Re: [PATCH v4 7/9] liblockdep: Support using LD_PRELOAD

[Peter Zijlstra]

On Wed, May 15, 2013 at 11:15:39PM -0400, Sasha Levin wrote:
> +
> +/* pthread mutex API */
> +
> +#ifdef __GLIBC__
> +extern int __pthread_mutex_init(pthread_mutex_t *mutex, const pthread_mutexattr_t *attr);
> +extern int __pthread_mutex_lock(pthread_mutex_t *mutex);
> +extern int __pthread_mutex_trylock(pthread_mutex_t *mutex);
> +extern int __pthread_mutex_unlock(pthread_mutex_t *mutex);
> +extern int __pthread_mutex_destroy(pthread_mutex_t *mutex);
> +#else
> +#define __pthread_mutex_init	NULL
> +#define __pthread_mutex_lock	NULL
> +#define __pthread_mutex_trylock	NULL
> +#define __pthread_mutex_unlock	NULL
> +#define __pthread_mutex_destroy	NULL
> +#endif
> +static int (*ll_pthread_mutex_init)(pthread_mutex_t *mutex,
> +			const pthread_mutexattr_t *attr)	= __pthread_mutex_init;
> +static int (*ll_pthread_mutex_lock)(pthread_mutex_t *mutex)	= __pthread_mutex_lock;
> +static int (*ll_pthread_mutex_trylock)(pthread_mutex_t *mutex)	= __pthread_mutex_trylock;
> +static int (*ll_pthread_mutex_unlock)(pthread_mutex_t *mutex)	= __pthread_mutex_unlock;
> +static int (*ll_pthread_mutex_destroy)(pthread_mutex_t *mutex)	= __pthread_mutex_destroy;
> +
> +/* pthread rwlock API */
> +
> +#ifdef __GLIBC__
> +extern int __pthread_rwlock_init(pthread_rwlock_t *rwlock, const pthread_rwlockattr_t *attr);
> +extern int __pthread_rwlock_destroy(pthread_rwlock_t *rwlock);
> +extern int __pthread_rwlock_wrlock(pthread_rwlock_t *rwlock);
> +extern int __pthread_rwlock_trywrlock(pthread_rwlock_t *rwlock);
> +extern int __pthread_rwlock_rdlock(pthread_rwlock_t *rwlock);
> +extern int __pthread_rwlock_tryrdlock(pthread_rwlock_t *rwlock);
> +extern int __pthread_rwlock_unlock(pthread_rwlock_t *rwlock);
> +#else
> +#define __pthread_rwlock_init		NULL
> +#define __pthread_rwlock_destroy	NULL
> +#define __pthread_rwlock_wrlock		NULL
> +#define __pthread_rwlock_trywrlock	NULL
> +#define __pthread_rwlock_rdlock		NULL
> +#define __pthread_rwlock_tryrdlock	NULL
> +#define __pthread_rwlock_unlock		NULL
> +#endif
> +
> +static int (*ll_pthread_rwlock_init)(pthread_rwlock_t *rwlock,
> +			const pthread_rwlockattr_t *attr)		= __pthread_rwlock_init;
> +static int (*ll_pthread_rwlock_destroy)(pthread_rwlock_t *rwlock)	= __pthread_rwlock_destroy;
> +static int (*ll_pthread_rwlock_rdlock)(pthread_rwlock_t *rwlock)	= __pthread_rwlock_rdlock;
> +static int (*ll_pthread_rwlock_tryrdlock)(pthread_rwlock_t *rwlock)	= __pthread_rwlock_tryrdlock;
> +static int (*ll_pthread_rwlock_trywrlock)(pthread_rwlock_t *rwlock)	= __pthread_rwlock_trywrlock;
> +static int (*ll_pthread_rwlock_wrlock)(pthread_rwlock_t *rwlock)	= __pthread_rwlock_wrlock;
> +static int (*ll_pthread_rwlock_unlock)(pthread_rwlock_t *rwlock)	= __pthread_rwlock_unlock;
> +

> +__attribute__((constructor)) static void init_preload(void)
> +{
> +	if (__init_state != done)
> +		return;
> +
> +#ifndef __GLIBC__
> +	__init_state = prepare;
> +
> +	ll_pthread_mutex_init = dlsym(RTLD_NEXT, "pthread_mutex_init");
> +	ll_pthread_mutex_lock = dlsym(RTLD_NEXT, "pthread_mutex_lock");
> +	ll_pthread_mutex_trylock = dlsym(RTLD_NEXT, "pthread_mutex_trylock");
> +	ll_pthread_mutex_unlock = dlsym(RTLD_NEXT, "pthread_mutex_unlock");
> +	ll_pthread_mutex_destroy = dlsym(RTLD_NEXT, "pthread_mutex_destroy");
> +
> +	ll_pthread_rwlock_init = dlsym(RTLD_NEXT, "pthread_rwlock_init");
> +	ll_pthread_rwlock_destroy = dlsym(RTLD_NEXT, "pthread_rwlock_destroy");
> +	ll_pthread_rwlock_rdlock = dlsym(RTLD_NEXT, "pthread_rwlock_rdlock");
> +	ll_pthread_rwlock_tryrdlock = dlsym(RTLD_NEXT, "pthread_rwlock_tryrdlock");
> +	ll_pthread_rwlock_wrlock = dlsym(RTLD_NEXT, "pthread_rwlock_wrlock");
> +	ll_pthread_rwlock_trywrlock = dlsym(RTLD_NEXT, "pthread_rwlock_trywrlock");
> +	ll_pthread_rwlock_unlock = dlsym(RTLD_NEXT, "pthread_rwlock_unlock");
> +#endif
> +
> +	printf("%p\n", ll_pthread_mutex_trylock);fflush(stdout);
> +
> +	lockdep_init();
> +
> +	__init_state = done;
> +}

I guess that begs the question do we really want to support !glibc?
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