4 * Userspace RCU library - batch memory reclamation with kernel API
6 * Copyright (c) 2010 Paul E. McKenney <paulmck@linux.vnet.ibm.com>
8 * This library is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
13 * This library is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with this library; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
38 #include "urcu/wfqueue.h"
39 #include "urcu-call-rcu.h"
40 #include "urcu-pointer.h"
41 #include "urcu/list.h"
42 #include "urcu/futex.h"
43 #include "urcu/tls-compat.h"
46 #define SET_AFFINITY_CHECK_PERIOD (1U << 8) /* 256 */
47 #define SET_AFFINITY_CHECK_PERIOD_MASK (SET_AFFINITY_CHECK_PERIOD - 1)
49 /* Data structure that identifies a call_rcu thread. */
51 struct call_rcu_data
{
52 struct cds_wfq_queue cbs
;
55 unsigned long qlen
; /* maintained for debugging. */
58 unsigned long gp_count
;
59 struct cds_list_head list
;
60 } __attribute__((aligned(CAA_CACHE_LINE_SIZE
)));
63 * List of all call_rcu_data structures to keep valgrind happy.
64 * Protected by call_rcu_mutex.
67 CDS_LIST_HEAD(call_rcu_data_list
);
69 /* Link a thread using call_rcu() to its call_rcu thread. */
71 static DEFINE_URCU_TLS(struct call_rcu_data
*, thread_call_rcu_data
);
74 * Guard call_rcu thread creation and atfork handlers.
76 static pthread_mutex_t call_rcu_mutex
= PTHREAD_MUTEX_INITIALIZER
;
78 /* If a given thread does not have its own call_rcu thread, this is default. */
80 static struct call_rcu_data
*default_call_rcu_data
;
83 * If the sched_getcpu() and sysconf(_SC_NPROCESSORS_CONF) calls are
84 * available, then we can have call_rcu threads assigned to individual
85 * CPUs rather than only to specific threads.
88 #ifdef HAVE_SCHED_GETCPU
90 static int urcu_sched_getcpu(void)
92 return sched_getcpu();
95 #else /* #ifdef HAVE_SCHED_GETCPU */
97 static int urcu_sched_getcpu(void)
102 #endif /* #else #ifdef HAVE_SCHED_GETCPU */
104 #if defined(HAVE_SYSCONF) && defined(HAVE_SCHED_GETCPU)
107 * Pointer to array of pointers to per-CPU call_rcu_data structures
108 * and # CPUs. per_cpu_call_rcu_data is a RCU-protected pointer to an
109 * array of RCU-protected pointers to call_rcu_data. call_rcu acts as a
110 * RCU read-side and reads per_cpu_call_rcu_data and the per-cpu pointer
111 * without mutex. The call_rcu_mutex protects updates.
114 static struct call_rcu_data
**per_cpu_call_rcu_data
;
117 static void maxcpus_reset(void)
122 /* Allocate the array if it has not already been allocated. */
124 static void alloc_cpu_call_rcu_data(void)
126 struct call_rcu_data
**p
;
127 static int warned
= 0;
131 maxcpus
= sysconf(_SC_NPROCESSORS_CONF
);
135 p
= malloc(maxcpus
* sizeof(*per_cpu_call_rcu_data
));
137 memset(p
, '\0', maxcpus
* sizeof(*per_cpu_call_rcu_data
));
138 rcu_set_pointer(&per_cpu_call_rcu_data
, p
);
141 fprintf(stderr
, "[error] liburcu: unable to allocate per-CPU pointer array\n");
147 #else /* #if defined(HAVE_SYSCONF) && defined(HAVE_SCHED_GETCPU) */
150 * per_cpu_call_rcu_data should be constant, but some functions below, used both
151 * for cases where cpu number is available and not available, assume it it not
154 static struct call_rcu_data
**per_cpu_call_rcu_data
= NULL
;
155 static const long maxcpus
= -1;
157 static void maxcpus_reset(void)
161 static void alloc_cpu_call_rcu_data(void)
165 #endif /* #else #if defined(HAVE_SYSCONF) && defined(HAVE_SCHED_GETCPU) */
167 /* Acquire the specified pthread mutex. */
169 static void call_rcu_lock(pthread_mutex_t
*pmp
)
173 ret
= pthread_mutex_lock(pmp
);
178 /* Release the specified pthread mutex. */
180 static void call_rcu_unlock(pthread_mutex_t
*pmp
)
184 ret
= pthread_mutex_unlock(pmp
);
190 * Periodically retry setting CPU affinity if we migrate.
