Re: [PATCH v2 5/8] util: Use unique type for QemuRecMutex in thread-posix.h

[Thomas Huth]

On 15/06/2021 01.31, Richard Henderson wrote:

We will shortly convert lockable.h to _Generic, and we cannot
have two compatible types in the same expansion.  Wrap QemuMutex
in a struct, and unwrap in qemu-thread-posix.c.

Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
---
  include/qemu/thread-posix.h | 10 ++++++++--
  util/qemu-thread-posix.c    | 12 ++++++------
  2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/include/qemu/thread-posix.h b/include/qemu/thread-posix.h
index cf8bc90468..b792e6ef37 100644
--- a/include/qemu/thread-posix.h
+++ b/include/qemu/thread-posix.h
@@ -4,8 +4,6 @@
  #include <pthread.h>
  #include <semaphore.h>

-typedef QemuMutex QemuRecMutex;

-
  struct QemuMutex {
      pthread_mutex_t lock;
  #ifdef CONFIG_DEBUG_MUTEX
@@ -15,6 +13,14 @@ struct QemuMutex {
      bool initialized;
  };

+/*

+ * QemuRecMutex cannot be a typedef of QemuMutex lest we have two
+ * compatible cases in _Generic.  See qemu/lockable.h.
+ */
+typedef struct QemuRecMutex {
+    QemuMutex m;
+} QemuRecMutex;
+
  struct QemuCond {
      pthread_cond_t cond;
      bool initialized;
diff --git a/util/qemu-thread-posix.c b/util/qemu-thread-posix.c
index d990826ed8..fd9d714038 100644
--- a/util/qemu-thread-posix.c
+++ b/util/qemu-thread-posix.c
@@ -116,32 +116,32 @@ void qemu_rec_mutex_init(QemuRecMutex *mutex)

pthread_mutexattr_init(&attr);

      pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
-    err = pthread_mutex_init(&mutex->lock, &attr);
+    err = pthread_mutex_init(&mutex->m.lock, &attr);
      pthread_mutexattr_destroy(&attr);
      if (err) {
          error_exit(err, __func__);
      }
-    mutex->initialized = true;
+    mutex->m.initialized = true;
  }

void qemu_rec_mutex_destroy(QemuRecMutex *mutex)

  {
-    qemu_mutex_destroy(mutex);
+    qemu_mutex_destroy(&mutex->m);
  }

void qemu_rec_mutex_lock_impl(QemuRecMutex *mutex, const char *file, int line)

  {
-    qemu_mutex_lock_impl(mutex, file, line);
+    qemu_mutex_lock_impl(&mutex->m, file, line);
  }

int qemu_rec_mutex_trylock_impl(QemuRecMutex *mutex, const char *file, int line)

  {
-    return qemu_mutex_trylock_impl(mutex, file, line);
+    return qemu_mutex_trylock_impl(&mutex->m, file, line);
  }

void qemu_rec_mutex_unlock_impl(QemuRecMutex *mutex, const char *file, int line)

  {
-    qemu_mutex_unlock_impl(mutex, file, line);
+    qemu_mutex_unlock_impl(&mutex->m, file, line);
  }

void qemu_cond_init(QemuCond *cond)

Reviewed-by: Thomas Huth <th...@redhat.com>