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Subject[tip:core/locking] lockdep: Make held_lock->check and "int check" argument bool
Commit-ID:  fb9edbe98493fcd9df66de926ae9157cbe0e4dcd
Gitweb: http://git.kernel.org/tip/fb9edbe98493fcd9df66de926ae9157cbe0e4dcd
Author: Oleg Nesterov <oleg@redhat.com>
AuthorDate: Mon, 20 Jan 2014 19:20:06 +0100
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Sun, 9 Feb 2014 21:18:54 +0100

lockdep: Make held_lock->check and "int check" argument bool

The "int check" argument of lock_acquire() and held_lock->check are
misleading. This is actually a boolean: 2 means "true", everything
else is "false".

And there is no need to pass 1 or 0 to lock_acquire() depending on
CONFIG_PROVE_LOCKING, __lock_acquire() checks prove_locking at the
start and clears "check" if !CONFIG_PROVE_LOCKING.

Note: probably we can simply kill this member/arg. The only explicit
user of check => 0 is rcu_lock_acquire(), perhaps we can change it to
use lock_acquire(trylock =>, read => 2). __lockdep_no_validate means
check => 0 implicitly, but we can change validate_chain() to check
hlock->instance->key instead. Not to mention it would be nice to get
rid of lockdep_set_novalidate_class().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20140120182006.GA26495@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
drivers/tty/tty_ldsem.c | 15 ++++-----------
include/linux/lockdep.h | 25 +++++++++----------------
include/linux/rcupdate.h | 2 +-
kernel/locking/lockdep.c | 11 ++++-------
4 files changed, 18 insertions(+), 35 deletions(-)

diff --git a/drivers/tty/tty_ldsem.c b/drivers/tty/tty_ldsem.c
index d8a55e8..0ffb0cb 100644
--- a/drivers/tty/tty_ldsem.c
+++ b/drivers/tty/tty_ldsem.c
@@ -39,17 +39,10 @@
lock_acquire(&(l)->dep_map, s, t, r, c, n, i)
# define __rel(l, n, i) \
lock_release(&(l)->dep_map, n, i)
-# ifdef CONFIG_PROVE_LOCKING
-# define lockdep_acquire(l, s, t, i) __acq(l, s, t, 0, 2, NULL, i)
-# define lockdep_acquire_nest(l, s, t, n, i) __acq(l, s, t, 0, 2, n, i)
-# define lockdep_acquire_read(l, s, t, i) __acq(l, s, t, 1, 2, NULL, i)
-# define lockdep_release(l, n, i) __rel(l, n, i)
-# else
-# define lockdep_acquire(l, s, t, i) __acq(l, s, t, 0, 1, NULL, i)
-# define lockdep_acquire_nest(l, s, t, n, i) __acq(l, s, t, 0, 1, n, i)
-# define lockdep_acquire_read(l, s, t, i) __acq(l, s, t, 1, 1, NULL, i)
-# define lockdep_release(l, n, i) __rel(l, n, i)
-# endif
+#define lockdep_acquire(l, s, t, i) __acq(l, s, t, 0, 1, NULL, i)
+#define lockdep_acquire_nest(l, s, t, n, i) __acq(l, s, t, 0, 1, n, i)
+#define lockdep_acquire_read(l, s, t, i) __acq(l, s, t, 1, 1, NULL, i)
+#define lockdep_release(l, n, i) __rel(l, n, i)
#else
# define lockdep_acquire(l, s, t, i) do { } while (0)
# define lockdep_acquire_nest(l, s, t, n, i) do { } while (0)
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 92b1bfc..1626047 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -252,9 +252,9 @@ struct held_lock {
unsigned int trylock:1; /* 16 bits */

unsigned int read:2; /* see lock_acquire() comment */
- unsigned int check:2; /* see lock_acquire() comment */
+ unsigned int check:1; /* see lock_acquire() comment */
unsigned int hardirqs_off:1;
- unsigned int references:11; /* 32 bits */
+ unsigned int references:12; /* 32 bits */
};

/*
@@ -326,9 +326,8 @@ static inline int lockdep_match_key(struct lockdep_map *lock,
*
* Values for check:
*
- * 0: disabled
- * 1: simple checks (freeing, held-at-exit-time, etc.)
- * 2: full validation
+ * 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,
@@ -479,15 +478,9 @@ static inline void print_irqtrace_events(struct task_struct *curr)
* on the per lock-class debug mode:
*/

