Support gcc which does not support constructor attribute

- Add call to urcu_init from reader thread registration.
- Try to move the constructor and destructor attribute to the prototype, in case
  gcc has problems with these attributes used with the function definition.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>

diff --git a/urcu.c b/urcu.c
index efbb4b7890a71524fa8264877f3da63565291591..2a225c4ed19d4c626b8f7fb9af5efa702bf3f371 100644 (file)
--- a/urcu.c
+++ b/urcu.c
@@ -36,6 +36,11 @@
 /* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */
 #include "urcu.h"
 
+void __attribute__((constructor)) urcu_init(void);
+void __attribute__((destructor)) urcu_exit(void);
+
+int init_done;
+
 pthread_mutex_t urcu_mutex = PTHREAD_MUTEX_INITIALIZER;
 
 /*
@@ -388,6 +393,7 @@ static void rcu_remove_reader(pthread_t id)
 void rcu_register_thread(void)
 {
        internal_urcu_lock();
+       urcu_init();    /* In case gcc does not support constructor attribute */
        rcu_add_reader(pthread_self());
        internal_urcu_unlock();
 }
@@ -412,11 +418,23 @@ static void sigurcu_handler(int signo, siginfo_t *siginfo, void *context)
        smp_mb();
 }
 
-void __attribute__((constructor)) urcu_init(void)
+/*
+ * urcu_init constructor. Called when the library is linked, but also when
+ * reader threads are calling rcu_register_thread().
+ * Should only be called by a single thread at a given time. This is ensured by
+ * holing the internal_urcu_lock() from rcu_register_thread() or by running at
+ * library load time, which should not be executed by multiple threads nor
+ * concurrently with rcu_register_thread() anyway.
+ */
+void urcu_init(void)
 {
        struct sigaction act;
        int ret;
 
+       if (init_done)
+               return;
+       init_done = 1;
+
        act.sa_sigaction = sigurcu_handler;
        ret = sigaction(SIGURCU, &act, NULL);
        if (ret) {
@@ -425,7 +443,7 @@ void __attribute__((constructor)) urcu_init(void)
        }
 }
 
-void __attribute__((destructor)) urcu_exit(void)
+void urcu_exit(void)
 {
        struct sigaction act;
        int ret;