[Xen-changelog] [xen-unstable] minios: add trydown

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1200580855 0
# Node ID a26aee4a152218ba9855f2766bfe6c3846b03074
# Parent  10101bc8181f5f97c641fffade3d1655cdd891fa
minios: add trydown

Signed-off-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxxx>
---
 extras/mini-os/include/semaphore.h |   13 +++++++++++++
 1 files changed, 13 insertions(+)

diff -r 10101bc8181f -r a26aee4a1522 extras/mini-os/include/semaphore.h
--- a/extras/mini-os/include/semaphore.h        Thu Jan 17 14:40:23 2008 +0000
+++ b/extras/mini-os/include/semaphore.h        Thu Jan 17 14:40:55 2008 +0000
@@ -49,6 +49,19 @@ static inline void init_SEMAPHORE(struct
 
 #define init_MUTEX(sem) init_SEMAPHORE(sem, 1)
 
+static inline int trydown(struct semaphore *sem)
+{
+    unsigned long flags;
+    int ret = 0;
+    local_irq_save(flags);
+    if (sem->count > 0) {
+        ret = 1;
+        sem->count--;
+    }
+    local_irq_restore(flags);
+    return ret;
+}
+
 static void inline down(struct semaphore *sem)
 {
     unsigned long flags;

_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-changelog