First attempt at FIFO semaphores and PI sems. This may not work...

Before FIFO, everything seemed to be (finally) working ok.

2 files changed, 8 insertions, 2 deletions

diff --git a/arch/i386/kernel/pi_sem_syscalls.c b/arch/i386/kernel/pi_sem_syscalls.c
index 1034c1ccbe..0d1753495e 100644
--- a/arch/i386/kernel/pi_sem_syscalls.c
+++ b/arch/i386/kernel/pi_sem_syscalls.c
@@ -68,7 +68,9 @@ void __sys_pi_down(struct pi_semaphore * sem)
 //              :"+m" (sem->count)
 //              :
 //              :"memory","ax");
-        if (atomic_dec_return(&sem->count) < 0)
+//
+        /* Checking for active waitqueue gives others a chance... */
+        if (atomic_dec_return(&sem->count) < 0 || waitqueue_active(&sem->wait))
                 __pi_down(sem);
 }
 
diff --git a/arch/i386/kernel/sem_syscalls.c b/arch/i386/kernel/sem_syscalls.c
index 274687d21c..4ca92c9be5 100644
--- a/arch/i386/kernel/sem_syscalls.c
+++ b/arch/i386/kernel/sem_syscalls.c
@@ -45,7 +45,11 @@ asmlinkage long sys_down(sema_id sem_id)
         if (sem_id < 0 || sem_id >= MAX_SEMAPHORES)
                 return -EINVAL;
 
-        down(&sems[sem_id]);
+        /* This allows for FIFO sems and gives others a chance... */
+        if (waitqueue_active(&sems[sem_id].wait))
+                __down(&sems[sem_id]);
+        else
+                down(&sems[sem_id]);
         return 0;
 }