Merge remote-tracking branch 'remotes/stefanha/tags/block-pull-request' into staging

# gpg: Signature made Mon 16 Jan 2017 13:38:52 GMT
# gpg:                using RSA key 0x9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>"
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>"
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35  775A 9CA4 ABB3 81AB 73C8

* remotes/stefanha/tags/block-pull-request:
  async: optimize aio_bh_poll
  aio: document locking
  aio-win32: remove walking_handlers, protecting AioHandler list with list_lock
  aio-posix: remove walking_handlers, protecting AioHandler list with list_lock
  aio: tweak walking in dispatch phase
  aio-posix: split aio_dispatch_handlers out of aio_dispatch
  qemu-thread: optimize QemuLockCnt with futexes on Linux
  aio: make ctx->list_lock a QemuLockCnt, subsuming ctx->walking_bh
  qemu-thread: introduce QemuLockCnt
  aio: rename bh_lock to list_lock
  block: get rid of bdrv_io_unplugged_begin/end

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 6 insertions, 29 deletions

diff --git a/util/qemu-thread-posix.c b/util/qemu-thread-posix.c
index d20cddec0c..37cd8ba3fe 100644
--- a/util/qemu-thread-posix.c
+++ b/util/qemu-thread-posix.c
@@ -11,10 +11,6 @@
  *
  */
 #include "qemu/osdep.h"
-#ifdef __linux__
-#include <sys/syscall.h>
-#include <linux/futex.h>
-#endif
 #include "qemu/thread.h"
 #include "qemu/atomic.h"
 #include "qemu/notify.h"
@@ -294,28 +290,9 @@ void qemu_sem_wait(QemuSemaphore *sem)
 }
 
 #ifdef __linux__
-#define futex(...)              syscall(__NR_futex, __VA_ARGS__)
-
-static inline void futex_wake(QemuEvent *ev, int n)
-{
-    futex(ev, FUTEX_WAKE, n, NULL, NULL, 0);
-}
-
-static inline void futex_wait(QemuEvent *ev, unsigned val)
-{
-    while (futex(ev, FUTEX_WAIT, (int) val, NULL, NULL, 0)) {
-        switch (errno) {
-        case EWOULDBLOCK:
-            return;
-        case EINTR:
-            break; /* get out of switch and retry */
-        default:
-            abort();
-        }
-    }
-}
+#include "qemu/futex.h"
 #else
-static inline void futex_wake(QemuEvent *ev, int n)
+static inline void qemu_futex_wake(QemuEvent *ev, int n)
 {
     pthread_mutex_lock(&ev->lock);
     if (n == 1) {
@@ -326,7 +303,7 @@ static inline void futex_wake(QemuEvent *ev, int n)
     pthread_mutex_unlock(&ev->lock);
 }
 
-static inline void futex_wait(QemuEvent *ev, unsigned val)
+static inline void qemu_futex_wait(QemuEvent *ev, unsigned val)
 {
     pthread_mutex_lock(&ev->lock);
     if (ev->value == val) {
@@ -338,7 +315,7 @@ static inline void futex_wait(QemuEvent *ev, unsigned val)
 
 /* Valid transitions:
  * - free->set, when setting the event
- * - busy->set, when setting the event, followed by futex_wake
+ * - busy->set, when setting the event, followed by qemu_futex_wake
  * - set->free, when resetting the event
  * - free->busy, when waiting
  *
@@ -381,7 +358,7 @@ void qemu_event_set(QemuEvent *ev)
     if (atomic_read(&ev->value) != EV_SET) {
         if (atomic_xchg(&ev->value, EV_SET) == EV_BUSY) {
             /* There were waiters, wake them up.  */
-            futex_wake(ev, INT_MAX);
+            qemu_futex_wake(ev, INT_MAX);
         }
     }
 }
@@ -419,7 +396,7 @@ void qemu_event_wait(QemuEvent *ev)
                 return;
             }
         }
-        futex_wait(ev, EV_BUSY);
+        qemu_futex_wait(ev, EV_BUSY);
     }
 }