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

[Sasha Levin]

On 05/22/2013 05:27 AM, Peter Zijlstra wrote:
> 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?

I assumed we didn't want to give up on that based on your patch. I think that
if we plan to get it into tools/lib/ we shouldn't give up on that straight away.


Thanks,
Sasha

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