Merge spin-lock implementations

Separate spin-lock implementation from lock-implementation and put it into a
non-public header, so it can be re-used by the DDE kit's and Fiasco.OC's
capability-allocator spin lock. Fixes issue #123.

base-foc/include/base/cap_sel_alloc.h

@@ -27,6 +27,7 @@
 #include <util/avl_tree.h>
 #include <base/native_types.h>
 #include <base/printf.h>
+#include <base/lock_guard.h>
 #include <cpu/atomic.h>
 
 /* Fiasco.OC includes */
@@ -80,42 +81,41 @@ namespace Genode
 	Capability_allocator* cap_alloc();
 
 
-	template <unsigned SZ>
-	class Capability_allocator_tpl : public Capability_allocator
-	{
-		private:
-
 	/**
-			 * Low-level lock to protect the allocator
+	 * Low-level spin-lock to protect the allocator
 	 *
 	 * We cannot use a normal Genode lock because this lock is used by code
 	 * executed prior the initialization of Genode.
 	 */
-			class Alloc_lock
+	class Spin_lock
 	{
 		private:
 
-					int _state;
+			volatile int _spinlock;
 
 		public:
 
-					enum State { LOCKED, UNLOCKED };
-
 			/**
 			 * Constructor
 			 */
-					Alloc_lock() : _state(UNLOCKED) {}
+			Spin_lock();
 
-					void lock()
-					{
-						while (!Genode::cmpxchg(&_state, UNLOCKED, LOCKED))
-							Fiasco::l4_ipc_sleep(Fiasco::l4_ipc_timeout(0, 0, 500, 0));
-					}
+			void lock();
+			void unlock();
 
-					void unlock() { _state = UNLOCKED; }
+			/**
+			 * Lock guard
+			 */
+			typedef Genode::Lock_guard<Spin_lock> Guard;
 	};
 
 
+
+	template <unsigned SZ>
+	class Capability_allocator_tpl : public Capability_allocator
+	{
+		private:
+
 			/**
 			 * Node in the capability cache,
 			 * associates global cap ids with kernel-capabilities.
@@ -156,7 +156,7 @@ namespace Genode
 			addr_t             _cap_idx;  /* start cap-selector */
 			Cap_node           _data[SZ]; /* cache-nodes backing store */
 			Avl_tree<Cap_node> _tree;     /* cap cache */
-			Alloc_lock         _lock;
+			Spin_lock          _lock;
 
 		public:
 
@@ -173,10 +173,10 @@ namespace Genode
 
 			addr_t alloc(size_t num_caps)
 			{
-				_lock.lock();
+				Spin_lock::Guard guard(_lock);
+
 				int ret_base = _cap_idx;
 				_cap_idx += num_caps * Fiasco::L4_CAP_SIZE;
-				_lock.unlock();
 				return ret_base;
 			}
 
@@ -208,7 +208,7 @@ namespace Genode
 
 			void free(addr_t cap, size_t num_caps)
 			{
-				_lock.lock();
+				Spin_lock::Guard guard(_lock);
 
 				for (unsigned i = 0; i < SZ; i++)
 					if (!_data[i]._kcap == cap) {
@@ -217,7 +217,6 @@ namespace Genode
 						_data[i]._id   = 0;
 						break;
 					}
-				_lock.unlock();
 			}
 	};
 }

base-foc/lib/mk/env.mk

@@ -1,7 +1,10 @@
-SRC_CC = env.cc context_area.cc cap_sel_alloc.cc reload_parent_cap.cc
+SRC_CC   = env.cc context_area.cc cap_sel_alloc.cc \
+           reload_parent_cap.cc spin_lock.cc
 LIBS     = ipc heap log_console lock
+INC_DIR += $(REP_DIR)/src/base/lock $(BASE_DIR)/src/base/lock
 
 vpath env.cc               $(BASE_DIR)/src/base/env
 vpath context_area.cc      $(BASE_DIR)/src/base/env
 vpath cap_sel_alloc.cc     $(REP_DIR)/src/base/env
 vpath reload_parent_cap.cc $(BASE_DIR)/src/base/env
+vpath spin_lock.cc         $(REP_DIR)/src/base/env

