qemu-thread: Assert locks are initialized before using

Not all platforms check whether a lock is initialized before used.  In
particular Linux seems to be more permissive than OSX.

Check initialization state explicitly in our code to catch such bugs
earlier.

Signed-off-by: Fam Zheng <famz@redhat.com>
Message-Id: <20170704122325.25634-1-famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/util/qemu-thread-posix.c b/util/qemu-thread-posix.c
index eacd99e497..4e95d272dc 100644
--- a/util/qemu-thread-posix.c
+++ b/util/qemu-thread-posix.c
@@ -43,12 +43,15 @@ void qemu_mutex_init(QemuMutex *mutex)
     err = pthread_mutex_init(&mutex->lock, NULL);
     if (err)
         error_exit(err, __func__);
+    mutex->initialized = true;
 }
 
 void qemu_mutex_destroy(QemuMutex *mutex)
 {
     int err;
 
+    assert(mutex->initialized);
+    mutex->initialized = false;
     err = pthread_mutex_destroy(&mutex->lock);
     if (err)
         error_exit(err, __func__);
@@ -58,6 +61,7 @@ void qemu_mutex_lock(QemuMutex *mutex)
 {
     int err;
 
+    assert(mutex->initialized);
     err = pthread_mutex_lock(&mutex->lock);
     if (err)
         error_exit(err, __func__);
@@ -69,6 +73,7 @@ int qemu_mutex_trylock(QemuMutex *mutex)
 {
     int err;
 
+    assert(mutex->initialized);
     err = pthread_mutex_trylock(&mutex->lock);
     if (err == 0) {
         trace_qemu_mutex_locked(mutex);
@@ -84,6 +89,7 @@ void qemu_mutex_unlock(QemuMutex *mutex)
 {
     int err;
 
+    assert(mutex->initialized);
     trace_qemu_mutex_unlocked(mutex);
     err = pthread_mutex_unlock(&mutex->lock);
     if (err)
@@ -102,6 +108,7 @@ void qemu_rec_mutex_init(QemuRecMutex *mutex)
     if (err) {
         error_exit(err, __func__);
     }
+    mutex->initialized = true;
 }
 
 void qemu_cond_init(QemuCond *cond)
@@ -111,12 +118,15 @@ void qemu_cond_init(QemuCond *cond)
     err = pthread_cond_init(&cond->cond, NULL);
     if (err)
         error_exit(err, __func__);
+    cond->initialized = true;
 }
 
 void qemu_cond_destroy(QemuCond *cond)
 {
     int err;
 
+    assert(cond->initialized);
+    cond->initialized = false;
     err = pthread_cond_destroy(&cond->cond);
     if (err)
         error_exit(err, __func__);
@@ -126,6 +136,7 @@ void qemu_cond_signal(QemuCond *cond)
 {
     int err;
 
+    assert(cond->initialized);
     err = pthread_cond_signal(&cond->cond);
     if (err)
         error_exit(err, __func__);
@@ -135,6 +146,7 @@ void qemu_cond_broadcast(QemuCond *cond)
 {
     int err;
 
+    assert(cond->initialized);
     err = pthread_cond_broadcast(&cond->cond);
     if (err)
         error_exit(err, __func__);
@@ -144,6 +156,7 @@ void qemu_cond_wait(QemuCond *cond, QemuMutex *mutex)
 {
     int err;
 
+    assert(cond->initialized);
     trace_qemu_mutex_unlocked(mutex);
     err = pthread_cond_wait(&cond->cond, &mutex->lock);
     trace_qemu_mutex_locked(mutex);
@@ -174,12 +187,15 @@ void qemu_sem_init(QemuSemaphore *sem, int init)
         error_exit(errno, __func__);
     }
 #endif
+    sem->initialized = true;
 }
 
 void qemu_sem_destroy(QemuSemaphore *sem)
 {
     int rc;
 
+    assert(sem->initialized);
+    sem->initialized = false;
 #if defined(__APPLE__) || defined(__NetBSD__)
     rc = pthread_cond_destroy(&sem->cond);
     if (rc < 0) {
@@ -201,6 +217,7 @@ void qemu_sem_post(QemuSemaphore *sem)
 {
     int rc;
 
+    assert(sem->initialized);
 #if defined(__APPLE__) || defined(__NetBSD__)
     pthread_mutex_lock(&sem->lock);
     if (sem->count == UINT_MAX) {
@@ -238,6 +255,7 @@ int qemu_sem_timedwait(QemuSemaphore *sem, int ms)
     int rc;
     struct timespec ts;
 
+    assert(sem->initialized);
 #if defined(__APPLE__) || defined(__NetBSD__)
     rc = 0;
     compute_abs_deadline(&ts, ms);
@@ -285,6 +303,7 @@ void qemu_sem_wait(QemuSemaphore *sem)
 {
     int rc;
 
+    assert(sem->initialized);
 #if defined(__APPLE__) || defined(__NetBSD__)
     pthread_mutex_lock(&sem->lock);
     while (sem->count == 0) {
@@ -310,6 +329,7 @@ void qemu_sem_wait(QemuSemaphore *sem)
 #else
 static inline void qemu_futex_wake(QemuEvent *ev, int n)
 {
+    assert(ev->initialized);
     pthread_mutex_lock(&ev->lock);
     if (n == 1) {
         pthread_cond_signal(&ev->cond);
@@ -321,6 +341,7 @@ static inline void qemu_futex_wake(QemuEvent *ev, int n)
 
 static inline void qemu_futex_wait(QemuEvent *ev, unsigned val)
 {
+    assert(ev->initialized);
     pthread_mutex_lock(&ev->lock);
     if (ev->value == val) {
         pthread_cond_wait(&ev->cond, &ev->lock);
@@ -355,10 +376,13 @@ void qemu_event_init(QemuEvent *ev, bool init)
 #endif
 
     ev->value = (init ? EV_SET : EV_FREE);
+    ev->initialized = true;
 }
 
 void qemu_event_destroy(QemuEvent *ev)
 {
+    assert(ev->initialized);
+    ev->initialized = false;
 #ifndef __linux__
     pthread_mutex_destroy(&ev->lock);
     pthread_cond_destroy(&ev->cond);
@@ -370,6 +394,7 @@ void qemu_event_set(QemuEvent *ev)
     /* qemu_event_set has release semantics, but because it *loads*
      * ev->value we need a full memory barrier here.
      */
+    assert(ev->initialized);
     smp_mb();
     if (atomic_read(&ev->value) != EV_SET) {
         if (atomic_xchg(&ev->value, EV_SET) == EV_BUSY) {
@@ -383,6 +408,7 @@ void qemu_event_reset(QemuEvent *ev)
 {
     unsigned value;
 
+    assert(ev->initialized);
     value = atomic_read(&ev->value);
     smp_mb_acquire();
     if (value == EV_SET) {
@@ -398,6 +424,7 @@ void qemu_event_wait(QemuEvent *ev)
 {
     unsigned value;
 
+    assert(ev->initialized);
     value = atomic_read(&ev->value);
     smp_mb_acquire();
     if (value != EV_SET) {