191 * Losing affinity can be caused by CPU hotunplug/hotplug, or by
194 #if HAVE_SCHED_SETAFFINITY
196 int set_thread_cpu_affinity(struct call_rcu_data
*crdp
)
201 if (crdp
->cpu_affinity
< 0)
203 if (++crdp
->gp_count
& SET_AFFINITY_CHECK_PERIOD_MASK
)
205 if (urcu_sched_getcpu() == crdp
->cpu_affinity
)
209 CPU_SET(crdp
->cpu_affinity
, &mask
);
210 #if SCHED_SETAFFINITY_ARGS == 2
211 ret
= sched_setaffinity(0, &mask
);
213 ret
= sched_setaffinity(0, sizeof(mask
), &mask
);
216 * EINVAL is fine: can be caused by hotunplugged CPUs, or by
217 * cpuset(7). This is why we should always retry if we detect
220 if (ret
&& errno
== EINVAL
) {
228 int set_thread_cpu_affinity(struct call_rcu_data
*crdp
)
234 static void call_rcu_wait(struct call_rcu_data
*crdp
)
236 /* Read call_rcu list before read futex */
238 if (uatomic_read(&crdp
->futex
) == -1)
239 futex_async(&crdp
->futex
, FUTEX_WAIT
, -1,
243 static void call_rcu_wake_up(struct call_rcu_data
*crdp
)
245 /* Write to call_rcu list before reading/writing futex */
247 if (caa_unlikely(uatomic_read(&crdp
->futex
) == -1)) {
248 uatomic_set(&crdp
->futex
, 0);
249 futex_async(&crdp
->futex
, FUTEX_WAKE
, 1,
254 /* This is the code run by each call_rcu thread. */
256 static void *call_rcu_thread(void *arg
)
258 unsigned long cbcount
;
259 struct cds_wfq_node
*cbs
;
260 struct cds_wfq_node
**cbs_tail
;
261 struct call_rcu_data
*crdp
= (struct call_rcu_data
*)arg
;
262 struct rcu_head
*rhp
;
263 int rt
= !!(uatomic_read(&crdp
->flags
) & URCU_CALL_RCU_RT
);
265 if (set_thread_cpu_affinity(crdp
))
269 * If callbacks take a read-side lock, we need to be registered.
271 rcu_register_thread();
273 URCU_TLS(thread_call_rcu_data
) = crdp
;
275 uatomic_dec(&crdp
->futex
);
276 /* Decrement futex before reading call_rcu list */
280 if (set_thread_cpu_affinity(crdp
))
283 if (uatomic_read(&crdp
->flags
) & URCU_CALL_RCU_PAUSE
) {
285 * Pause requested. Become quiescent: remove
286 * ourself from all global lists, and don't
287 * process any callback. The callback lists may
288 * still be non-empty though.
290 rcu_unregister_thread();
291 cmm_smp_mb__before_uatomic_or();
292 uatomic_or(&crdp
->flags
, URCU_CALL_RCU_PAUSED
);
293 while ((uatomic_read(&crdp
->flags
) & URCU_CALL_RCU_PAUSE
) != 0)
295 uatomic_and(&crdp
->flags
, ~URCU_CALL_RCU_PAUSED
);
296 cmm_smp_mb__after_uatomic_and();
297 rcu_register_thread();
300 if (&crdp
->cbs
.head
!= _CMM_LOAD_SHARED(crdp
->cbs
.tail
)) {
301 while ((cbs
= _CMM_LOAD_SHARED(crdp
->cbs
.head
)) == NULL
)
303 _CMM_STORE_SHARED(crdp
->cbs
.head
, NULL
);
304 cbs_tail
= (struct cds_wfq_node
**)
305 uatomic_xchg(&crdp
->cbs
.tail
, &crdp
->cbs
.head
);
309 while (cbs
->next
== NULL
&&
310 &cbs
->next
!= cbs_tail
)
312 if (cbs
== &crdp
->cbs
.dummy
) {
316 rhp
= (struct rcu_head
*)cbs
;
320 } while (cbs
!= NULL
);
321 uatomic_sub(&crdp
->qlen
, cbcount
);
323 if (uatomic_read(&crdp
->flags
) & URCU_CALL_RCU_STOP
)
325 rcu_thread_offline();
328 == _CMM_LOAD_SHARED(crdp
->cbs
.tail
)) {
331 uatomic_dec(&crdp
->futex
);
333 * Decrement futex before reading
347 * Read call_rcu list before write futex.
