util/qemu-thread-posix.c: Replace OS ifdefs with CONFIG_HAVE_SEM_TIMEDWAIT

In qemu-thread-posix.c we have two implementations of the
various qemu_sem_* functions, one of which uses native POSIX
sem_* and the other of which emulates them with pthread conditions.
This is necessary because not all our host OSes support
sem_timedwait().

Instead of a hard-coded list of OSes which don't implement
sem_timedwait(), which gets out of date, make configure
test for the presence of the function and set a new
CONFIG_HAVE_SEM_TIMEDWAIT appropriately.

In particular, newer NetBSDs have sem_timedwait(), so this
commit will switch them over to using it. OSX still does
not have an implementation.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NKamil Rytarowski <n54@gmx.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NMichael Tokarev <mjt@tls.msk.ru>

configure

@@ -4424,6 +4424,18 @@ if compile_prog "" "" ; then
     posix_syslog=yes
 fi
 
+##########################################
+# check if we have sem_timedwait
+
+sem_timedwait=no
+cat > $TMPC << EOF
+#include <semaphore.h>
+int main(void) { return sem_timedwait(0, 0); }
+EOF
+if compile_prog "" "" ; then
+    sem_timedwait=yes
+fi
+
 ##########################################
 # check if trace backend exists
 
@@ -5678,6 +5690,9 @@ fi
 if test "$inotify1" = "yes" ; then
   echo "CONFIG_INOTIFY1=y" >> $config_host_mak
 fi
+if test "$sem_timedwait" = "yes" ; then
+  echo "CONFIG_SEM_TIMEDWAIT=y" >> $config_host_mak
+fi
 if test "$byteswap_h" = "yes" ; then
   echo "CONFIG_BYTESWAP_H=y" >> $config_host_mak
 fi

include/qemu/thread-posix.h

@@ -21,7 +21,7 @@ struct QemuCond {
 };
 
 struct QemuSemaphore {
-#if defined(__APPLE__) || defined(__NetBSD__)
+#ifndef CONFIG_SEM_TIMEDWAIT
     pthread_mutex_t lock;
     pthread_cond_t cond;
     unsigned int count;

util/qemu-thread-posix.c

@@ -168,7 +168,7 @@ void qemu_sem_init(QemuSemaphore *sem, int init)
 {
     int rc;
 
-#if defined(__APPLE__) || defined(__NetBSD__)
+#ifndef CONFIG_SEM_TIMEDWAIT
     rc = pthread_mutex_init(&sem->lock, NULL);
     if (rc != 0) {
         error_exit(rc, __func__);
@@ -196,7 +196,7 @@ void qemu_sem_destroy(QemuSemaphore *sem)
 
     assert(sem->initialized);
     sem->initialized = false;
-#if defined(__APPLE__) || defined(__NetBSD__)
+#ifndef CONFIG_SEM_TIMEDWAIT
     rc = pthread_cond_destroy(&sem->cond);
     if (rc < 0) {
         error_exit(rc, __func__);
@@ -218,7 +218,7 @@ void qemu_sem_post(QemuSemaphore *sem)
     int rc;
 
     assert(sem->initialized);
-#if defined(__APPLE__) || defined(__NetBSD__)
+#ifndef CONFIG_SEM_TIMEDWAIT
     pthread_mutex_lock(&sem->lock);
     if (sem->count == UINT_MAX) {
         rc = EINVAL;
@@ -256,7 +256,7 @@ int qemu_sem_timedwait(QemuSemaphore *sem, int ms)
     struct timespec ts;
 
     assert(sem->initialized);
-#if defined(__APPLE__) || defined(__NetBSD__)
+#ifndef CONFIG_SEM_TIMEDWAIT
     rc = 0;
     compute_abs_deadline(&ts, ms);
     pthread_mutex_lock(&sem->lock);
@@ -304,7 +304,7 @@ void qemu_sem_wait(QemuSemaphore *sem)
     int rc;
 
     assert(sem->initialized);
-#if defined(__APPLE__) || defined(__NetBSD__)
+#ifndef CONFIG_SEM_TIMEDWAIT
     pthread_mutex_lock(&sem->lock);
     while (sem->count == 0) {
         rc = pthread_cond_wait(&sem->cond, &sem->lock);