[PATCH 0/2] Replace explicit function pointer types with rcu_callback_t and call_rcu_func_t

[PATCH 0/2] Replace explicit function pointer types with rcu_callback_t and call_rcu_func_t

[Boqun Feng]

Commit ("rcu: Create a synchronize_rcu_mult()") in linux-rcu.git#rcu/next
branch has introduced rcu_callback_t as the type for rcu callback
functions and call_rcu_func_t has been introduced for a while. This patch
series uses the rcu_callback_t and call_rcu_func_t to save a few lines of
code.

This patchset is based on rcu/next branch of Paul's linux-rcu tree, and
consists of two patches:

1.	Use rcu_callback_t as the type of callbacks in call_rcu*() and
	friends

2.	Use call_rcu_func_t to replace the equivalent but complicated
	function pointer type.

Besides cleaning up the code, this patchset can also help code tag program,
such as cscope to generate a better database.

This patchset has been already tested by 0day.

Regards,
Boqun

-------------------------------------------------------------------------
 include/linux/rcupdate.h | 10 +++++-----
 include/linux/rcutiny.h  |  2 +-
 include/linux/rcutree.h  |  2 +-
 kernel/rcu/rcutorture.c  |  6 +++---
 kernel/rcu/srcu.c        |  2 +-
 kernel/rcu/tiny.c        |  8 ++++----
 kernel/rcu/tree.c        |  8 ++++----
 kernel/rcu/tree.h        |  5 ++---
 kernel/rcu/tree_plugin.h |  2 +-
 kernel/rcu/update.c      |  2 +-
 10 files changed, 23 insertions(+), 24 deletions(-)

-- 
2.4.6

[PATCH 1/2] rcu: Use rcu_callback_t in call_rcu*() and friends

[Boqun Feng]

As we now have rcu_callback_t typedefs as the type of rcu callbacks, we
should use it in call_rcu*() and friends as the type of parameters. This
could save us a few lines of code and make it clear which function
requires an rcu callbacks rather than other callbacks as its argument.

Besides, this can also help cscope to generate a better database for
code reading.

Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
---
 include/linux/rcupdate.h | 10 +++++-----
 include/linux/rcutiny.h  |  2 +-
 include/linux/rcutree.h  |  2 +-
 kernel/rcu/rcutorture.c  |  4 ++--
 kernel/rcu/srcu.c        |  2 +-
 kernel/rcu/tiny.c        |  8 ++++----
 kernel/rcu/tree.c        |  8 ++++----
 kernel/rcu/tree.h        |  2 +-
 kernel/rcu/tree_plugin.h |  2 +-
 kernel/rcu/update.c      |  2 +-
 10 files changed, 21 insertions(+), 21 deletions(-)

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index ff47651..78af46c 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -160,7 +160,7 @@ void do_trace_rcu_torture_read(const char *rcutorturename,
  * more than one CPU).
  */
 void call_rcu(struct rcu_head *head,
-	      void (*func)(struct rcu_head *head));
+	      rcu_callback_t func);
 
 #else /* #ifdef CONFIG_PREEMPT_RCU */
 
@@ -191,7 +191,7 @@ void call_rcu(struct rcu_head *head,
  * memory ordering guarantees.
  */
 void call_rcu_bh(struct rcu_head *head,
-		 void (*func)(struct rcu_head *head));
+		 rcu_callback_t func);
 
 /**
  * call_rcu_sched() - Queue an RCU for invocation after sched grace period.
@@ -213,7 +213,7 @@ void call_rcu_bh(struct rcu_head *head,
  * memory ordering guarantees.
  */
 void call_rcu_sched(struct rcu_head *head,
-		    void (*func)(struct rcu_head *rcu));
+		    rcu_callback_t func);
 
 void synchronize_sched(void);
 
@@ -275,7 +275,7 @@ do { \
  * See the description of call_rcu() for more detailed information on
  * memory ordering guarantees.
  */
-void call_rcu_tasks(struct rcu_head *head, void (*func)(struct rcu_head *head));
+void call_rcu_tasks(struct rcu_head *head, rcu_callback_t func);
 void synchronize_rcu_tasks(void);
 void rcu_barrier_tasks(void);
 
@@ -1066,7 +1066,7 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
 #define __kfree_rcu(head, offset) \
 	do { \
 		BUILD_BUG_ON(!__is_kfree_rcu_offset(offset)); \
-		kfree_call_rcu(head, (void (*)(struct rcu_head *))(unsigned long)(offset)); \
+		kfree_call_rcu(head, (rcu_callback_t)(unsigned long)(offset)); \
 	} while (0)
 
