From: Paolo Bonzini <pbonz...@redhat.com>
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
Reviewed-by: Mike Day <ncm...@ncultra.org>
---
docs/rcu.txt | 13 +++++++------
util/qemu-thread-posix.c | 28 +++++++++++++++++++++++++++-
util/qemu-thread-win32.c | 2 ++
3 files changed, 36 insertions(+), 7 deletions(-)
diff --git a/docs/rcu.txt b/docs/rcu.txt
index 19e4840..5736676 100644
--- a/docs/rcu.txt
+++ b/docs/rcu.txt
@@ -122,8 +122,8 @@ on many POSIX systems other than Linux and Solaris).
For this reason, QEMU's RCU implementation resorts to manual annotation
of "quiescent states", i.e. points where no RCU read-side critical
-section can be active. All threads that participate in the RCU mechanism
-need to annotate such points.
+section can be active. All threads created with qemu_thread_create
+participate in the RCU mechanism and need to annotate such points.
Marking quiescent states is done with the following three APIs:
@@ -144,8 +144,8 @@ Marking quiescent states is done with the following three
APIs:
thread.
-Furthermore, threads that participate in the RCU mechanism must communicate
-this fact using the following APIs:
+The following APIs can be used to use RCU in a thread that is not
+created with qemu_thread_create():
void rcu_register_thread(void);
@@ -160,8 +160,9 @@ this fact using the following APIs:
either manually or by using the QemuCond/QemuSemaphore/QemuEvent
APIs.
-Note that these APIs are relatively heavyweight, and should _not_ be
-nested.
+Note that these APIs are relatively heavyweight, should _not_ be
+nested, and should not be called in threads that are created with
+qemu_thread_create().
DIFFERENCES WITH LINUX
diff --git a/util/qemu-thread-posix.c b/util/qemu-thread-posix.c
index 37dd298..2371176 100644
--- a/util/qemu-thread-posix.c
+++ b/util/qemu-thread-posix.c
@@ -26,6 +26,7 @@
#endif
#include "qemu/thread.h"
#include "qemu/atomic.h"
+#include "qemu/rcu.h"
static void error_exit(int err, const char *msg)
{
@@ -388,6 +389,26 @@ void qemu_event_wait(QemuEvent *ev)
}
+typedef struct QemuThreadData {
+ /* Passed to win32_start_routine. */
+ void *(*start_routine)(void *);
+ void *arg;
+} QemuThreadData;
+
+static void *thread_start_routine(void *arg)
+{
+ QemuThreadData *data = (QemuThreadData *) arg;
+ void *(*start_routine)(void *) = data->start_routine;
+ void *thread_arg = data->arg;
+ void *ret;
+
+ rcu_register_thread();
+ g_free(data);
+ ret = start_routine(thread_arg);
+ rcu_unregister_thread();
+ return ret;
+}
+
void qemu_thread_create(QemuThread *thread,
void *(*start_routine)(void*),
void *arg, int mode)
@@ -395,6 +416,11 @@ void qemu_thread_create(QemuThread *thread,
sigset_t set, oldset;
int err;
pthread_attr_t attr;
+ QemuThreadData *data;
+
+ data = g_malloc(sizeof(*data));
+ data->start_routine = start_routine;
+ data->arg = arg;
err = pthread_attr_init(&attr);
if (err) {
@@ -410,7 +436,7 @@ void qemu_thread_create(QemuThread *thread,
/* Leave signal handling to the iothread. */
sigfillset(&set);
pthread_sigmask(SIG_SETMASK, &set, &oldset);
- err = pthread_create(&thread->thread, &attr, start_routine, arg);
+ err = pthread_create(&thread->thread, &attr, thread_start_routine, data);
if (err)
error_exit(err, __func__);
diff --git a/util/qemu-thread-win32.c b/util/qemu-thread-win32.c
index 27a5217..0c4850d 100644
--- a/util/qemu-thread-win32.c
+++ b/util/qemu-thread-win32.c
@@ -278,6 +278,7 @@ static unsigned __stdcall win32_start_routine(void *arg)
data = NULL;
}
qemu_thread_data = data;
+ rcu_register_thread();
qemu_thread_exit(start_routine(thread_arg));
abort();
}
@@ -293,6 +294,7 @@ void qemu_thread_exit(void *arg)
data->exited = true;
LeaveCriticalSection(&data->cs);
}
+ rcu_unregister_thread();
_endthreadex(0);
}
--
1.8.3.1
