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sem_timedwait(), which gets out of date, make configure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: Peter Maydell <peter.maydell@linaro.org>
---
It would be nice to gradually reduce the number of places
we do per-OS ifdeffery in favour of checking for the specific
feature we care about in each case...
Tested on Linux, NetBSD, OSX.
configure | 15 +++++++++++++++
include/qemu/thread-posix.h | 2 +-
util/qemu-thread-posix.c | 10 +++++-----
3 files changed, 21 insertions(+), 6 deletions(-)
diff --git a/configure b/configure
index fb7e34a..aa8d4d9 100755
--- a/configure
+++ b/configure
@@ -4448,6 +4448,18 @@ if compile_prog "" "" ; then
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
$python "$source_path/scripts/tracetool.py" "--backends=$trace_backends" --check-backends > /dev/null 2> /dev/null
@@ -5680,6 +5692,9 @@ fi
if test "$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
diff --git a/include/qemu/thread-posix.h b/include/qemu/thread-posix.h
index e5e3a0f..f4296d3 100644
--- a/include/qemu/thread-posix.h
+++ b/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;
diff --git a/util/qemu-thread-posix.c b/util/qemu-thread-posix.c
index 4e95d27..7306475 100644
--- a/util/qemu-thread-posix.c
+++ b/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);
--
2.7.4
On 05.09.2017 14:19, Peter Maydell wrote: > 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. > The NetBSD part looks fine. It builds fine on NetBSD/amd64 8.99.2. All tests pass (with disabled PaX MPROTECT). > Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Kamil Rytarowski <n54@gmx.com> > --- > It would be nice to gradually reduce the number of places > we do per-OS ifdeffery in favour of checking for the specific > feature we care about in each case... > Tested on Linux, NetBSD, OSX. > > configure | 15 +++++++++++++++ > include/qemu/thread-posix.h | 2 +- > util/qemu-thread-posix.c | 10 +++++----- > 3 files changed, 21 insertions(+), 6 deletions(-) > > diff --git a/configure b/configure > index fb7e34a..aa8d4d9 100755 > --- a/configure > +++ b/configure > @@ -4448,6 +4448,18 @@ if compile_prog "" "" ; then > 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 > > $python "$source_path/scripts/tracetool.py" "--backends=$trace_backends" --check-backends > /dev/null 2> /dev/null > @@ -5680,6 +5692,9 @@ fi > if test "$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 > diff --git a/include/qemu/thread-posix.h b/include/qemu/thread-posix.h > index e5e3a0f..f4296d3 100644 > --- a/include/qemu/thread-posix.h > +++ b/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; > diff --git a/util/qemu-thread-posix.c b/util/qemu-thread-posix.c > index 4e95d27..7306475 100644 > --- a/util/qemu-thread-posix.c > +++ b/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); >
On 09/05/2017 07:19 AM, Peter Maydell wrote: > 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: Peter Maydell <peter.maydell@linaro.org> > --- > It would be nice to gradually reduce the number of places > we do per-OS ifdeffery in favour of checking for the specific > feature we care about in each case... Yes, that's always been autoconf's philosophy: feature tests trump platform tests every time, because platforms can add features over time, and because an ifdef on a single feature test is easier to read than a list of platform names. > Tested on Linux, NetBSD, OSX. > Reviewed-by: Eric Blake <eblake@redhat.com> -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
05.09.2017 15:19, Peter Maydell wrote: > 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(). .. Applied to -trivial, thanks! /mjt
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