 /**
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index ff968b7..c8a0722 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -83,7 +83,7 @@ static inline void synchronize_sched_expedited(void)
 }
 
 static inline void kfree_call_rcu(struct rcu_head *head,
-				  void (*func)(struct rcu_head *rcu))
+				  rcu_callback_t func)
 {
 	call_rcu(head, func);
 }
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index 5abec82..60d15a0 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -48,7 +48,7 @@ void synchronize_rcu_bh(void);
 void synchronize_sched_expedited(void);
 void synchronize_rcu_expedited(void);
 
-void kfree_call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
+void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func);
 
 /**
  * synchronize_rcu_bh_expedited - Brute-force RCU-bh grace period
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 7719295..51c8e7f 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -448,7 +448,7 @@ static void synchronize_rcu_busted(void)
 }
 
 static void
-call_rcu_busted(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
+call_rcu_busted(struct rcu_head *head, rcu_callback_t func)
 {
 	/* This is a deliberate bug for testing purposes only! */
 	func(head);
@@ -523,7 +523,7 @@ static void srcu_torture_synchronize(void)
 }
 
 static void srcu_torture_call(struct rcu_head *head,
-			      void (*func)(struct rcu_head *head))
+			      rcu_callback_t func)
 {
 	call_srcu(srcu_ctlp, head, func);
 }
diff --git a/kernel/rcu/srcu.c b/kernel/rcu/srcu.c
index d3fcb2e..9e61225 100644
--- a/kernel/rcu/srcu.c
+++ b/kernel/rcu/srcu.c
@@ -387,7 +387,7 @@ static void srcu_flip(struct srcu_struct *sp)
  * srcu_struct structure.
  */
 void call_srcu(struct srcu_struct *sp, struct rcu_head *head,
-		void (*func)(struct rcu_head *head))
+	       rcu_callback_t func)
 {
 	unsigned long flags;
 
diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c
index d047105..944b1b4 100644
--- a/kernel/rcu/tiny.c
+++ b/kernel/rcu/tiny.c
@@ -44,7 +44,7 @@ struct rcu_ctrlblk;
 static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp);
 static void rcu_process_callbacks(struct softirq_action *unused);
 static void __call_rcu(struct rcu_head *head,
-		       void (*func)(struct rcu_head *rcu),
+		       rcu_callback_t func,
 		       struct rcu_ctrlblk *rcp);
 
 #include "tiny_plugin.h"
@@ -203,7 +203,7 @@ EXPORT_SYMBOL_GPL(synchronize_sched);
  * Helper function for call_rcu() and call_rcu_bh().
  */
 static void __call_rcu(struct rcu_head *head,
-		       void (*func)(struct rcu_head *rcu),
+		       rcu_callback_t func,
 		       struct rcu_ctrlblk *rcp)
 {
 	unsigned long flags;
@@ -229,7 +229,7 @@ static void __call_rcu(struct rcu_head *head,
  * period.  But since we have but one CPU, that would be after any
  * quiescent state.
  */
-void call_rcu_sched(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
+void call_rcu_sched(struct rcu_head *head, rcu_callback_t func)
 {
 	__call_rcu(head, func, &rcu_sched_ctrlblk);
 }
@@ -239,7 +239,7 @@ EXPORT_SYMBOL_GPL(call_rcu_sched);
  * Post an RCU bottom-half callback to be invoked after any subsequent
  * quiescent state.
  */
-void call_rcu_bh(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
+void call_rcu_bh(struct rcu_head *head, rcu_callback_t func)
 {
 	__call_rcu(head, func, &rcu_bh_ctrlblk);
 }
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 9f75f25..34a4308 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3017,7 +3017,7 @@ static void rcu_leak_callback(struct rcu_head *rhp)
  * is expected to specify a CPU.
  */
 static void
-__call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
+__call_rcu(struct rcu_head *head, rcu_callback_t func,
 	   struct rcu_state *rsp, int cpu, bool lazy)
 {
 	unsigned long flags;
@@ -3088,7 +3088,7 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
 /*
  * Queue an RCU-sched callback for invocation after a grace period.
  */
-void call_rcu_sched(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
+void call_rcu_sched(struct rcu_head *head, rcu_callback_t func)
 {
 	__call_rcu(head, func, &rcu_sched_state, -1, 0);
 }
@@ -3097,7 +3097,7 @@ EXPORT_SYMBOL_GPL(call_rcu_sched);
 /*
  * Queue an RCU callback for invocation after a quicker grace period.
  */
-void call_rcu_bh(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
+void call_rcu_bh(struct rcu_head *head, rcu_callback_t func)
 {
 	__call_rcu(head, func, &rcu_bh_state, -1, 0);
 }
@@ -3111,7 +3111,7 @@ EXPORT_SYMBOL_GPL(call_rcu_bh);
  * function may only be called from __kfree_rcu().
  */
 void kfree_call_rcu(struct rcu_head *head,
-		    void (*func)(struct rcu_head *rcu))
+		    rcu_callback_t func)
 {
 	__call_rcu(head, func, rcu_state_p, -1, 1);
 }
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 2e991f8..ad11529 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -584,7 +584,7 @@ static void rcu_print_detail_task_stall(struct rcu_state *rsp);
 static int rcu_print_task_stall(struct rcu_node *rnp);
 static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp);
 static void rcu_preempt_check_callbacks(void);
-void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
+void call_rcu(struct rcu_head *head, rcu_callback_t func);
 static void __init __rcu_init_preempt(void);
 static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags);
 static void rcu_preempt_boost_start_gp(struct rcu_node *rnp);
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index b2bf396..06116ae 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -500,7 +500,7 @@ static void rcu_preempt_do_callbacks(void)
 /*
  * Queue a preemptible-RCU callback for invocation after a grace period.
  */
-void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
+void call_rcu(struct rcu_head *head, rcu_callback_t func)
 {
 	__call_rcu(head, func, rcu_state_p, -1, 0);
 }
diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 7a0b3bc..5f748c5 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -534,7 +534,7 @@ static void rcu_spawn_tasks_kthread(void);
  * Post an RCU-tasks callback.  First call must be from process context
  * after the scheduler if fully operational.
  */
-void call_rcu_tasks(struct rcu_head *rhp, void (*func)(struct rcu_head *rhp))
+void call_rcu_tasks(struct rcu_head *rhp, rcu_callback_t func)
 {
 	unsigned long flags;
 	bool needwake;
-- 
2.4.6

