[RFC v2 3/4] rcu: use coroutine TLS macros

[Stefan Hajnoczi <stefanha@redhat.com>]

RCU may be used from coroutines. Standard __thread variables cannot be
used by coroutines. Use the coroutine TLS macros instead.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 include/qemu/rcu.h         |  7 ++++---
 tests/unit/rcutorture.c    | 10 +++++-----
 tests/unit/test-rcu-list.c |  4 ++--
 util/rcu.c                 | 10 +++++-----
 4 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/include/qemu/rcu.h b/include/qemu/rcu.h
index e69efbd47f..b063c6fde8 100644
--- a/include/qemu/rcu.h
+++ b/include/qemu/rcu.h
@@ -29,6 +29,7 @@
 #include "qemu/atomic.h"
 #include "qemu/notify.h"
 #include "qemu/sys_membarrier.h"
+#include "qemu/coroutine-tls.h"
 
 #ifdef __cplusplus
 extern "C" {
@@ -76,11 +77,11 @@ struct rcu_reader_data {
     NotifierList force_rcu;
 };
 
-extern __thread struct rcu_reader_data rcu_reader;
+QEMU_DECLARE_CO_TLS(struct rcu_reader_data, rcu_reader)
 
 static inline void rcu_read_lock(void)
 {
-    struct rcu_reader_data *p_rcu_reader = &rcu_reader;
+    struct rcu_reader_data *p_rcu_reader = get_ptr_rcu_reader();
     unsigned ctr;
 
     if (p_rcu_reader->depth++ > 0) {
@@ -96,7 +97,7 @@ static inline void rcu_read_lock(void)
 
 static inline void rcu_read_unlock(void)
 {
-    struct rcu_reader_data *p_rcu_reader = &rcu_reader;
+    struct rcu_reader_data *p_rcu_reader = get_ptr_rcu_reader();
 
     assert(p_rcu_reader->depth != 0);
     if (--p_rcu_reader->depth > 0) {
diff --git a/tests/unit/rcutorture.c b/tests/unit/rcutorture.c
index de6f649058..495a4e6f42 100644
--- a/tests/unit/rcutorture.c
+++ b/tests/unit/rcutorture.c
@@ -122,7 +122,7 @@ static void *rcu_read_perf_test(void *arg)
 
     rcu_register_thread();
 
-    *(struct rcu_reader_data **)arg = &rcu_reader;
+    *(struct rcu_reader_data **)arg = get_ptr_rcu_reader();
     qatomic_inc(&nthreadsrunning);
     while (goflag == GOFLAG_INIT) {
         g_usleep(1000);
@@ -148,7 +148,7 @@ static void *rcu_update_perf_test(void *arg)
 
     rcu_register_thread();
 
-    *(struct rcu_reader_data **)arg = &rcu_reader;
+    *(struct rcu_reader_data **)arg = get_ptr_rcu_reader();
     qatomic_inc(&nthreadsrunning);
     while (goflag == GOFLAG_INIT) {
         g_usleep(1000);
@@ -253,7 +253,7 @@ static void *rcu_read_stress_test(void *arg)
 
     rcu_register_thread();
 
-    *(struct rcu_reader_data **)arg = &rcu_reader;
+    *(struct rcu_reader_data **)arg = get_ptr_rcu_reader();
     while (goflag == GOFLAG_INIT) {
         g_usleep(1000);
     }
@@ -304,7 +304,7 @@ static void *rcu_update_stress_test(void *arg)
     struct rcu_stress *cp = qatomic_read(&rcu_stress_current);
 
     rcu_register_thread();
-    *(struct rcu_reader_data **)arg = &rcu_reader;
+    *(struct rcu_reader_data **)arg = get_ptr_rcu_reader();
 
     while (goflag == GOFLAG_INIT) {
         g_usleep(1000);
@@ -347,7 +347,7 @@ static void *rcu_fake_update_stress_test(void *arg)
 {
     rcu_register_thread();
 
-    *(struct rcu_reader_data **)arg = &rcu_reader;
+    *(struct rcu_reader_data **)arg = get_ptr_rcu_reader();
     while (goflag == GOFLAG_INIT) {
         g_usleep(1000);
     }
diff --git a/tests/unit/test-rcu-list.c b/tests/unit/test-rcu-list.c
index 49641e1936..64b81ae058 100644
--- a/tests/unit/test-rcu-list.c
+++ b/tests/unit/test-rcu-list.c
@@ -171,7 +171,7 @@ static void *rcu_q_reader(void *arg)
 
     rcu_register_thread();
 
-    *(struct rcu_reader_data **)arg = &rcu_reader;
+    *(struct rcu_reader_data **)arg = get_ptr_rcu_reader();
     qatomic_inc(&nthreadsrunning);
     while (qatomic_read(&goflag) == GOFLAG_INIT) {
         g_usleep(1000);
@@ -206,7 +206,7 @@ static void *rcu_q_updater(void *arg)
     long long n_removed_local = 0;
     struct list_element *el, *prev_el;
 
-    *(struct rcu_reader_data **)arg = &rcu_reader;
+    *(struct rcu_reader_data **)arg = get_ptr_rcu_reader();
     qatomic_inc(&nthreadsrunning);
     while (qatomic_read(&goflag) == GOFLAG_INIT) {
         g_usleep(1000);
diff --git a/util/rcu.c b/util/rcu.c
index c91da9f137..b6d6c71cff 100644
--- a/util/rcu.c
+++ b/util/rcu.c
@@ -65,7 +65,7 @@ static inline int rcu_gp_ongoing(unsigned long *ctr)
 /* Written to only by each individual reader. Read by both the reader and the
  * writers.
  */
-__thread struct rcu_reader_data rcu_reader;
+QEMU_DEFINE_CO_TLS(struct rcu_reader_data, rcu_reader)
 
 /* Protected by rcu_registry_lock.  */
 typedef QLIST_HEAD(, rcu_reader_data) ThreadList;
@@ -355,23 +355,23 @@ void drain_call_rcu(void)
 
 void rcu_register_thread(void)
 {
-    assert(rcu_reader.ctr == 0);
+    assert(get_ptr_rcu_reader()->ctr == 0);
     qemu_mutex_lock(&rcu_registry_lock);
-    QLIST_INSERT_HEAD(&registry, &rcu_reader, node);
+    QLIST_INSERT_HEAD(&registry, get_ptr_rcu_reader(), node);
     qemu_mutex_unlock(&rcu_registry_lock);
 }
 
 void rcu_unregister_thread(void)
 {
     qemu_mutex_lock(&rcu_registry_lock);
-    QLIST_REMOVE(&rcu_reader, node);
+    QLIST_REMOVE(get_ptr_rcu_reader(), node);
     qemu_mutex_unlock(&rcu_registry_lock);
 }
 
 void rcu_add_force_rcu_notifier(Notifier *n)
 {
     qemu_mutex_lock(&rcu_registry_lock);
-    notifier_list_add(&rcu_reader.force_rcu, n);
+    notifier_list_add(&get_ptr_rcu_reader()->force_rcu, n);
     qemu_mutex_unlock(&rcu_registry_lock);
 }
 
-- 
2.33.1