2 * Copyright (C) 2013-2019 Red Hat Inc.
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions are
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
11 * * Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
15 * * Neither the name of Red Hat nor the names of its contributors may be
16 * used to endorse or promote products derived from this software without
17 * specific prior written permission.
19 * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
21 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
22 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
23 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
24 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
25 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
26 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
27 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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29 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
40 /* Note that the plugin's thread model cannot change after being
41 * loaded, so caching it here is safe.
43 static int thread_model
= -1;
45 static pthread_mutex_t connection_lock
= PTHREAD_MUTEX_INITIALIZER
;
46 static pthread_mutex_t all_requests_lock
= PTHREAD_MUTEX_INITIALIZER
;
47 static pthread_rwlock_t unload_prevention_lock
= PTHREAD_RWLOCK_INITIALIZER
;
50 lock_init_thread_model (void)
52 thread_model
= backend
->thread_model (backend
);
56 lock_connection (void)
58 assert (thread_model
>= 0);
59 if (thread_model
<= NBDKIT_THREAD_MODEL_SERIALIZE_CONNECTIONS
&&
60 pthread_mutex_lock (&connection_lock
))
65 unlock_connection (void)
67 if (thread_model
<= NBDKIT_THREAD_MODEL_SERIALIZE_CONNECTIONS
&&
68 pthread_mutex_unlock (&connection_lock
))
73 lock_request (struct connection
*conn
)
75 assert (thread_model
>= 0);
76 if (thread_model
<= NBDKIT_THREAD_MODEL_SERIALIZE_ALL_REQUESTS
&&
77 pthread_mutex_lock (&all_requests_lock
))
80 if (thread_model
<= NBDKIT_THREAD_MODEL_SERIALIZE_REQUESTS
&&
81 pthread_mutex_lock (&conn
->request_lock
))
84 if (pthread_rwlock_rdlock (&unload_prevention_lock
))
89 unlock_request (struct connection
*conn
)
91 if (pthread_rwlock_unlock (&unload_prevention_lock
))
94 if (thread_model
<= NBDKIT_THREAD_MODEL_SERIALIZE_REQUESTS
&&
95 pthread_mutex_unlock (&conn
->request_lock
))
98 if (thread_model
<= NBDKIT_THREAD_MODEL_SERIALIZE_ALL_REQUESTS
&&
99 pthread_mutex_unlock (&all_requests_lock
))
106 if (pthread_rwlock_wrlock (&unload_prevention_lock
))
113 if (pthread_rwlock_unlock (&unload_prevention_lock
))