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Kernel: Clean up around Scheduler::yield() a bit.

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Also add assertion in Lock that the scheduler isn't currently active.
I've been seeing occasional fuckups that I suspect might be someone called
by the scheduler trying to take a busy lock.
This commit is contained in:
Andreas Kling 2019-02-06 15:05:47 +01:00
parent 27263b6172
commit 8cc6e304ca
4 changed files with 23 additions and 28 deletions
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33
Kernel/Scheduler.cpp
View file

@ -3,6 +3,7 @@
#include "system.h"
#include "RTC.h"
#include "i8253.h"
#include <AK/TemporaryChange.h>
//#define LOG_EVERY_CONTEXT_SWITCH
//#define SCHEDULER_DEBUG
@ -12,17 +13,27 @@ static const dword time_slice = 5; // *10 = 50ms
Process* current;
Process* g_last_fpu_process;
static Process* s_colonel_process;
static volatile bool s_in_yield;
struct TaskRedirectionData {
word selector;
TSS32 tss;
};
static TaskRedirectionData s_redirection;
static bool s_active;
bool Scheduler::is_active()
{
return s_active;
}
bool Scheduler::pick_next()
{
ASSERT_INTERRUPTS_DISABLED();
ASSERT(!s_active);
TemporaryChange<bool> change(s_active, true);
ASSERT(s_active);
if (!current) {
// XXX: The first ever context_switch() goes to the idle process.
@ -176,22 +187,12 @@ bool Scheduler::pick_next()
bool Scheduler::yield()
{
InterruptDisabler disabler;
ASSERT(!s_in_yield);
s_in_yield = true;
if (!current) {
kprintf("PANIC: sched_yield() with !current");
HANG;
}
ASSERT(current);
//dbgprintf("%s<%u> yield()\n", current->name().characters(), current->pid());
if (!pick_next()) {
s_in_yield = false;
if (!pick_next())
return 1;
}
s_in_yield = false;
//dbgprintf("yield() jumping to new process: %x (%s)\n", current->far_ptr().selector, current->name().characters());
switch_now();
return 0;
@ -269,11 +270,6 @@ bool Scheduler::context_switch(Process& process)
return true;
}
int sched_yield()
{
return Scheduler::yield();
}
static void initialize_redirection()
{
auto& descriptor = get_gdt_entry(s_redirection.selector);
@ -319,7 +315,6 @@ void Scheduler::initialize()
s_colonel_process = Process::create_kernel_process("colonel", nullptr);
current = nullptr;
g_last_fpu_process = nullptr;
s_in_yield = false;
load_task_register(s_redirection.selector);
}