X-Git-Url: https://codewiz.org/gitweb?a=blobdiff_plain;f=bertos%2Fkern%2Fproc.h;h=efbdf458fb6ed5c0db5ca50e829af970d7042512;hb=0c71afa65077b10d069192c1d36c0df1440e1b97;hp=f8de758ffeec511879400f20d750311d3b3c992b;hpb=2670d520a86faa8372952207fed4ef097ff2e726;p=bertos.git diff --git a/bertos/kern/proc.h b/bertos/kern/proc.h index f8de758f..efbdf458 100644 --- a/bertos/kern/proc.h +++ b/bertos/kern/proc.h @@ -30,22 +30,30 @@ * Copyright 1999, 2000, 2001, 2008 Bernie Innocenti * --> * - * \brief Process scheduler (public interface). + * \brief BeRTOS Kernel core (Process scheduler). * * \version $Id$ * \author Bernie Innocenti + * + * $WIZ$ module_name = "kernel" + * $WIZ$ module_configuration = "bertos/cfg/cfg_proc.h" + * $WIZ$ module_depends = "switch_ctx", "coop" + * $WIZ$ module_supports = "not atmega103" */ + #ifndef KERN_PROC_H #define KERN_PROC_H -#include "cfg/cfg_kern.h" +#include "cfg/cfg_proc.h" +#include "cfg/cfg_monitor.h" + #include #if CONFIG_KERN_PREEMPT #include // ASSERT() #endif -#include // cpustack_t +#include // cpu_stack_t #include // CPU_SAVED_REGS_CNT /* @@ -54,9 +62,29 @@ */ struct Process; -/* Task scheduling services */ +/** + * Initialize the process subsystem (kernel). + * It must be called before using any process related function. + */ 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); + +/** + * Create a new named process and schedules it for execution. + * + * \note The function + * \code + * proc_new(entry, data, stacksize, stack) + * \endcode + * is a more convenient way to create a process, as you don't have to specify + * the name. + * + * \param name Name of the process (currently unused). + * \param entry Function that the process will execute. + * \param data Pointer to user data. + * \param stacksize Length of the stack. + * \param stack Pointer to the memory area to be used as a 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)) @@ -64,18 +92,51 @@ struct Process *proc_new_with_name(const char* name, void (*entry)(void), iptr_t #define proc_new(entry,data,size,stack) proc_new_with_name(#entry,(entry),(data),(size),(stack)) #endif +/** + * Terminate the execution of the current process. + */ void proc_exit(void); + +/** + * Co-operative context switch. + * + * The process that calls this function will release the CPU before its cpu quantum + * expires, the scheduler will run to select the next process that will take control + * of the processor. + * \note This function is available only if CONFIG_KERN is enabled + * \sa cpu_relax(), which is the recommended method to release the cpu. + */ void proc_yield(void); +void proc_rename(struct Process *proc, const char *name); +const char *proc_name(struct Process *proc); +const char *proc_currentName(void); + +/** + * Return a pointer to the user data of the current process. + * + * To obtain user data, just call this function inside the process. Remember to cast + * the returned pointer to the correct type. + * \return Pointer to the user data of the current process. + */ +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_currentUserData(void); -void proc_rename(struct Process *proc, const char *name); -const char *proc_name(struct Process *proc); -const char *proc_currentName(void); +/** + * 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_PRI void proc_setPri(struct Process *proc, int pri); @@ -85,9 +146,6 @@ const char *proc_currentName(void); } #endif -/** Global preemption disable nesting counter. */ -extern int preempt_forbid_cnt; - /** * Disable preemptive task switching. * @@ -98,6 +156,9 @@ extern int preempt_forbid_cnt; * \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 @@ -108,11 +169,34 @@ extern int preempt_forbid_cnt; INLINE void proc_forbid(void) { #if CONFIG_KERN_PREEMPT - // No need to protect against interrupts here. - ++preempt_forbid_cnt; + 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 + * Make sure _preempt_forbid_cnt is flushed to memory so the * preemption softirq will see the correct value from now on. */ MEMORY_BARRIER; @@ -133,13 +217,13 @@ INLINE void proc_permit(void) * 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. */ - --preempt_forbid_cnt; - ASSERT(preempt_forbid_cnt >= 0); + ASSERT(_preempt_forbid_cnt != 0); + --_preempt_forbid_cnt; /* - * This ensures preempt_forbid_cnt is flushed to memory immediately + * This ensures _preempt_forbid_cnt is flushed to memory immediately * so the preemption interrupt sees the correct value. */ MEMORY_BARRIER; @@ -147,6 +231,21 @@ INLINE void proc_permit(void) #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. */ @@ -171,10 +270,10 @@ INLINE void proc_permit(void) * stack. * * The actual size computed by the default formula is: - * AVR: 102 - * i386: 156 - * ARM: 164 - * x86_64: 184 + * \li AVR: 102 + * \li i386: 156 + * \li ARM: 164 + * \li x86_64: 184 * * Note that on most 16bit architectures, interrupts will also * run on the stack of the currently running process. Nested @@ -183,8 +282,8 @@ INLINE void proc_permit(void) * usage. */ #define CONFIG_KERN_MINSTACKSIZE \ - (CPU_SAVED_REGS_CNT * 2 * sizeof(cpustack_t) \ - + 32 * sizeof(int)) + (CPU_SAVED_REGS_CNT * 2 * sizeof(cpu_stack_t) \ + + 48 * sizeof(int)) #endif #endif @@ -192,23 +291,23 @@ INLINE void proc_permit(void) #if CONFIG_KERN_MONITOR #include #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