X-Git-Url: https://codewiz.org/gitweb?a=blobdiff_plain;f=kern%2Fproc.c;h=5290c2c5129d6095cf2d9a0aca2a9ce192123b1c;hb=09f84dd1e880b343be5225b4f87867eb823fe818;hp=613cf58d73b1d2490f5c39b3a448caee52c23421;hpb=a784017154df4320114e044c4b7eda76ea0a2a9a;p=bertos.git diff --git a/kern/proc.c b/kern/proc.c old mode 100755 new mode 100644 index 613cf58d..5290c2c5 --- a/kern/proc.c +++ b/kern/proc.c @@ -1,9 +1,34 @@ -/*! +/** * \file * * * \brief Simple realtime multitasking scheduler. @@ -15,36 +40,28 @@ * \author Stefano Fedrigo */ -/* - * $Log$ - * Revision 1.5 2004/07/14 14:18:09 rasky - * Merge da SC: Rimosso timer dentro il task, che è uno spreco di memoria per troppi task - * - * Revision 1.4 2004/07/13 19:21:28 aleph - * Avoid warning for unused arg when compiled without some CONFIG_KERN_xx options - * - * Revision 1.3 2004/06/06 18:37:57 bernie - * Rename event macros to look like regular functions. - * - * Revision 1.2 2004/06/03 11:27:09 bernie - * Add dual-license information. - * - * Revision 1.1 2004/05/23 17:27:00 bernie - * Import kern/ subdirectory. - * - */ -#include "cpu.h" #include "proc_p.h" #include "proc.h" -#include "event.h" -#include "hw.h" -#include +//#include "hw.h" +#include +#include +#include +#include +#include +#include +#include /* ARCH_EMUL */ +#include /* ABS() */ #include /* memset() */ -/* CPU dependent context switching routines */ -extern void asm_switch_context(cpustack_t **new_sp, cpustack_t **save_sp); +/** + * CPU dependent context switching routines. + * + * \note This function *MUST* preserve also the status of the interrupts. + */ +EXTERN_C void asm_switch_context(cpustack_t **new_sp, cpustack_t **save_sp); +EXTERN_C int asm_switch_version(void); /* * The scheduer tracks ready and waiting processes @@ -56,6 +73,7 @@ extern void asm_switch_context(cpustack_t **new_sp, cpustack_t **save_sp); REGISTER Process *CurrentProcess; REGISTER List ProcReadyList; + #if CONFIG_KERN_PREEMPTIVE /* * The time sharing scheduler forces a task switch when @@ -70,42 +88,58 @@ uint16_t Quantum; extern List StackFreeList; #endif -/* The main process (the one that executes main()) */ +/** The main process (the one that executes main()). */ struct Process MainProcess; -static void proc_init_struct(Process* proc) + +static void proc_init_struct(Process *proc) { - /* Avoid warning for unused argument */ + /* Avoid warning for unused argument. */ (void)proc; #if CONFIG_KERN_SIGNALS proc->sig_recv = 0; #endif +#if CONFIG_KERN_PREEMPTIVE + proc->forbid_cnt = 0; +#endif + #if CONFIG_KERN_HEAP proc->flags = 0; #endif } +MOD_DEFINE(proc); + void proc_init(void) { - INITLIST(&ProcReadyList); + LIST_INIT(&ProcReadyList); + +#if CONFIG_KERN_MONITOR + monitor_init(); +#endif /* We "promote" the current context into a real process. The only thing we have - to do is create a PCB and make it current. We don't need to setup the stack - pointer because it will be written the first time we switch to another process. */ + * to do is create a PCB and make it current. We don't need to setup the stack + * pointer because it will be written the first time we switch to another process. + */ proc_init_struct(&MainProcess); CurrentProcess = &MainProcess; + + /* Make sure the assembly routine is up-to-date with us */ + ASSERT(asm_switch_version() == 1); + MOD_INIT(proc); } -/*! +/** * Create a new process, starting at the provided entry point. * * \return Process structure of new created process * if successful, NULL otherwise. */ -Process *proc_new(void (*entry)(void), size_t stacksize, cpustack_t *stack_base) +struct Process *proc_new_with_name(UNUSED(const char *, name), void (*entry)(void), iptr_t data, size_t stacksize, cpustack_t *stack_base) { Process *proc; size_t i; @@ -115,19 +149,17 @@ Process *proc_new(void (*entry)(void), size_t stacksize, cpustack_t *stack_base) #endif #if (ARCH & ARCH_EMUL) - /* Ignore stack provided by caller - * and use the large enough default instead - */ - stack_base = (cpustack_t *)StackFreeList.head; - REMOVE((Node *)stack_base); - stacksize = DEF_STACKSIZE; + /* Ignore stack provided by caller and use the large enough default instead. */ + stack_base = (cpustack_t *)LIST_HEAD(&StackFreeList); + REMOVE(LIST_HEAD(&StackFreeList)); + stacksize = CONFIG_PROC_DEFSTACKSIZE; #elif CONFIG_KERN_HEAP /* Did the caller provide a stack for us? */ if (!stack_base) { /* Did the caller specify the desired stack size? */ if (!stacksize) - stacksize = CONFIG_KERN_DEFSTACKSIZE + sizeof(Process); + stacksize = CONFIG_PROC_DEFSTACKSIZE + sizeof(Process); /* Allocate stack dinamically */ if (!(stack_base = heap_alloc(stacksize))) @@ -141,10 +173,10 @@ Process *proc_new(void (*entry)(void), size_t stacksize, cpustack_t *stack_base) ASSERT(stacksize); #endif -#ifdef _DEBUG +#if CONFIG_KERN_MONITOR /* Fill-in the stack with a special marker to help debugging */ memset(stack_base, CONFIG_KERN_STACKFILLCODE, stacksize / sizeof(cpustack_t)); -#endif /* _DEBUG */ +#endif /* Initialize the process control block */ if (CPU_STACK_GROWS_UPWARD) @@ -163,6 +195,7 @@ Process *proc_new(void (*entry)(void), size_t stacksize, cpustack_t *stack_base) } proc_init_struct(proc); + proc->user_data = data; #if CONFIG_KERN_HEAP proc->stack_base = stack_base; @@ -180,15 +213,27 @@ Process *proc_new(void (*entry)(void), size_t stacksize, cpustack_t *stack_base) CPU_PUSH_WORD(proc->stack, CPU_REG_INIT_VALUE(i)); /* Add to ready list */ - DISABLE_INTS; - SCHED_ENQUEUE(proc); - ENABLE_INTS; + ATOMIC(SCHED_ENQUEUE(proc)); + +#if CONFIG_KERN_MONITOR + monitor_add(proc, name, stack_base, stacksize); +#endif return proc; } +/** Rename a process */ +void proc_rename(struct Process *proc, const char *name) +{ +#if CONFIG_KERN_MONITOR + monitor_rename(proc, name); +#else + (void)proc; (void)name; +#endif +} + -/*! +/** * System scheduler: pass CPU control to the next process in * the ready queue. * @@ -198,41 +243,50 @@ Process *proc_new(void (*entry)(void), size_t stacksize, cpustack_t *stack_base) */ void proc_schedule(void) { - /* This function must not have any "auto" variables, otherwise - * the compiler might put them on the stack of the process - * being switched out. - */ - static Process *old_process; + struct Process *old_process; + cpuflags_t flags; /* Remember old process to save its context later */ old_process = CurrentProcess; - CurrentProcess = NULL; - /* Poll on the ready queue for the first ready process - */ - for(;;) /* forever */ +#ifdef IRQ_RUNNING + /* Scheduling in interrupts is a nono. */ + ASSERT(!IRQ_RUNNING()); +#endif + + /* Poll on the ready queue for the first ready process */ + IRQ_SAVE_DISABLE(flags); + while (!(CurrentProcess = (struct Process *)list_remHead(&ProcReadyList))) { - /* Do CPU specific idle processing (ARGH, should be moved to the end of the loop!) */ - SCHEDULER_IDLE; - - DISABLE_INTS; - if (!ISLISTEMPTY(&ProcReadyList)) - { - /* Get process from ready list */ - CurrentProcess = (Process *)ProcReadyList.head; - REMOVE((Node *)CurrentProcess); - ENABLE_INTS; - break; - } - ENABLE_INTS; + /* + * Make sure we physically reenable interrupts here, no matter what + * the current task status is. This is important because if we + * are idle-spinning, we must allow interrupts, otherwise no + * process will ever wake up. + * + * During idle-spinning, can occur an interrupt, it may be able to + * modify \p ProcReadyList. To ensure that compiler reload this + * variable every while cycle we call CPU_MEMORY_BARRIER. + * The memory barrier ensure that all variables used in this context + * are reloaded. + * \todo If there was a way to write sig_wait() so that it does not + * disable interrupts while waiting, there would not be any + * reason