Futex: turn "int" into "int32_t" for portability

[urcu.git] / urcu-call-rcu-impl.h

diff --git a/urcu-call-rcu-impl.h b/urcu-call-rcu-impl.h
index 69edd49f422dfdbe36524b64f7037ca66cec34fa..8a89295fa44bcc6dc18b84e671ec42705128ff06 100644 (file)
--- a/urcu-call-rcu-impl.h
+++ b/urcu-call-rcu-impl.h
@@ -26,6 +26,7 @@
 #include <signal.h>
 #include <assert.h>
 #include <stdlib.h>
+#include <stdint.h>
 #include <string.h>
 #include <errno.h>
 #include <poll.h>
@@ -39,16 +40,15 @@
 #include "urcu-call-rcu.h"
 #include "urcu-pointer.h"
 #include "urcu/list.h"
-#include "urcu/urcu-futex.h"
+#include "urcu/futex.h"
 
 /* Data structure that identifies a call_rcu thread. */
 
 struct call_rcu_data {
        struct cds_wfq_queue cbs;
        unsigned long flags;
-       pthread_mutex_t mtx;
-       int futex;
-       unsigned long qlen;
+       int32_t futex;
+       unsigned long qlen; /* maintained for debugging. */
        pthread_t tid;
        int cpu_affinity;
        struct cds_list_head list;
@@ -204,6 +204,7 @@ static void *call_rcu_thread(void *arg)
        struct cds_wfq_node **cbs_tail;
        struct call_rcu_data *crdp = (struct call_rcu_data *)arg;
        struct rcu_head *rhp;
+       int rt = !!(uatomic_read(&crdp->flags) & URCU_CALL_RCU_RT);
 
        if (set_thread_cpu_affinity(crdp) != 0) {
                perror("pthread_setaffinity_np");
@@ -211,6 +212,11 @@ static void *call_rcu_thread(void *arg)
        }
 
        thread_call_rcu_data = crdp;
+       if (!rt) {
+               uatomic_dec(&crdp->futex);
+               /* Decrement futex before reading call_rcu list */
+               cmm_smp_mb();
+       }
        for (;;) {
                if (&crdp->cbs.head != _CMM_LOAD_SHARED(crdp->cbs.tail)) {
                        while ((cbs = _CMM_LOAD_SHARED(crdp->cbs.head)) == NULL)
@@ -235,19 +241,34 @@ static void *call_rcu_thread(void *arg)
                        } while (cbs != NULL);
                        uatomic_sub(&crdp->qlen, cbcount);
                }
-               if (crdp->flags & URCU_CALL_RCU_STOP)
+               if (uatomic_read(&crdp->flags) & URCU_CALL_RCU_STOP)
                        break;
-               if (crdp->flags & URCU_CALL_RCU_RT)
-                       poll(NULL, 0, 10);
-               else {
-                       if (&crdp->cbs.head == _CMM_LOAD_SHARED(crdp->cbs.tail))
+               if (!rt) {
+                       if (&crdp->cbs.head
+                           == _CMM_LOAD_SHARED(crdp->cbs.tail)) {
                                call_rcu_wait(crdp);
+                               poll(NULL, 0, 10);
+                               uatomic_dec(&crdp->futex);
+                               /*
+                                * Decrement futex before reading
+                                * call_rcu list.
+                                */
+                               cmm_smp_mb();
+                       } else {
+                               poll(NULL, 0, 10);
+                       }
+               } else {
                        poll(NULL, 0, 10);
                }
        }
-       call_rcu_lock(&crdp->mtx);
-       crdp->flags |= URCU_CALL_RCU_STOPPED;
-       call_rcu_unlock(&crdp->mtx);
+       if (!rt) {
+               /*
+                * Read call_rcu list before write futex.
+                */
+               cmm_smp_mb();
+               uatomic_set(&crdp->futex, 0);
+       }
+       uatomic_or(&crdp->flags, URCU_CALL_RCU_STOPPED);
        return NULL;
 }
 
@@ -271,10 +292,6 @@ static void call_rcu_data_init(struct call_rcu_data **crdpp,
        memset(crdp, '\0', sizeof(*crdp));
        cds_wfq_init(&crdp->cbs);
        crdp->qlen = 0;
-       if (pthread_mutex_init(&crdp->mtx, NULL) != 0) {
-               perror("pthread_mutex_init");
-               exit(-1);
-       }
        crdp->futex = 0;
        crdp->flags = flags;
        cds_list_add(&crdp->list, &call_rcu_data_list);
@@ -557,12 +574,10 @@ void call_rcu_data_free(struct call_rcu_data *crdp)
        if (crdp == NULL || crdp == default_call_rcu_data) {
                return;
        }
-       if ((crdp->flags & URCU_CALL_RCU_STOPPED) == 0) {
-               call_rcu_lock(&crdp->mtx);
-               crdp->flags |= URCU_CALL_RCU_STOP;
-               call_rcu_unlock(&crdp->mtx);
+       if ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_STOPPED) == 0) {
+               uatomic_or(&crdp->flags, URCU_CALL_RCU_STOP);
                wake_call_rcu_thread(crdp);
-               while ((crdp->flags & URCU_CALL_RCU_STOPPED) == 0)
+               while ((uatomic_read(&crdp->flags) & URCU_CALL_RCU_STOPPED) == 0)
                        poll(NULL, 0, 1);
        }
        if (&crdp->cbs.head != _CMM_LOAD_SHARED(crdp->cbs.tail)) {
@@ -646,7 +661,7 @@ void call_rcu_after_fork_child(void)
                if (crdp == default_call_rcu_data)
                        crdp = cds_list_entry(crdp->list.prev,
                                              struct call_rcu_data, list);
-               crdp->flags = URCU_CALL_RCU_STOPPED;
+               uatomic_set(&crdp->flags, URCU_CALL_RCU_STOPPED);
                call_rcu_data_free(crdp);
        }
 }