| Message ID | 1461987197-31264-7-git-send-email-cota@braap.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 04/29/2016 05:33 PM, Emilio G. Cota wrote: > From: Guillaume Delbergue <guillaume.delbergue@greensocs.com> > > Signed-off-by: Guillaume Delbergue <guillaume.delbergue@greensocs.com> > [Rewritten. - Paolo] > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > [Emilio's additions: use atomic_test_and_set instead of atomic_xchg; > call cpu_relax() while spinning; optimize for uncontended locks by > acquiring the lock with TAS instead of TATAS.] > Signed-off-by: Emilio G. Cota <cota@braap.org> > --- > include/qemu/thread.h | 34 ++++++++++++++++++++++++++++++++++ > 1 file changed, 34 insertions(+) Reviewed-by: Richard Henderson <rth@twiddle.net> r~
diff --git a/include/qemu/thread.h b/include/qemu/thread.h index bdae6df..39ff1ac 100644 --- a/include/qemu/thread.h +++ b/include/qemu/thread.h @@ -1,6 +1,9 @@ #ifndef __QEMU_THREAD_H #define __QEMU_THREAD_H 1 +#include <errno.h> +#include "qemu/processor.h" +#include "qemu/atomic.h" typedef struct QemuMutex QemuMutex; typedef struct QemuCond QemuCond; @@ -60,4 +63,35 @@ struct Notifier; void qemu_thread_atexit_add(struct Notifier *notifier); void qemu_thread_atexit_remove(struct Notifier *notifier); +typedef struct QemuSpin { + int value; +} QemuSpin; + +static inline void qemu_spin_init(QemuSpin *spin) +{ + spin->value = 0; +} + +static inline void qemu_spin_lock(QemuSpin *spin) +{ + while (atomic_test_and_set(&spin->value)) { + while (atomic_read(&spin->value)) { + cpu_relax(); + } + } +} + +static inline int qemu_spin_trylock(QemuSpin *spin) +{ + if (atomic_test_and_set(&spin->value)) { + return -EBUSY; + } + return 0; +} + +static inline void qemu_spin_unlock(QemuSpin *spin) +{ + atomic_mb_set(&spin->value, 0); +} + #endif