to do this. + */ + IRQ_ENABLE; + CPU_IDLE; + CPU_MEMORY_BARRIER; + IRQ_DISABLE; } + IRQ_RESTORE(flags); - /* Optimization: don't switch contexts when the active + /* + * Optimization: don't switch contexts when the active * process has not changed. */ if (CurrentProcess != old_process) { - static cpustack_t* dummy; + cpustack_t *dummy; #if CONFIG_KERN_PREEMPTIVE /* Reset quantum for this process */ @@ -253,13 +307,18 @@ void proc_schedule(void) } -/*! +/** * Terminate the current process */ void proc_exit(void) { +#if CONFIG_KERN_MONITOR + monitor_remove(CurrentProcess); +#endif + #if CONFIG_KERN_HEAP - /* The following code is BROKEN. + /* + * The following code is BROKEN. * We are freeing our own stack before entering proc_schedule() * BAJO: A correct fix would be to rearrange the scheduler with * an additional parameter which frees the old stack/process @@ -271,12 +330,13 @@ void proc_exit(void) #endif #if (ARCH & ARCH_EMUL) -#error This is wrong +#warning This is wrong /* Reinsert process stack in free list */ ADDHEAD(&StackFreeList, (Node *)(CurrentProcess->stack - - (DEF_STACKSIZE / sizeof(cpustack_t)))); + - (CONFIG_PROC_DEFSTACKSIZE / sizeof(cpustack_t)))); - /* NOTE: At this point the first two words of what used + /* + * NOTE: At this point the first two words of what used * to be our stack contain a list node. From now on, we * rely on the compiler not reading/writing the stack. */ @@ -288,19 +348,22 @@ void proc_exit(void) } -/*! +/** * Co-operative context switch */ void proc_switch(void) { - DISABLE_INTS; + cpuflags_t flags; + + IRQ_SAVE_DISABLE(flags); SCHED_ENQUEUE(CurrentProcess); - ENABLE_INTS; + IRQ_RESTORE(flags); + proc_schedule(); } -/*! +/** * Get the pointer to the current process */ struct Process *proc_current(void) @@ -308,59 +371,46 @@ struct Process *proc_current(void) return CurrentProcess; } - -#if 0 /* Simple testcase for the scheduler */ - -/*! - * Proc scheduling test subthread 1 +/** + * Get the pointer to the user data of the current process */ -static void NORETURN proc_test_thread1(void) +iptr_t proc_current_user_data(void) { - for (;;) - { - kputs(">task 1\n"); - timer_delay(50); - proc_switch(); - } + return CurrentProcess->user_data; } -/*! - * Proc scheduling test subthread 2 + +#if CONFIG_KERN_PREEMPTIVE + +/** + * Disable preemptive task switching. + * + * The scheduler maintains a per-process 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(). + * + * Calling functions that could sleep while task switching is disabled + * is dangerous, although supported. Preemptive task switching is + * resumed while the process is sleeping and disabled again as soon as + * it wakes up again. + * + * \sa proc_permit() */ -static void NORETURN proc_test_thread2(void) +void proc_forbid(void) { - for (;;) - { - kputs(">task 2\n"); - timer_delay(75); - proc_switch(); - } + /* No need to protect against interrupts here. */ + ++CurrentProcess->forbid_cnt; } -static cpustack_t proc_test_stack1[CONFIG_KERN_DEFSTACKSIZE/sizeof(cpustack_t)]; -static cpustack_t proc_test_stack2[CONFIG_KERN_DEFSTACKSIZE/sizeof(cpustack_t)]; - -/*! - * Proc scheduling test +/** + * Re-enable preemptive task switching. + * + * \sa proc_forbid() */ -void NORETURN proc_test(void) +void proc_permit(void) { - proc_new(proc_test_thread1, sizeof(proc_test_stack1), proc_test_stack1); - proc_new(proc_test_thread2, sizeof(proc_test_stack2), proc_test_stack2); - kputs("Created tasks\n"); - - kputs("stack1:\n"); - kdump(proc_test_stack1+sizeof(proc_test_stack1)-64, 64); - kputs("stack2:\n"); - kdump(proc_test_stack2+sizeof(proc_test_stack1)-64, 64); - - for (;;) - { - kputs(">main task\n"); - timer_delay(93); - proc_switch(); - } - - ASSERT(false); + /* No need to protect against interrupts here. */ + --CurrentProcess->forbid_cnt; } -#endif + +#endif /* CONFIG_KERN_PREEMPTIVE */