350 uatomic_set(&crdp
->futex
, 0);
352 uatomic_or(&crdp
->flags
, URCU_CALL_RCU_STOPPED
);
353 rcu_unregister_thread();
358 * Create both a call_rcu thread and the corresponding call_rcu_data
359 * structure, linking the structure in as specified. Caller must hold
363 static void call_rcu_data_init(struct call_rcu_data
**crdpp
,
367 struct call_rcu_data
*crdp
;
370 crdp
= malloc(sizeof(*crdp
));
373 memset(crdp
, '\0', sizeof(*crdp
));
374 cds_wfq_init(&crdp
->cbs
);
378 cds_list_add(&crdp
->list
, &call_rcu_data_list
);
379 crdp
->cpu_affinity
= cpu_affinity
;
381 cmm_smp_mb(); /* Structure initialized before pointer is planted. */
383 ret
= pthread_create(&crdp
->tid
, NULL
, call_rcu_thread
, crdp
);
389 * Return a pointer to the call_rcu_data structure for the specified
390 * CPU, returning NULL if there is none. We cannot automatically
391 * created it because the platform we are running on might not define
392 * urcu_sched_getcpu().
394 * The call to this function and use of the returned call_rcu_data
395 * should be protected by RCU read-side lock.
398 struct call_rcu_data
*get_cpu_call_rcu_data(int cpu
)
400 static int warned
= 0;
401 struct call_rcu_data
**pcpu_crdp
;
403 pcpu_crdp
= rcu_dereference(per_cpu_call_rcu_data
);
404 if (pcpu_crdp
== NULL
)
406 if (!warned
&& maxcpus
> 0 && (cpu
< 0 || maxcpus
<= cpu
)) {
407 fprintf(stderr
, "[error] liburcu: get CPU # out of range\n");
410 if (cpu
< 0 || maxcpus
<= cpu
)
412 return rcu_dereference(pcpu_crdp
[cpu
]);
416 * Return the tid corresponding to the call_rcu thread whose
417 * call_rcu_data structure is specified.
420 pthread_t
get_call_rcu_thread(struct call_rcu_data
*crdp
)
426 * Create a call_rcu_data structure (with thread) and return a pointer.
429 static struct call_rcu_data
*__create_call_rcu_data(unsigned long flags
,
432 struct call_rcu_data
*crdp
;
434 call_rcu_data_init(&crdp
, flags
, cpu_affinity
);
438 struct call_rcu_data
*create_call_rcu_data(unsigned long flags
,
441 struct call_rcu_data
*crdp
;
443 call_rcu_lock(&call_rcu_mutex
);
444 crdp
= __create_call_rcu_data(flags
, cpu_affinity
);
445 call_rcu_unlock(&call_rcu_mutex
);
450 * Set the specified CPU to use the specified call_rcu_data structure.
452 * Use NULL to remove a CPU's call_rcu_data structure, but it is
453 * the caller's responsibility to dispose of the removed structure.
454 * Use get_cpu_call_rcu_data() to obtain a pointer to the old structure
455 * (prior to NULLing it out, of course).
457 * The caller must wait for a grace-period to pass between return from
458 * set_cpu_call_rcu_data() and call to call_rcu_data_free() passing the
459 * previous call rcu data as argument.