[PATCH 2/2] rcu: Use call_rcu_func_to to replace explicit type equivalents

[Boqun Feng]

We have call_rcu_func_t for a quite while, but we still use explicit
function pointer type equivalents in some places, this patch replace
these equivalent types with call_rcu_func_t to gain better readability.

Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
---
 kernel/rcu/rcutorture.c | 2 +-
 kernel/rcu/tree.h       | 3 +--
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 51c8e7f..f9ec6cb 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -252,7 +252,7 @@ struct rcu_torture_ops {
 	void (*exp_sync)(void);
 	unsigned long (*get_state)(void);
 	void (*cond_sync)(unsigned long oldstate);
-	void (*call)(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
+	call_rcu_func_t call;
 	void (*cb_barrier)(void);
 	void (*fqs)(void);
 	void (*stats)(void);
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index ad11529..0c33c82 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -464,8 +464,7 @@ struct rcu_state {
 						/*  shut bogus gcc warning) */
 	u8 flavor_mask;				/* bit in flavor mask. */
 	struct rcu_data __percpu *rda;		/* pointer of percu rcu_data. */
-	void (*call)(struct rcu_head *head,	/* call_rcu() flavor. */
-		     void (*func)(struct rcu_head *head));
+	call_rcu_func_t call;			/* call_rcu() flavor. */
 
 	/* The following fields are guarded by the root rcu_node's lock. */
 
-- 
2.4.6

Re: [PATCH 0/2] Replace explicit function pointer types with rcu_callback_t and call_rcu_func_t

[Paul E. McKenney]

On Wed, Jul 29, 2015 at 01:29:37PM +0800, Boqun Feng wrote:
> Commit ("rcu: Create a synchronize_rcu_mult()") in linux-rcu.git#rcu/next
> branch has introduced rcu_callback_t as the type for rcu callback
> functions and call_rcu_func_t has been introduced for a while. This patch
> series uses the rcu_callback_t and call_rcu_func_t to save a few lines of
> code.
> 
> This patchset is based on rcu/next branch of Paul's linux-rcu tree, and
> consists of two patches:
> 
> 1.	Use rcu_callback_t as the type of callbacks in call_rcu*() and
> 	friends
> 
> 2.	Use call_rcu_func_t to replace the equivalent but complicated
> 	function pointer type.
> 
> Besides cleaning up the code, this patchset can also help code tag program,
> such as cscope to generate a better database.
> 
> This patchset has been already tested by 0day.

Hello, Boqun,

I have queued these for local testing.

							Thanx, Paul

> Regards,
> Boqun
> 
> -------------------------------------------------------------------------
>  include/linux/rcupdate.h | 10 +++++-----
>  include/linux/rcutiny.h  |  2 +-
>  include/linux/rcutree.h  |  2 +-
>  kernel/rcu/rcutorture.c  |  6 +++---
>  kernel/rcu/srcu.c        |  2 +-
>  kernel/rcu/tiny.c        |  8 ++++----
>  kernel/rcu/tree.c        |  8 ++++----
>  kernel/rcu/tree.h        |  5 ++---
>  kernel/rcu/tree_plugin.h |  2 +-
>  kernel/rcu/update.c      |  2 +-
>  10 files changed, 23 insertions(+), 24 deletions(-)
> 
> -- 
> 2.4.6
>