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/* dyninst probe locking header file
* Copyright (C) 2012 Red Hat Inc.
*
* This file is part of systemtap, and is free software. You can
* redistribute it and/or modify it under the terms of the GNU General
* Public License (GPL); either version 2, or (at your option) any
* later version.
*/
#ifndef _STAPDYN_PROBE_LOCK_H
#define _STAPDYN_PROBE_LOCK_H
#include <pthread.h>
struct stp_probe_lock {
#ifdef STP_TIMING
atomic_t *skipped;
#endif
pthread_rwlock_t *lock;
unsigned write_p;
};
static void
stp_unlock_probe(const struct stp_probe_lock *locks, unsigned num_locks)
{
unsigned i;
for (i = num_locks; i-- > 0;) {
pthread_rwlock_unlock(locks[i].lock);
}
}
static unsigned
stp_lock_probe(const struct stp_probe_lock *locks, unsigned num_locks)
{
#if 0 // XXX: should we bother with trylocks in pure userspace?
unsigned i, retries = 0;
for (i = 0; i < num_locks; ++i) {
if (locks[i].write_p)
while (!pthread_rwlock_trywrlock(locks[i].lock)) {
#if !define(STAP_SUPRESS_TIME_LIMITS_ENABLE)
if (++retries > MAXTRYLOCK)
goto skip;
#endif
udelay (TRYLOCKDELAY);
}
else
while (!pthread_rwlock_tryrdlock(locks[i].lock)) {
#if !define(STAP_SUPPRESS_TIME_LIMITS_ENABLE)
if (++retries > MAXTRYLOCK)
goto skip;
#endif
udelay (TRYLOCKDELAY);
}
}
return 1;
skip:
atomic_inc(skipped_count());
#ifdef STP_TIMING
atomic_inc(locks[i].skipped);
#endif
stp_unlock_probe(locks, i);
return 0;
#else
unsigned i;
for (i = 0; i < num_locks; ++i) {
if (locks[i].write_p)
pthread_rwlock_wrlock(locks[i].lock);
else
pthread_rwlock_rdlock(locks[i].lock);
}
return 1;
#endif
}
#endif /* _STAPDYN_PROBE_LOCK_H */
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