462 int set_cpu_call_rcu_data(int cpu
, struct call_rcu_data
*crdp
)
464 static int warned
= 0;
466 call_rcu_lock(&call_rcu_mutex
);
467 alloc_cpu_call_rcu_data();
468 if (cpu
< 0 || maxcpus
<= cpu
) {
470 fprintf(stderr
, "[error] liburcu: set CPU # out of range\n");
473 call_rcu_unlock(&call_rcu_mutex
);
478 if (per_cpu_call_rcu_data
== NULL
) {
479 call_rcu_unlock(&call_rcu_mutex
);
484 if (per_cpu_call_rcu_data
[cpu
] != NULL
&& crdp
!= NULL
) {
485 call_rcu_unlock(&call_rcu_mutex
);
490 rcu_set_pointer(&per_cpu_call_rcu_data
[cpu
], crdp
);
491 call_rcu_unlock(&call_rcu_mutex
);
496 * Return a pointer to the default call_rcu_data structure, creating
497 * one if need be. Because we never free call_rcu_data structures,
498 * we don't need to be in an RCU read-side critical section.
501 struct call_rcu_data
*get_default_call_rcu_data(void)
503 if (default_call_rcu_data
!= NULL
)
504 return rcu_dereference(default_call_rcu_data
);
505 call_rcu_lock(&call_rcu_mutex
);
506 if (default_call_rcu_data
!= NULL
) {
507 call_rcu_unlock(&call_rcu_mutex
);
508 return default_call_rcu_data
;
510 call_rcu_data_init(&default_call_rcu_data
, 0, -1);
511 call_rcu_unlock(&call_rcu_mutex
);
512 return default_call_rcu_data
;
516 * Return the call_rcu_data structure that applies to the currently
517 * running thread. Any call_rcu_data structure assigned specifically
518 * to this thread has first priority, followed by any call_rcu_data
519 * structure assigned to the CPU on which the thread is running,
520 * followed by the default call_rcu_data structure. If there is not
521 * yet a default call_rcu_data structure, one will be created.
523 * Calls to this function and use of the returned call_rcu_data should
524 * be protected by RCU read-side lock.
526 struct call_rcu_data
*get_call_rcu_data(void)
528 struct call_rcu_data
*crd
;
530 if (URCU_TLS(thread_call_rcu_data
) != NULL
)
531 return URCU_TLS(thread_call_rcu_data
);
534 crd
= get_cpu_call_rcu_data(urcu_sched_getcpu());
539 return get_default_call_rcu_data();
543 * Return a pointer to this task's call_rcu_data if there is one.
546 struct call_rcu_data
*get_thread_call_rcu_data(void)
548 return URCU_TLS(thread_call_rcu_data
);
552 * Set this task's call_rcu_data structure as specified, regardless
553 * of whether or not this task already had one. (This allows switching
554 * to and from real-time call_rcu threads, for example.)
556 * Use NULL to remove a thread's call_rcu_data structure, but it is
557 * the caller's responsibility to dispose of the removed structure.
558 * Use get_thread_call_rcu_data() to obtain a pointer to the old structure
559 * (prior to NULLing it out, of course).
562 void set_thread_call_rcu_data(struct call_rcu_data
*crdp
)
564 URCU_TLS(thread_call_rcu_data
) = crdp
;
568 * Create a separate call_rcu thread for each CPU. This does not
569 * replace a pre-existing call_rcu thread -- use the set_cpu_call_rcu_data()
570 * function if you want that behavior. Should be paired with
571 * free_all_cpu_call_rcu_data() to teardown these call_rcu worker
575 int create_all_cpu_call_rcu_data(unsigned long flags
)
578 struct call_rcu_data
*crdp
;
581 call_rcu_lock(&call_rcu_mutex
);
582 alloc_cpu_call_rcu_data();
583 call_rcu_unlock(&call_rcu_mutex
);
588 if (per_cpu_call_rcu_data
== NULL
) {
592 for (i
= 0; i
< maxcpus
; i
++) {
593 call_rcu_lock(&call_rcu_mutex
);
594 if (get_cpu_call_rcu_data(i
)) {
595 call_rcu_unlock(&call_rcu_mutex
);
598 crdp
= __create_call_rcu_data(flags
, i
);
600 call_rcu_unlock(&call_rcu_mutex
);
604 call_rcu_unlock(&call_rcu_mutex
);
605 if ((ret
= set_cpu_call_rcu_data(i
, crdp
)) != 0) {
606 call_rcu_data_free(crdp
);
608 /* it has been created by other thread */
619 * Wake up the call_rcu thread corresponding to the specified
620 * call_rcu_data structure.