base-foc/src/base/env/spin_lock.cc

@@ -0,0 +1,29 @@
+/*
+ * \brief  Spin-lock implementation for environment's capability -allocator.
+ * \author Stefan Kalkowski
+ * \date   2012-02-29
+ *
+ * This is a Fiasco.OC-specific addition to the process enviroment.
+ */
+
+/*
+ * Copyright (C) 2012 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU General Public License version 2.
+ */
+
+/* Genode includes */
+#include <base/cap_sel_alloc.h>
+
+/* Lock implementation local include */
+#include <spin_lock.h>
+
+
+Genode::Spin_lock::Spin_lock() : _spinlock(SPINLOCK_UNLOCKED) {}
+
+
+void Genode::Spin_lock::lock()   { spinlock_lock(&_spinlock);   }
+
+
+void Genode::Spin_lock::unlock() { spinlock_unlock(&_spinlock); }

base-foc/src/base/lock/lock_helper.h

@@ -15,6 +15,9 @@
  * under the terms of the GNU General Public License version 2.
  */
 
+#ifndef _INCLUDE__BASE__LOCK__LOCK_HELPER_H_
+#define _INCLUDE__BASE__LOCK__LOCK_HELPER_H_
+
 /* Genode includes */
 #include <base/native_types.h>
 #include <base/thread.h>
@@ -106,3 +109,5 @@ static inline void thread_stop_myself()
 	                               + Fiasco_capability::THREAD_IRQ_CAP;
 	l4_irq_receive(irq, L4_IPC_NEVER);
 }
+
+#endif /* _INCLUDE__BASE__LOCK__LOCK_HELPER_H_ */

base-foc/src/core/target.inc

@@ -32,10 +32,13 @@ SRC_CC       = main.cc \
                context_area.cc \
                cap_session_component.cc \
                cpu_session_extension.cc \
-               pd_session_extension.cc
+               pd_session_extension.cc \
+               spin_lock.cc
 
 INC_DIR     += $(REP_DIR)/src/core/include \
-               $(GEN_CORE_DIR)/include
+               $(GEN_CORE_DIR)/include \
+               $(REP_DIR)/src/base/lock \
+               $(BASE_DIR)/src/base/lock
 
 vpath main.cc                     $(GEN_CORE_DIR)
 vpath multiboot_info.cc           $(GEN_CORE_DIR)
@@ -52,4 +55,5 @@ vpath dump_alloc.cc               $(GEN_CORE_DIR)
 vpath context_area.cc             $(GEN_CORE_DIR)
 vpath thread.cc                   $(REP_DIR)/src/base/thread
 vpath thread_bootstrap.cc         $(REP_DIR)/src/base/thread
+vpath spin_lock.cc                $(REP_DIR)/src/base/env
 vpath %.cc                        $(REP_DIR)/src/core

base/src/base/lock/lock.cc

@@ -13,55 +13,18 @@
 
 /* Genode includes */
 #include <base/cancelable_lock.h>
-#include <base/printf.h>
-#include <cpu/atomic.h>
 
 /* local includes */
-#include <lock_helper.h>
+#include "spin_lock.h"
 
 using namespace Genode;
 
-
 /**
  * Track interesting lock conditions, counters are only used for testing
  */
-int debug_spinlock_contention_cnt;
 int debug_lock_sleep_race_cnt;
 
