linux-kernel - Re: [PATCH 5/5] lockdep: pack subclass/trylock/read/check into a single argument

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Message-ID: <20140121141022.GX31570@twins.programming.kicks-ass.net>
Date:	Tue, 21 Jan 2014 15:10:22 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Alan Stern <stern@...land.harvard.edu>,
	Dave Jones <davej@...hat.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Ingo Molnar <mingo@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Paul McKenney <paulmck@...ux.vnet.ibm.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/5] lockdep: pack subclass/trylock/read/check into a
 single argument


I tried the below but filed to see my vmlinux shrink, maybe I'm just not
building the right kernel, or otherwise GCC is stupid.

---
 include/linux/lockdep.h  |   33 ++++++++++++++++++++++++++++++---
 kernel/locking/lockdep.c |   11 +++++++----
 2 files changed, 32 insertions(+), 7 deletions(-)

--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -329,9 +329,31 @@ static inline int lockdep_match_key(stru
  *   0: simple checks (freeing, held-at-exit-time, etc.)
  *   1: full validation
  */
-extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
-			 int trylock, int read, int check,
-			 struct lockdep_map *nest_lock, unsigned long ip);
+struct lockdep_acquire_flags {
+	unsigned long subclass : 3;
+	unsigned long trylock  : 1;
+	unsigned long read     : 2;
+	unsigned long check    : 1;
+};
+
+extern void do_lock_acquire(struct lockdep_map *lock,
+			    struct lockdep_acquire_flags acqf,
+			    struct lockdep_map *nest_lock,
+			    unsigned long ip);
+
+static inline void lock_acquire(struct lockdep_map *lock,
+		unsigned int subclass, int trylock, int read, int check,
+		struct lockdep_map *nest_lock, unsigned long ip)
+{
+	struct lockdep_acquire_flags acqf = {
+		.subclass = subclass,
+		.trylock = trylock,
+		.read = read,
+		.check = check,
+	};
+
+	do_lock_acquire(lock, acqf, nest_lock, ip);
+}
 
 extern void lock_release(struct lockdep_map *lock, int nested,
 			 unsigned long ip);
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3583,10 +3583,13 @@ EXPORT_SYMBOL_GPL(lock_set_class);
  * We are not always called with irqs disabled - do that here,
  * and also avoid lockdep recursion:
  */
-void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
-			  int trylock, int read, int check,
-			  struct lockdep_map *nest_lock, unsigned long ip)
+void do_lock_acquire(struct lockdep_map *lock, struct lockdep_acquire_flags acqf,
+			struct lockdep_map *nest_lock, unsigned long ip)
 {
+	unsigned int subclass = acqf.subclass;
+	unsigned int trylock = acqf.trylock;
+	unsigned int read = acqf.read;
+	unsigned int check = acqf.check;
 	unsigned long flags;
 
 	if (unlikely(current->lockdep_recursion))
@@ -3602,7 +3605,7 @@ void lock_acquire(struct lockdep_map *lo
 	current->lockdep_recursion = 0;
 	raw_local_irq_restore(flags);
 }
-EXPORT_SYMBOL_GPL(lock_acquire);
+EXPORT_SYMBOL_GPL(do_lock_acquire);
 
 void lock_release(struct lockdep_map *lock, int nested,
 			  unsigned long ip)
--
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