622 static void wake_call_rcu_thread(struct call_rcu_data
*crdp
)
624 if (!(_CMM_LOAD_SHARED(crdp
->flags
) & URCU_CALL_RCU_RT
))
625 call_rcu_wake_up(crdp
);
629 * Schedule a function to be invoked after a following grace period.
630 * This is the only function that must be called -- the others are
631 * only present to allow applications to tune their use of RCU for
632 * maximum performance.
634 * Note that unless a call_rcu thread has not already been created,
635 * the first invocation of call_rcu() will create one. So, if you
636 * need the first invocation of call_rcu() to be fast, make sure
637 * to create a call_rcu thread first. One way to accomplish this is
638 * "get_call_rcu_data();", and another is create_all_cpu_call_rcu_data().
640 * call_rcu must be called by registered RCU read-side threads.
643 void call_rcu(struct rcu_head
*head
,
644 void (*func
)(struct rcu_head
*head
))
646 struct call_rcu_data
*crdp
;
648 cds_wfq_node_init(&head
->next
);
650 /* Holding rcu read-side lock across use of per-cpu crdp */
652 crdp
= get_call_rcu_data();
653 cds_wfq_enqueue(&crdp
->cbs
, &head
->next
);
654 uatomic_inc(&crdp
->qlen
);
655 wake_call_rcu_thread(crdp
);
660 * Free up the specified call_rcu_data structure, terminating the
661 * associated call_rcu thread. The caller must have previously
662 * removed the call_rcu_data structure from per-thread or per-CPU
663 * usage. For example, set_cpu_call_rcu_data(cpu, NULL) for per-CPU
664 * call_rcu_data structures or set_thread_call_rcu_data(NULL) for
665 * per-thread call_rcu_data structures.
667 * We silently refuse to free up the default call_rcu_data structure
668 * because that is where we put any leftover callbacks. Note that
669 * the possibility of self-spawning callbacks makes it impossible
670 * to execute all the callbacks in finite time without putting any
671 * newly spawned callbacks somewhere else. The "somewhere else" of
672 * last resort is the default call_rcu_data structure.
674 * We also silently refuse to free NULL pointers. This simplifies
677 * The caller must wait for a grace-period to pass between return from
678 * set_cpu_call_rcu_data() and call to call_rcu_data_free() passing the
679 * previous call rcu data as argument.
681 void call_rcu_data_free(struct call_rcu_data
*crdp
)
683 struct cds_wfq_node
*cbs
;
684 struct cds_wfq_node
**cbs_tail
;
685 struct cds_wfq_node
**cbs_endprev
;
687 if (crdp
== NULL
|| crdp
== default_call_rcu_data
) {
690 if ((uatomic_read(&crdp
->flags
) & URCU_CALL_RCU_STOPPED
) == 0) {
691 uatomic_or(&crdp
->flags
, URCU_CALL_RCU_STOP
);
692 wake_call_rcu_thread(crdp
);
693 while ((uatomic_read(&crdp
->flags
) & URCU_CALL_RCU_STOPPED
) == 0)
696 if (&crdp
->cbs
.head
!= _CMM_LOAD_SHARED(crdp
->cbs
.tail
)) {
697 while ((cbs
= _CMM_LOAD_SHARED(crdp
->cbs
.head
)) == NULL
)
699 _CMM_STORE_SHARED(crdp
->cbs
.head
, NULL
);
700 cbs_tail
= (struct cds_wfq_node
**)
701 uatomic_xchg(&crdp
->cbs
.tail
, &crdp
->cbs
.head
);
702 /* Create default call rcu data if need be */
703 (void) get_default_call_rcu_data();
704 cbs_endprev
= (struct cds_wfq_node
**)
705 uatomic_xchg(&default_call_rcu_data
->cbs
.tail
,
707 _CMM_STORE_SHARED(*cbs_endprev
, cbs
);
708 uatomic_add(&default_call_rcu_data
->qlen
,
709 uatomic_read(&crdp
->qlen
));
710 wake_call_rcu_thread(default_call_rcu_data
);
713 call_rcu_lock(&call_rcu_mutex
);
714 cds_list_del(&crdp
->list
);
715 call_rcu_unlock(&call_rcu_mutex
);
721 * Clean up all the per-CPU call_rcu threads.
