Re: [Qemu-devel] [PATCH 05/10] include: add spinlock wrapper

[Paolo Bonzini <pbonzini@redhat.com>]

On 05/04/2016 07:30, Emilio G. Cota wrote:
> Wrap pthread_spin on POSIX, or QemuMutex on Windows.
> 
> AFAIK there are is no off-the-shelf spinlock implementation for
> Windows, so we'll just use QemuMutex.

It's much simpler to use a simple test-and-set spinlock.

GitHub is down, but this should be the link
http://github.com/bonzini/qemu/commit/e1361634 (it's in my mttcg branch).

Paolo

> Signed-off-by: Emilio G. Cota <cota@braap.org>
> ---
>  include/qemu/spinlock-posix.h | 60 +++++++++++++++++++++++++++++++++++++++++++
>  include/qemu/spinlock-win32.h | 33 ++++++++++++++++++++++++
>  include/qemu/spinlock.h       | 10 ++++++++
>  3 files changed, 103 insertions(+)
>  create mode 100644 include/qemu/spinlock-posix.h
>  create mode 100644 include/qemu/spinlock-win32.h
>  create mode 100644 include/qemu/spinlock.h
> 
> diff --git a/include/qemu/spinlock-posix.h b/include/qemu/spinlock-posix.h
> new file mode 100644
> index 0000000..51c2c08
> --- /dev/null
> +++ b/include/qemu/spinlock-posix.h
> @@ -0,0 +1,60 @@
> +#ifndef QEMU_SPINLOCK_POSIX_H
> +#define QEMU_SPINLOCK_POSIX_H
> +
> +#include <qemu/thread.h>
> +#include <qemu/osdep.h>
> +
> +typedef pthread_spinlock_t QemuSpinLock;
> +
> +static inline void qemu_spinlock_error_exit(int err, const char *msg)
> +{
> +    fprintf(stderr, "qemu: %s: %s\n", msg, strerror(err));
> +    abort();
> +}
> +
> +static inline void qemu_spinlock_init(QemuSpinLock *lock)
> +{
> +    int rc;
> +
> +    rc = pthread_spin_init(lock, PTHREAD_PROCESS_SHARED);
> +    if (unlikely(rc)) {
> +        qemu_spinlock_error_exit(rc, __func__);
> +    }
> +}
> +
> +static inline void qemu_spinlock_destroy(QemuSpinLock *lock)
> +{
> +    int rc;
> +
> +    rc = pthread_spin_destroy(lock);
> +    if (unlikely(rc)) {
> +        qemu_spinlock_error_exit(rc, __func__);
> +    }
> +}
> +
> +static inline void qemu_spinlock_lock(QemuSpinLock *lock)
> +{
> +    int rc;
> +
> +    rc = pthread_spin_lock(lock);
> +    if (unlikely(rc)) {
> +        qemu_spinlock_error_exit(rc, __func__);
> +    }
> +}
> +
> +static inline int qemu_spinlock_trylock(QemuSpinLock *lock)
> +{
> +    return pthread_spin_trylock(lock);
> +}
> +
> +static inline void qemu_spinlock_unlock(QemuSpinLock *lock)
> +{
> +    int rc;
> +
> +    rc = pthread_spin_unlock(lock);
> +    if (unlikely(rc)) {
> +        qemu_spinlock_error_exit(rc, __func__);
> +    }
> +}
> +
> +#endif /* QEMU_SPINLOCK_POSIX_H */
> diff --git a/include/qemu/spinlock-win32.h b/include/qemu/spinlock-win32.h
> new file mode 100644
> index 0000000..5a105fb
> --- /dev/null
> +++ b/include/qemu/spinlock-win32.h
> @@ -0,0 +1,33 @@
> +#ifndef QEMU_SPINLOCK_WIN32_H
> +#define QEMU_SPINLOCK_WIN32_H
> +
> +#include <qemu/thread.h>
> +
> +typedef QemuMutex QemuSpinLock;
> +
> +static inline void qemu_spinlock_init(QemuSpinLock *lock)
> +{
> +    qemu_mutex_init(lock);
> +}
> +
> +static inline void qemu_spinlock_destroy(QemuSpinLock *lock)
> +{
> +    qemu_mutex_destroy(lock);
> +}
> +
> +static inline void qemu_spinlock_lock(QemuSpinLock *lock)
> +{
> +    qemu_mutex_lock(lock);
> +}
> +
> +static inline int qemu_spinlock_trylock(QemuSpinLock *lock)
> +{
> +    return qemu_mutex_trylock(lock);
> +}
> +
> +static inline void qemu_spinlock_unlock(QemuSpinLock *lock)
> +{
> +    qemu_mutex_unlock(lock);
> +}
> +
> +#endif /* QEMU_SPINLOCK_WIN32_H */
> diff --git a/include/qemu/spinlock.h b/include/qemu/spinlock.h
> new file mode 100644
> index 0000000..001b55e
> --- /dev/null
> +++ b/include/qemu/spinlock.h
> @@ -0,0 +1,10 @@
> +#ifndef QEMU_SPINLOCK_H
> +#define QEMU_SPINLOCK_H
> +
> +#ifdef _WIN32
> +#include "spinlock-win32.h"
> +#else
> +#include "spinlock-posix.h"
> +#endif
> +
> +#endif /* QEMU_SPINLOCK_H */
>