This commit was manufactured by cvs2svn to create branch 'vserver'.

[linux-2.6.git] / arch / powerpc / lib / locks.c

diff --git a/arch/powerpc/lib/locks.c b/arch/powerpc/lib/locks.c
new file mode 100644 (file)
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+++ b/arch/powerpc/lib/locks.c
@@ -0,0 +1,93 @@
+/*
+ * Spin and read/write lock operations.
+ *
+ * Copyright (C) 2001-2004 Paul Mackerras <paulus@au.ibm.com>, IBM
+ * Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
+ * Copyright (C) 2002 Dave Engebretsen <engebret@us.ibm.com>, IBM
+ *   Rework to support virtual processors
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/spinlock.h>
+#include <linux/module.h>
+#include <linux/stringify.h>
+#include <linux/smp.h>
+
+/* waiting for a spinlock... */
+#if defined(CONFIG_PPC_SPLPAR) || defined(CONFIG_PPC_ISERIES)
+#include <asm/hvcall.h>
+#include <asm/iseries/hv_call.h>
+#include <asm/smp.h>
+
+void __spin_yield(raw_spinlock_t *lock)
+{
+       unsigned int lock_value, holder_cpu, yield_count;
+
+       lock_value = lock->slock;
+       if (lock_value == 0)
+               return;
+       holder_cpu = lock_value & 0xffff;
+       BUG_ON(holder_cpu >= NR_CPUS);
+       yield_count = lppaca[holder_cpu].yield_count;
+       if ((yield_count & 1) == 0)
+               return;         /* virtual cpu is currently running */
+       rmb();
+       if (lock->slock != lock_value)
+               return;         /* something has changed */
+#ifdef CONFIG_PPC_ISERIES
+       HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc,
+               ((u64)holder_cpu << 32) | yield_count);
+#else
+       plpar_hcall_norets(H_CONFER, get_hard_smp_processor_id(holder_cpu),
+                          yield_count);
+#endif
+}
+
+/*
+ * Waiting for a read lock or a write lock on a rwlock...
+ * This turns out to be the same for read and write locks, since
+ * we only know the holder if it is write-locked.
+ */
+void __rw_yield(raw_rwlock_t *rw)
+{
+       int lock_value;
+       unsigned int holder_cpu, yield_count;
+
+       lock_value = rw->lock;
+       if (lock_value >= 0)
+               return;         /* no write lock at present */
+       holder_cpu = lock_value & 0xffff;
+       BUG_ON(holder_cpu >= NR_CPUS);
+       yield_count = lppaca[holder_cpu].yield_count;
+       if ((yield_count & 1) == 0)
+               return;         /* virtual cpu is currently running */
+       rmb();
+       if (rw->lock != lock_value)
+               return;         /* something has changed */
+#ifdef CONFIG_PPC_ISERIES
+       HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc,
+               ((u64)holder_cpu << 32) | yield_count);
+#else
+       plpar_hcall_norets(H_CONFER, get_hard_smp_processor_id(holder_cpu),
+                          yield_count);
+#endif
+}
+#endif
+
+void __raw_spin_unlock_wait(raw_spinlock_t *lock)
+{
+       while (lock->slock) {
+               HMT_low();
+               if (SHARED_PROCESSOR)
+                       __spin_yield(lock);
+       }
+       HMT_medium();
+}
+
+EXPORT_SYMBOL(__raw_spin_unlock_wait);