[PATCH tip/core/rcu 7/7] rcu: Remove kfree_call_rcu_nobatch()

From: paulmck@kernel.org
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com,
	mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com,
	akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
	josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
	rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
	fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org,
	"Paul E . McKenney" <paulmck@kernel.org>
Subject: [PATCH tip/core/rcu 7/7] rcu: Remove kfree_call_rcu_nobatch()
Date: Mon,  9 Dec 2019 20:11:47 -0800	[thread overview]
Message-ID: <20191210041147.3181-7-paulmck@kernel.org> (raw)
In-Reply-To: <20191210041118.GA3115@paulmck-ThinkPad-P72>

From: "Joel Fernandes (Google)" <joel@joelfernandes.org>

Now that the kfree_rcu() special-casing has been removed from tree RCU,
this commit removes kfree_call_rcu_nobatch() since it is no longer needed.

Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 Documentation/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                               | 18 ++++--------------
 5 files changed, 5 insertions(+), 33 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 3ce270b..ed83d6d 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3991,10 +3991,6 @@
 			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 1bd166a..b2b2dc9 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 6a65d3a..2f787b9 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 c1e25fd..da94b89 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 a8dd612..31d2d92 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2763,8 +2763,10 @@ 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();
@@ -2836,16 +2838,6 @@ 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.
  *
  * Each kfree_call_rcu() request is added to a batch. The batch will be drained
@@ -2864,8 +2856,6 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
 	unsigned long flags;
 	struct kfree_rcu_cpu *krcp;
 
-	head->func = func;
-
 	local_irq_save(flags);	// For safely calling this_cpu_ptr().
 	krcp = this_cpu_ptr(&krc);
 	if (krcp->initialized)
-- 
2.9.5

