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Date: Wed, 22 May 2013 11:22:32 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Sasha Levin <sasha.levin@...cle.com>
Cc: torvalds@...ux-foundation.org, mingo@...nel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 3/9] liblockdep: Add public headers for
pthread_mutex_t implementation
On Wed, May 15, 2013 at 11:15:35PM -0400, Sasha Levin wrote:
> These headers provide the same API as their pthread mutex
> counterparts.
>
> The design here is to allow to easily switch to liblockdep lock
> validation just by adding a "liblockdep_" to pthread_mutex_*()
> calls, which means that it's easy to integrate liblockdep into
> existing codebases.
>
> Signed-off-by: Sasha Levin <sasha.levin@...cle.com>
> ---
> tools/lib/lockdep/include/liblockdep/common.h | 42 ++++++++++++++++
> tools/lib/lockdep/include/liblockdep/mutex.h | 70 +++++++++++++++++++++++++++
> 2 files changed, 112 insertions(+)
> create mode 100644 tools/lib/lockdep/include/liblockdep/common.h
> create mode 100644 tools/lib/lockdep/include/liblockdep/mutex.h
>
> diff --git a/tools/lib/lockdep/include/liblockdep/common.h b/tools/lib/lockdep/include/liblockdep/common.h
> new file mode 100644
> index 0000000..1113cad
> --- /dev/null
> +++ b/tools/lib/lockdep/include/liblockdep/common.h
> @@ -0,0 +1,42 @@
> +#ifndef _LIBLOCKDEP_COMMON_H
> +#define _LIBLOCKDEP_COMMON_H
> +
> +#include <pthread.h>
> +
> +#ifndef _THIS_IP_
#ifndef _RET_IP_ ?
> +#define _RET_IP_ (unsigned long)__builtin_return_address(0)
> +#endif
> +
> +#define NR_LOCKDEP_CACHING_CLASSES 2
> +#define MAX_LOCKDEP_SUBCLASSES 8UL
> +
> +struct lockdep_subclass_key {
> + char __one_byte;
> +};
> +
> +struct lock_class_key {
> + struct lockdep_subclass_key subkeys[MAX_LOCKDEP_SUBCLASSES];
> +};
> +
> +struct lockdep_map {
> + struct lock_class_key *key;
> + struct lock_class *class_cache[NR_LOCKDEP_CACHING_CLASSES];
> + const char *name;
> +#ifdef CONFIG_LOCK_STAT
> + int cpu;
> + unsigned long ip;
> +#endif
> +};
> +
> +void lockdep_init_map(struct lockdep_map *lock, const char *name,
> + struct lock_class_key *key, int subclass);
> +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 lock_release(struct lockdep_map *lock, int nested,
> + unsigned long ip);
> +
> +#define STATIC_LOCKDEP_MAP_INIT(_name, _key) \
> + { .name = (_name), .key = (void *)(_key), }
> +
> +#endif
> diff --git a/tools/lib/lockdep/include/liblockdep/mutex.h b/tools/lib/lockdep/include/liblockdep/mutex.h
> new file mode 100644
> index 0000000..c342f70
> --- /dev/null
> +++ b/tools/lib/lockdep/include/liblockdep/mutex.h
> @@ -0,0 +1,70 @@
> +#ifndef _LIBLOCKDEP_MUTEX_H
> +#define _LIBLOCKDEP_MUTEX_H
> +
> +#include <pthread.h>
> +#include "common.h"
> +
> +struct liblockdep_pthread_mutex {
> + pthread_mutex_t mutex;
> + struct lockdep_map dep_map;
> +};
> +
> +typedef struct liblockdep_pthread_mutex liblockdep_pthread_mutex_t;
> +
> +#define LIBLOCKDEP_PTHREAD_MUTEX_INITIALIZER(mtx) \
> + (const struct liblockdep_pthread_mutex) { \
> + .mutex = PTHREAD_MUTEX_INITIALIZER, \
> + .dep_map = STATIC_LOCKDEP_MAP_INIT(#mtx, &((&(mtx))->dep_map)), \
> +}
> +
> +static inline int __mutex_init(liblockdep_pthread_mutex_t *lock,
> + const char *name,
> + struct lock_class_key *key,
> + const pthread_mutexattr_t *__mutexattr)
> +{
> + lockdep_init_map(&lock->dep_map, name, key, 0);
> + return pthread_mutex_init(&lock->mutex, __mutexattr);
> +}
> +
> +#define liblockdep_pthread_mutex_init(mutex, mutexattr) \
> +({ \
> + static struct lock_class_key __key; \
> + \
> + __mutex_init((mutex), #mutex, &__key, (mutexattr)); \
> +})
OK, so people using liblockdep_pthread_mutex_init() do get the 'normal'
class rules.
> +
> +static inline int liblockdep_pthread_mutex_lock(liblockdep_pthread_mutex_t *lock)
> +{
> + lock_acquire(&lock->dep_map, 0, 0, 0, 2, NULL, (unsigned long)_RET_IP_);
> + return pthread_mutex_lock(&lock->mutex);
> +}
They will however then also want all the 'normal' lockdep annotations to
deal with that like:
liblockdep_pthread_mutex_lock_nested()
liblockdep_pthread_mutex_lock_nest_lock()
*phew* and here I always though pthread_mutex_* was a long prefix...
Also, the above doesn't have the full lockstat contention hooks -- not
sure that's on purpose or not.
> +
> +static inline int liblockdep_pthread_mutex_unlock(liblockdep_pthread_mutex_t *lock)
> +{
> + lock_release(&lock->dep_map, 0, (unsigned long)_RET_IP_);
> + return pthread_mutex_unlock(&lock->mutex);
> +}
> +
> +static inline int liblockdep_pthread_mutex_trylock(liblockdep_pthread_mutex_t *lock)
> +{
> + lock_acquire(&lock->dep_map, 0, 1, 0, 2, NULL, (unsigned long)_RET_IP_);
> + return pthread_mutex_trylock(&lock->mutex) == 0 ? 1 : 0;
> +}
> +
> +static inline int liblockdep_pthread_mutex_destroy(liblockdep_pthread_mutex_t *lock)
> +{
> + return pthread_mutex_destroy(&lock->mutex);
> +}
> +
> +#ifdef __USE_LIBLOCKDEP
> +
> +#define pthread_mutex_t liblockdep_pthread_mutex_t
> +#define pthread_mutex_init liblockdep_pthread_mutex_init
> +#define pthread_mutex_lock liblockdep_pthread_mutex_lock
> +#define pthread_mutex_unlock liblockdep_pthread_mutex_unlock
> +#define pthread_mutex_trylock liblockdep_pthread_mutex_trylock
> +#define pthread_mutex_destroy liblockdep_pthread_mutex_destroy
Given the liblockdep_* things use 'proper' classes do you want this
mapping? If you do, should we use the same alias nonsense glibc uses or
are CPP macros good enough for us?
--
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