723 void free_all_cpu_call_rcu_data(void)
726 struct call_rcu_data
**crdp
;
727 static int warned
= 0;
732 crdp
= malloc(sizeof(*crdp
) * maxcpus
);
735 fprintf(stderr
, "[error] liburcu: unable to allocate per-CPU pointer array\n");
741 for (cpu
= 0; cpu
< maxcpus
; cpu
++) {
742 crdp
[cpu
] = get_cpu_call_rcu_data(cpu
);
743 if (crdp
[cpu
] == NULL
)
745 set_cpu_call_rcu_data(cpu
, NULL
);
748 * Wait for call_rcu sites acting as RCU readers of the
749 * call_rcu_data to become quiescent.
752 for (cpu
= 0; cpu
< maxcpus
; cpu
++) {
753 if (crdp
[cpu
] == NULL
)
755 call_rcu_data_free(crdp
[cpu
]);
761 * Acquire the call_rcu_mutex in order to ensure that the child sees
762 * all of the call_rcu() data structures in a consistent state. Ensure
763 * that all call_rcu threads are in a quiescent state across fork.
764 * Suitable for pthread_atfork() and friends.
766 void call_rcu_before_fork(void)
768 struct call_rcu_data
*crdp
;
770 call_rcu_lock(&call_rcu_mutex
);
772 cds_list_for_each_entry(crdp
, &call_rcu_data_list
, list
) {
773 uatomic_or(&crdp
->flags
, URCU_CALL_RCU_PAUSE
);
774 cmm_smp_mb__after_uatomic_or();
775 wake_call_rcu_thread(crdp
);
777 cds_list_for_each_entry(crdp
, &call_rcu_data_list
, list
) {
778 while ((uatomic_read(&crdp
->flags
) & URCU_CALL_RCU_PAUSED
) == 0)
784 * Clean up call_rcu data structures in the parent of a successful fork()
785 * that is not followed by exec() in the child. Suitable for
786 * pthread_atfork() and friends.
788 void call_rcu_after_fork_parent(void)
790 struct call_rcu_data
*crdp
;
792 cds_list_for_each_entry(crdp
, &call_rcu_data_list
, list
)
793 uatomic_and(&crdp
->flags
, ~URCU_CALL_RCU_PAUSE
);
794 cds_list_for_each_entry(crdp
, &call_rcu_data_list
, list
) {
795 while ((uatomic_read(&crdp
->flags
) & URCU_CALL_RCU_PAUSED
) != 0)
798 call_rcu_unlock(&call_rcu_mutex
);
802 * Clean up call_rcu data structures in the child of a successful fork()
803 * that is not followed by exec(). Suitable for pthread_atfork() and
806 void call_rcu_after_fork_child(void)
808 struct call_rcu_data
*crdp
, *next
;
810 /* Release the mutex. */
811 call_rcu_unlock(&call_rcu_mutex
);
813 /* Do nothing when call_rcu() has not been used */
814 if (cds_list_empty(&call_rcu_data_list
))
818 * Allocate a new default call_rcu_data structure in order
819 * to get a working call_rcu thread to go with it.
821 default_call_rcu_data
= NULL
;
822 (void)get_default_call_rcu_data();
824 /* Cleanup call_rcu_data pointers before use */
826 free(per_cpu_call_rcu_data
);
827 rcu_set_pointer(&per_cpu_call_rcu_data
, NULL
);
828 URCU_TLS(thread_call_rcu_data
) = NULL
;
831 * Dispose of all of the rest of the call_rcu_data structures.
832 * Leftover call_rcu callbacks will be merged into the new
833 * default call_rcu thread queue.
835 cds_list_for_each_entry_safe(crdp
, next
, &call_rcu_data_list
, list
) {
836 if (crdp
== default_call_rcu_data
)
838 uatomic_set(&crdp
->flags
, URCU_CALL_RCU_STOPPED
);
839 call_rcu_data_free(crdp
);