
- * is not yet up, just skip batching and do the non-batched version.
- */
- if (rcu_scheduler_active != RCU_SCHEDULER_RUNNING)
- return kfree_call_rcu_nobatch(head, func);
-
if (debug_rcu_head_queue(head)) {
/* Probable double kfree_rcu() */
WARN_ONCE(1, "kfree_call_rcu(): Double-freed call. rcu_head %p\n",
@@ -2910,8 +2896,16 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
krcp->head = head;

/* Schedule monitor for timely drain after KFREE_DRAIN_JIFFIES. */
- if (!xchg(&krcp->monitor_todo, true))
- schedule_delayed_work(&krcp->monitor_work, KFREE_DRAIN_JIFFIES);
+ if (!krcp->monitor_todo) {
+ krcp->monitor_todo = true;
+ /* Scheduling the monitor requires scheduler/timers to be up,
+ * if it is not, just skip it. An eventual kfree_rcu() will
+ * kick it again.
+ */
+ if (rcu_scheduler_active == RCU_SCHEDULER_RUNNING) {
+ schedule_delayed_work(&krcp->monitor_work, KFREE_DRAIN_JIFFIES);
+ }
+ }

spin_unlock(&krcp->lock);
local_irq_restore(flags);
--
2.23.0.187.g17f5b7556c-goog
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