-#ifdef CONFIG_PROVE_LOCKING
- #define lock_acquire_exclusive(l, s, t, n, i) lock_acquire(l, s, t, 0, 2, n, i)
- #define lock_acquire_shared(l, s, t, n, i) lock_acquire(l, s, t, 1, 2, n, i)
- #define lock_acquire_shared_recursive(l, s, t, n, i) lock_acquire(l, s, t, 2, 2, n, i)
-#else
- #define lock_acquire_exclusive(l, s, t, n, i) lock_acquire(l, s, t, 0, 1, n, i)
- #define lock_acquire_shared(l, s, t, n, i) lock_acquire(l, s, t, 1, 1, n, i)
- #define lock_acquire_shared_recursive(l, s, t, n, i) lock_acquire(l, s, t, 2, 1, n, i)
-#endif
+#define lock_acquire_exclusive(l, s, t, n, i) lock_acquire(l, s, t, 0, 1, n, i)
+#define lock_acquire_shared(l, s, t, n, i) lock_acquire(l, s, t, 1, 1, n, i)
+#define lock_acquire_shared_recursive(l, s, t, n, i) lock_acquire(l, s, t, 2, 1, n, i)

#define spin_acquire(l, s, t, i) lock_acquire_exclusive(l, s, t, NULL, i)
#define spin_acquire_nest(l, s, t, n, i) lock_acquire_exclusive(l, s, t, n, i)
@@ -518,13 +511,13 @@ static inline void print_irqtrace_events(struct task_struct *curr)
# define might_lock(lock) \
do { \
typecheck(struct lockdep_map *, &(lock)->dep_map); \
- lock_acquire(&(lock)->dep_map, 0, 0, 0, 2, NULL, _THIS_IP_); \
+ lock_acquire(&(lock)->dep_map, 0, 0, 0, 1, NULL, _THIS_IP_); \
lock_release(&(lock)->dep_map, 0, _THIS_IP_); \
} while (0)
# define might_lock_read(lock) \
do { \
typecheck(struct lockdep_map *, &(lock)->dep_map); \
- lock_acquire(&(lock)->dep_map, 0, 0, 1, 2, NULL, _THIS_IP_); \
+ lock_acquire(&(lock)->dep_map, 0, 0, 1, 1, NULL, _THIS_IP_); \
lock_release(&(lock)->dep_map, 0, _THIS_IP_); \
} while (0)
#else
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 72bf3a0..adff3c9 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -314,7 +314,7 @@ static inline bool rcu_lockdep_current_cpu_online(void)

static inline void rcu_lock_acquire(struct lockdep_map *map)
{
- lock_acquire(map, 0, 0, 2, 1, NULL, _THIS_IP_);
+ lock_acquire(map, 0, 0, 2, 0, NULL, _THIS_IP_);
}

static inline void rcu_lock_release(struct lockdep_map *map)
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index eb8a547..8c85a0d 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -2098,7 +2098,7 @@ static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
* (If lookup_chain_cache() returns with 1 it acquires
* graph_lock for us)
*/
- if (!hlock->trylock && (hlock->check == 2) &&
+ if (!hlock->trylock && hlock->check &&
lookup_chain_cache(curr, hlock, chain_key)) {
/*
* Check whether last held lock:
@@ -3055,9 +3055,6 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
int class_idx;
u64 chain_key;

- if (!prove_locking)
- check = 1;
-
if (unlikely(!debug_locks))
return 0;

@@ -3069,8 +3066,8 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
return 0;

- if (lock->key == &__lockdep_no_validate__)
- check = 1;
+ if (!prove_locking || lock->key == &__lockdep_no_validate__)
+ check = 0;

if (subclass < NR_LOCKDEP_CACHING_CLASSES)
class = lock->class_cache[subclass];
@@ -3138,7 +3135,7 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
hlock->holdtime_stamp = lockstat_clock();
#endif

- if (check == 2 && !mark_irqflags(curr, hlock))
+ if (check && !mark_irqflags(curr, hlock))
return 0;

/* mark it as used: */

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