* invalidate any other reasons why the executable file might be covered by
* the GNU General Public License.
*
- * Copyright 2001,2004 Develer S.r.l. (http://www.develer.com/)
- * Copyright 1999,2000,2001 Bernie Innocenti <bernie@codewiz.org>
- *
+ * Copyright 2001, 2004 Develer S.r.l. (http://www.develer.com/)
+ * Copyright 1999, 2000, 2001, 2008 Bernie Innocenti <bernie@codewiz.org>
* -->
*
- * \brief Process scheduler (public interface).
+ * \brief Bertos Kernel core (Process scheduler).
*
* \version $Id$
- *
* \author Bernie Innocenti <bernie@codewiz.org>
+ *
+ * $WIZ$ module_name = "kernel"
+ * $WIZ$ module_configuration = "bertos/cfg/cfg_proc.h"
+ * $WIZ$ module_depends = "switch_ctx"
*/
+
#ifndef KERN_PROC_H
#define KERN_PROC_H
-#include "cfg/cfg_kern.h"
+#include "cfg/cfg_proc.h"
+#include "cfg/cfg_monitor.h"
+
#include <cfg/compiler.h>
-#include <cpu/irq.h>
+#if CONFIG_KERN_PREEMPT
+ #include <cfg/debug.h> // ASSERT()
+#endif
+
+#include <cpu/types.h> // cpu_stack_t
+#include <cpu/frame.h> // CPU_SAVED_REGS_CNT
-/* Fwd decl */
+/*
+ * Forward declaration. The definition of struct Process is private to the
+ * scheduler and hidden in proc_p.h.
+ */
struct Process;
-/* Task scheduling services */
void proc_init(void);
-struct Process *proc_new_with_name(const char* name, void (*entry)(void), iptr_t data, size_t stacksize, cpustack_t *stack);
+struct Process *proc_new_with_name(const char *name, void (*entry)(void), iptr_t data, size_t stacksize, cpu_stack_t *stack);
#if !CONFIG_KERN_MONITOR
#define proc_new(entry,data,size,stack) proc_new_with_name(NULL,(entry),(data),(size),(stack))
void proc_exit(void);
void proc_yield(void);
-#define proc_switch proc_yield /* OBSOLETE */
+void proc_rename(struct Process *proc, const char *name);
+const char *proc_name(struct Process *proc);
+const char *proc_currentName(void);
+iptr_t proc_currentUserData(void);
int proc_testSetup(void);
int proc_testRun(void);
int proc_testTearDown(void);
-struct Process *proc_current(void);
-iptr_t proc_current_user_data(void);
-void proc_rename(struct Process *proc, const char* name);
+/**
+ * Return the context structure of the currently running process.
+ *
+ * The details of the Process structure are private to the scheduler.
+ * The address returned by this function is an opaque pointer that can
+ * be passed as an argument to other process-related functions.
+ */
+INLINE struct Process *proc_current(void)
+{
+ extern struct Process *CurrentProcess;
+ return CurrentProcess;
+}
-#if CONFIG_KERN_PREEMPT
- void proc_forbid(void);
- void proc_permit(void);
+#if CONFIG_KERN_PRI
+ void proc_setPri(struct Process *proc, int pri);
#else
- INLINE void proc_forbid(void) { /* nop */ }
- INLINE void proc_permit(void) { /* nop */ }
+ INLINE void proc_setPri(UNUSED_ARG(struct Process *,proc), UNUSED_ARG(int, pri))
+ {
+ }
#endif
+/**
+ * Disable preemptive task switching.
+ *
+ * The scheduler maintains a global nesting counter. Task switching is
+ * effectively re-enabled only when the number of calls to proc_permit()
+ * matches the number of calls to proc_forbid().
+ *
+ * \note Calling functions that could sleep while task switching is disabled
+ * is dangerous and unsupported.
+ *
+ * \note calling proc_forbid() from within an interrupt is illegal and
+ * meaningless.
+ *
+ * \note proc_permit() expands inline to 1-2 asm instructions, so it's a
+ * very efficient locking primitive in simple but performance-critical
+ * situations. In all other cases, semaphores offer a more flexible and
+ * fine-grained locking primitive.
+ *
+ * \sa proc_permit()
+ */
+INLINE void proc_forbid(void)
+{
+ #if CONFIG_KERN_PREEMPT
+ extern cpu_atomic_t _preempt_forbid_cnt;
+ /*
+ * We don't need to protect the counter against other processes.
+ * The reason why is a bit subtle.
+ *
+ * If a process gets here, preempt_forbid_cnt can be either 0,
+ * or != 0. In the latter case, preemption is already disabled
+ * and no concurrency issues can occur.