 
-/***************
- ** Utilities **
- ***************/
-
-/*
- * Spinlock functions used for protecting the critical sections within the
- * 'lock' and 'unlock' functions. Contention in these short-running code
- * portions is rare but is must be considered.
- */
-
-enum State { SPINLOCK_LOCKED, SPINLOCK_UNLOCKED };
-
-static inline void spinlock_lock(volatile int *lock_variable)
-{
-	while (!cmpxchg(lock_variable, SPINLOCK_UNLOCKED, SPINLOCK_LOCKED)) {
-
-		debug_spinlock_contention_cnt++;  /* only for statistics */
-
-		/*
-		 * Yield our remaining time slice to help the spinlock holder to pass
-		 * the critical section.
-		 */
-		thread_yield();
-	}
-}
-
-
-static inline void spinlock_unlock(volatile int *lock_variable)
-{
-	*lock_variable = SPINLOCK_UNLOCKED;
-}
-
-
 /********************
  ** Lock applicant **
  ********************/

base/src/base/lock/spin_lock.h

@@ -0,0 +1,49 @@
+/*
+ * \brief  Spin lock implementation
+ * \author Norman Feske
+ * \author Stefan Kalkowski
+ * \date   2009-03-25
+ */
+
+/*
+ * Copyright (C) 2009-2012 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU General Public License version 2.
+ */
+
+#ifndef _INCLUDE__BASE__LOCK__SPIN_H_
+#define _INCLUDE__BASE__LOCK__SPIN_H_
+
+/* Genode includes */
+#include <cpu/atomic.h>
+
+/* local includes */
+#include <lock_helper.h>
+
+/*
+ * Spinlock functions used for protecting the critical sections within the
+ * 'lock' and 'unlock' functions. Contention in these short-running code
+ * portions is rare but is must be considered.
+ */
+
+enum State { SPINLOCK_LOCKED, SPINLOCK_UNLOCKED };
+
+static inline void spinlock_lock(volatile int *lock_variable)
+{
+	while (!Genode::cmpxchg(lock_variable, SPINLOCK_UNLOCKED, SPINLOCK_LOCKED)) {
+		/*
+		 * Yield our remaining time slice to help the spinlock holder to pass
+		 * the critical section.
+		 */
+		thread_yield();
+	}
+}
+
+
+static inline void spinlock_unlock(volatile int *lock_variable)
+{
+	*lock_variable = SPINLOCK_UNLOCKED;
+}
+
+#endif /* _INCLUDE__BASE__LOCK__SPIN_H_ */

os/include/dde_kit/spin_lock.h

@@ -19,9 +19,6 @@
  */
 typedef volatile int dde_kit_spin_lock;
 
-enum { DDE_KIT_SPIN_LOCK_LOCKED, DDE_KIT_SPIN_LOCK_UNLOCKED };
-
-
 /**
  * Initialize spin lock
  *

os/lib/mk/dde_kit.mk

@@ -1,6 +1,7 @@
 SRC_C        = lock.cc semaphore.cc panic.cc printf.cc interrupt.cc pgtab.cc \
                memory.cc thread.cc pci_tree.cc pci.cc resources.cc timer.cc \
                dde_kit.cc spin_lock.cc
-LIBS     = thread alarm
+LIBS         = thread alarm lock
+REP_INC_DIR += src/base/lock
 
 vpath % $(REP_DIR)/src/lib/dde_kit

os/src/lib/dde_kit/spin_lock.cc

@@ -15,21 +15,16 @@
 #include <cpu/atomic.h>
 #include <base/printf.h>
 
+#include <spin_lock.h>
+
 extern "C" {
 #include <dde_kit/spin_lock.h>
 }
 
 
-static inline void spinlock_lock(volatile int *lock_variable)
-{
-	while (!Genode::cmpxchg(lock_variable, DDE_KIT_SPIN_LOCK_UNLOCKED,
-	                                       DDE_KIT_SPIN_LOCK_LOCKED));
-}
-
-
 extern "C" void dde_kit_spin_lock_init(dde_kit_spin_lock *spin_lock)
 {
-	*spin_lock = DDE_KIT_SPIN_LOCK_UNLOCKED;
+	*spin_lock = SPINLOCK_UNLOCKED;
 }
 
 
@@ -52,6 +47,6 @@ extern "C" int dde_kit_spin_lock_try_lock(dde_kit_spin_lock *spin_lock)
 
 extern "C" void dde_kit_spin_lock_unlock(dde_kit_spin_lock *spin_lock)
 {
-	*spin_lock = DDE_KIT_SPIN_LOCK_UNLOCKED;
+	spinlock_unlock(spin_lock);
 }