* [Qemu-devel] [PATCH] util/qemu-thread-posix.c: Replace OS ifdefs with CONFIG_HAVE_SEM_TIMEDWAIT
@ 2017-09-05 12:19 Peter Maydell
2017-09-05 12:57 ` [Qemu-devel] [Qemu-trivial] " Kamil Rytarowski
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: Peter Maydell @ 2017-09-05 12:19 UTC (permalink / raw)
To: qemu-devel, qemu-trivial; +Cc: patches
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sem_timedwait(), which gets out of date, make configure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
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [Qemu-devel] [Qemu-trivial] [PATCH] util/qemu-thread-posix.c: Replace OS ifdefs with CONFIG_HAVE_SEM_TIMEDWAIT
2017-09-05 12:19 [Qemu-devel] [PATCH] util/qemu-thread-posix.c: Replace OS ifdefs with CONFIG_HAVE_SEM_TIMEDWAIT Peter Maydell
@ 2017-09-05 12:57 ` Kamil Rytarowski
2017-09-05 14:11 ` [Qemu-devel] " Eric Blake
2017-09-14 7:53 ` Michael Tokarev
2 siblings, 0 replies; 4+ messages in thread
From: Kamil Rytarowski @ 2017-09-05 12:57 UTC (permalink / raw)
To: Peter Maydell, qemu-devel, qemu-trivial; +Cc: patches
[-- Attachment #1: Type: text/plain, Size: 4530 bytes --]
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);
>
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Qemu-devel] [PATCH] util/qemu-thread-posix.c: Replace OS ifdefs with CONFIG_HAVE_SEM_TIMEDWAIT
2017-09-05 12:19 [Qemu-devel] [PATCH] util/qemu-thread-posix.c: Replace OS ifdefs with CONFIG_HAVE_SEM_TIMEDWAIT Peter Maydell
2017-09-05 12:57 ` [Qemu-devel] [Qemu-trivial] " Kamil Rytarowski
@ 2017-09-05 14:11 ` Eric Blake
2017-09-14 7:53 ` Michael Tokarev
2 siblings, 0 replies; 4+ messages in thread
From: Eric Blake @ 2017-09-05 14:11 UTC (permalink / raw)
To: Peter Maydell, qemu-devel, qemu-trivial; +Cc: patches
[-- Attachment #1: Type: text/plain, Size: 1398 bytes --]
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
[-- Attachment #2: OpenPGP digital signature --]
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Qemu-devel] [PATCH] util/qemu-thread-posix.c: Replace OS ifdefs with CONFIG_HAVE_SEM_TIMEDWAIT
2017-09-05 12:19 [Qemu-devel] [PATCH] util/qemu-thread-posix.c: Replace OS ifdefs with CONFIG_HAVE_SEM_TIMEDWAIT Peter Maydell
2017-09-05 12:57 ` [Qemu-devel] [Qemu-trivial] " Kamil Rytarowski
2017-09-05 14:11 ` [Qemu-devel] " Eric Blake
@ 2017-09-14 7:53 ` Michael Tokarev
2 siblings, 0 replies; 4+ messages in thread
From: Michael Tokarev @ 2017-09-14 7:53 UTC (permalink / raw)
To: Peter Maydell, qemu-devel, qemu-trivial; +Cc: patches
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
^ permalink raw reply [flat|nested] 4+ messages in thread
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2017-09-05 12:19 [Qemu-devel] [PATCH] util/qemu-thread-posix.c: Replace OS ifdefs with CONFIG_HAVE_SEM_TIMEDWAIT Peter Maydell
2017-09-05 12:57 ` [Qemu-devel] [Qemu-trivial] " Kamil Rytarowski
2017-09-05 14:11 ` [Qemu-devel] " Eric Blake
2017-09-14 7:53 ` Michael Tokarev
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