+ *
+ * In the former case, we could be preempted just after reading the
+ * value 0 from memory, and a concurrent process might, in fact,
+ * bump the value of preempt_forbid_cnt under our nose!
+ *
+ * BUT: if this ever happens, then we won't get another chance to
+ * run until the other process calls proc_permit() to re-enable
+ * preemption. At this point, the value of preempt_forbid_cnt
+ * must be back to 0, and thus what we had originally read from
+ * memory happens to be valid.
+ *
+ * No matter how hard you think about it, and how complicated you
+ * make your scenario, the above holds true as long as
+ * "preempt_forbid_cnt != 0" means that no task switching is
+ * possible.
+ */
+ ++_preempt_forbid_cnt;
+
+ /*
+ * Make sure _preempt_forbid_cnt is flushed to memory so the
+ * preemption softirq will see the correct value from now on.
+ */
+ MEMORY_BARRIER;
+ #endif
+}
+
+/**
+ * Re-enable preemptive task switching.
+ *
+ * \sa proc_forbid()
+ */
+INLINE void proc_permit(void)
+{
+ #if CONFIG_KERN_PREEMPT
+
+ /*
+ * This is to ensure any global state changed by the process gets
+ * flushed to memory before task switching is re-enabled.
+ */
+ MEMORY_BARRIER;
+ extern cpu_atomic_t _preempt_forbid_cnt;
+ /* No need to protect against interrupts here. */
+ ASSERT(_preempt_forbid_cnt != 0);
+ --_preempt_forbid_cnt;
+
+ /*
+ * This ensures _preempt_forbid_cnt is flushed to memory immediately
+ * so the preemption interrupt sees the correct value.
+ */
+ MEMORY_BARRIER;
+
+ #endif
+}
+
+/**
+ * \return true if preemptive task switching is allowed.
+ * \note This accessor is needed because _preempt_forbid_cnt
+ * must be absoultely private.
+ */
+INLINE bool proc_allowed(void)
+{
+ #if CONFIG_KERN_PREEMPT
+ extern cpu_atomic_t _preempt_forbid_cnt;
+ return (_preempt_forbid_cnt == 0);
+ #else
+ return true;
+ #endif
+}
+
/**
* Execute a block of \a CODE atomically with respect to task scheduling.
*/
proc_permit(); \
} while(0)
-#ifndef CONFIG_PROC_DEFSTACKSIZE
+#ifndef CONFIG_KERN_MINSTACKSIZE
#if (ARCH & ARCH_EMUL)
/* We need a large stack because system libraries are bloated */
- #define CONFIG_PROC_DEFSTACKSIZE 65536
+ #define CONFIG_KERN_MINSTACKSIZE 65536
#else
/**
* Default stack size for each thread, in bytes.
* required per process. Use irqmanager to minimize stack
* usage.
*/
- #define CONFIG_PROC_DEFSTACKSIZE \
- (CPU_SAVED_REGS_CNT * 2 * sizeof(cpustack_t) \
- + 32 * sizeof(int))
+ #define CONFIG_KERN_MINSTACKSIZE \
+ (CPU_SAVED_REGS_CNT * 2 * sizeof(cpu_stack_t) \
+ + 48 * sizeof(int))
#endif
#endif
#if CONFIG_KERN_MONITOR
#include <cpu/types.h>
#if (SIZEOF_CPUSTACK_T == 1)
- /* 8bit cpustack_t */
+ /* 8bit cpu_stack_t */
#define CONFIG_KERN_STACKFILLCODE 0xA5
#define CONFIG_KERN_MEMFILLCODE 0xDB
#elif (SIZEOF_CPUSTACK_T == 2)
- /* 16bit cpustack_t */
+ /* 16bit cpu_stack_t */
#define CONFIG_KERN_STACKFILLCODE 0xA5A5
#define CONFIG_KERN_MEMFILLCODE 0xDBDB
#elif (SIZEOF_CPUSTACK_T == 4)
- /* 32bit cpustack_t */
+ /* 32bit cpu_stack_t */
#define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5UL
#define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBUL
#elif (SIZEOF_CPUSTACK_T == 8)
- /* 64bit cpustack_t */
+ /* 64bit cpu_stack_t */
#define CONFIG_KERN_STACKFILLCODE 0xA5A5A5A5A5A5A5A5ULL
#define CONFIG_KERN_MEMFILLCODE 0xDBDBDBDBDBDBDBDBULL
#else
- #error No cpustack_t size supported!
+ #error No cpu_stack_t size supported!
#endif
#endif
-#endif /* KERN_PROC_H */
+#endif /* KERN_PROC_H */
projects / bertos.git / blobdiff