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/* nbdkit
* Copyright Red Hat
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* * Neither the name of Red Hat nor the names of its contributors may be
* used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include "internal.h"
/* Note that the plugin's thread model cannot change after being
* loaded, so caching it here is safe.
*/
unsigned thread_model = -1;
static pthread_mutex_t connection_lock = PTHREAD_MUTEX_INITIALIZER;
static pthread_mutex_t all_requests_lock = PTHREAD_MUTEX_INITIALIZER;
static pthread_rwlock_t unload_prevention_lock = PTHREAD_RWLOCK_INITIALIZER;
/* Map thread model to string; use only from single-threaded context */
const char *
name_of_thread_model (int model)
{
static char buf[] = "-2147483648 # unknown thread model!";
switch (model) {
case NBDKIT_THREAD_MODEL_SERIALIZE_CONNECTIONS:
return "serialize_connections";
case NBDKIT_THREAD_MODEL_SERIALIZE_ALL_REQUESTS:
return "serialize_all_requests";
case NBDKIT_THREAD_MODEL_SERIALIZE_REQUESTS:
return "serialize_requests";
case NBDKIT_THREAD_MODEL_PARALLEL:
return "parallel";
}
snprintf (buf, sizeof buf, "%d # unknown thread model!", model);
return buf;
}
void
lock_init_thread_model (void)
{
thread_model = top->thread_model (top);
debug ("using thread model: %s", name_of_thread_model (thread_model));
assert (thread_model <= NBDKIT_THREAD_MODEL_PARALLEL);
}
void
lock_connection (void)
{
if (thread_model <= NBDKIT_THREAD_MODEL_SERIALIZE_CONNECTIONS &&
pthread_mutex_lock (&connection_lock))
abort ();
}
void
unlock_connection (void)
{
if (thread_model <= NBDKIT_THREAD_MODEL_SERIALIZE_CONNECTIONS &&
pthread_mutex_unlock (&connection_lock))
abort ();
}
void
lock_request (void)
{
struct connection *conn = threadlocal_get_conn ();
if (thread_model <= NBDKIT_THREAD_MODEL_SERIALIZE_ALL_REQUESTS &&
pthread_mutex_lock (&all_requests_lock))
abort ();
if (conn && thread_model <= NBDKIT_THREAD_MODEL_SERIALIZE_REQUESTS &&
pthread_mutex_lock (&conn->request_lock))
abort ();
if (pthread_rwlock_rdlock (&unload_prevention_lock))
abort ();
}
void
unlock_request (void)
{
struct connection *conn = threadlocal_get_conn ();
if (pthread_rwlock_unlock (&unload_prevention_lock))
abort ();
if (conn && thread_model <= NBDKIT_THREAD_MODEL_SERIALIZE_REQUESTS &&
pthread_mutex_unlock (&conn->request_lock))
abort ();
if (thread_model <= NBDKIT_THREAD_MODEL_SERIALIZE_ALL_REQUESTS &&
pthread_mutex_unlock (&all_requests_lock))
abort ();
}
void
lock_unload (void)
{
if (pthread_rwlock_wrlock (&unload_prevention_lock))
abort ();
}
void
unlock_unload (void)
{
if (pthread_rwlock_unlock (&unload_prevention_lock))
abort ();
}
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