Changes in src/libcfa/concurrency/kernel.c [4aa2fb2:2ac095d]

File:

• src/libcfa/concurrency/kernel.c (modified) (35 diffs)

src/libcfa/concurrency/kernel.c

@@ -15 +15 @@
 //
 
-#include "startup.h"
-
-//Start and stop routine for the kernel, declared first to make sure they run first
-void kernel_startup(void)  __attribute__(( constructor( STARTUP_PRIORITY_KERNEL ) ));
-void kernel_shutdown(void) __attribute__(( destructor ( STARTUP_PRIORITY_KERNEL ) ));
-
-//Header
-#include "kernel_private.h"
+#include "libhdr.h"
 
 //C Includes
@@ -35 +28 @@
 
 //CFA Includes
-#include "libhdr.h"
+#include "kernel_private.h"
 #include "preemption.h"
+#include "startup.h"
 
 //Private includes
 #define __CFA_INVOKE_PRIVATE__
 #include "invoke.h"
+
+//Start and stop routine for the kernel, declared first to make sure they run first
+void kernel_startup(void)  __attribute__(( constructor( STARTUP_PRIORITY_KERNEL ) ));
+void kernel_shutdown(void) __attribute__(( destructor ( STARTUP_PRIORITY_KERNEL ) ));
 
 //-----------------------------------------------------------------------------
@@ -59 +57 @@
 // Global state
 
-thread_local processor * this_processor;
-
-coroutine_desc * this_coroutine(void) {
-        return this_processor->current_coroutine;
-}
-
-thread_desc * this_thread(void) {
-        return this_processor->current_thread;
-}
+volatile thread_local processor * this_processor;
+volatile thread_local coroutine_desc * this_coroutine;
+volatile thread_local thread_desc * this_thread;
+volatile thread_local unsigned short disable_preempt_count = 1;
 
 //-----------------------------------------------------------------------------
 // Main thread construction
 struct current_stack_info_t {
-        machine_context_t ctx;  
+        machine_context_t ctx;
         unsigned int size;              // size of stack
         void *base;                             // base of stack
@@ -106 +99 @@
 
 void ?{}( coroutine_desc * this, current_stack_info_t * info) {
-        (&this->stack){ info }; 
+        (&this->stack){ info };
         this->name = "Main Thread";
         this->errno_ = 0;
@@ -136 +129 @@
 void ?{}(processor * this, cluster * cltr) {
         this->cltr = cltr;
-        this->current_coroutine = NULL;
-        this->current_thread = NULL;
         (&this->terminated){};
         this->is_terminated = false;
         this->preemption_alarm = NULL;
         this->preemption = default_preemption();
-        this->disable_preempt_count = 1;                //Start with interrupts disabled
         this->pending_preemption = false;
 
@@ -150 +140 @@
 void ?{}(processor * this, cluster * cltr, processorCtx_t * runner) {
         this->cltr = cltr;
-        this->current_coroutine = NULL;
-        this->current_thread = NULL;
         (&this->terminated){};
         this->is_terminated = false;
-        this->disable_preempt_count = 0;
+        this->preemption_alarm = NULL;
+        this->preemption = default_preemption();
         this->pending_preemption = false;
+        this->kernel_thread = pthread_self();
 
         this->runner = runner;
-        LIB_DEBUG_PRINT_SAFE("Kernel : constructing processor context %p\n", runner);
+        LIB_DEBUG_PRINT_SAFE("Kernel : constructing system processor context %p\n", runner);
         runner{ this };
 }
+
+LIB_DEBUG_DO( bool validate( alarm_list_t * this ); )
 
 void ?{}(system_proc_t * this, cluster * cltr, processorCtx_t * runner) {
@@ -168 +160 @@
 
         (&this->proc){ cltr, runner };
+
+        verify( validate( &this->alarms ) );
 }
 
@@ -184 +178 @@
 
 void ^?{}(cluster * this) {
-        
+
 }
 
@@ -203 +197 @@
 
                 thread_desc * readyThread = NULL;
-                for( unsigned int spin_count = 0; ! this->is_terminated; spin_count++ ) 
+                for( unsigned int spin_count = 0; ! this->is_terminated; spin_count++ )
                 {
                         readyThread = nextThread( this->cltr );
@@ -209 +203 @@
                         if(readyThread)
                         {
+                                verify( disable_preempt_count > 0 );
+
                                 runThread(this, readyThread);
+
+                                verify( disable_preempt_count > 0 );
 
                                 //Some actions need to be taken from the kernel
@@ -229 +227 @@
 }
 
-// runThread runs a thread by context switching 
-// from the processor coroutine to the target thread 
+// runThread runs a thread by context switching
+// from the processor coroutine to the target thread
 void runThread(processor * this, thread_desc * dst) {
         coroutine_desc * proc_cor = get_coroutine(this->runner);
         coroutine_desc * thrd_cor = get_coroutine(dst);
-        
+
         //Reset the terminating actions here
         this->finish.action_code = No_Action;
 
         //Update global state
-        this->current_thread = dst;
+        this_thread = dst;
 
         // Context Switch to the thread
@@ -246 +244 @@
 }
 
-// Once a thread has finished running, some of 
+// Once a thread has finished running, some of
 // its final actions must be executed from the kernel
 void finishRunning(processor * this) {
@@ -256 +254 @@
         }
         else if( this->finish.action_code == Release_Schedule ) {
-                unlock( this->finish.lock );            
+                unlock( this->finish.lock );
                 ScheduleThread( this->finish.thrd );
         }
@@ -289 +287 @@
         processor * proc = (processor *) arg;
         this_processor = proc;
+        this_coroutine = NULL;
+        this_thread = NULL;
+        disable_preempt_count = 1;
         // SKULLDUGGERY: We want to create a context for the processor coroutine
         // which is needed for the 2-step context switch. However, there is no reason
-        // to waste the perfectly valid stack create by pthread. 
+        // to waste the perfectly valid stack create by pthread.
         current_stack_info_t info;
         machine_context_t ctx;
@@ -300 +301 @@
 
         //Set global state
-        proc->current_coroutine = &proc->runner->__cor;
-        proc->current_thread = NULL;
+        this_coroutine = &proc->runner->__cor;
+        this_thread = NULL;
 
         //We now have a proper context from which to schedule threads
         LIB_DEBUG_PRINT_SAFE("Kernel : core %p created (%p, %p)\n", proc, proc->runner, &ctx);
 
-        // SKULLDUGGERY: Since the coroutine doesn't have its own stack, we can't 
-        // resume it to start it like it normally would, it will just context switch 
-        // back to here. Instead directly call the main since we already are on the 
+        // SKULLDUGGERY: Since the coroutine doesn't have its own stack, we can't
+        // resume it to start it like it normally would, it will just context switch
+        // back to here. Instead directly call the main since we already are on the
         // appropriate stack.
         proc_cor_storage.__cor.state = Active;
@@ -315 +316 @@
 
         // Main routine of the core returned, the core is now fully terminated
-        LIB_DEBUG_PRINT_SAFE("Kernel : core %p main ended (%p)\n", proc, proc->runner); 
+        LIB_DEBUG_PRINT_SAFE("Kernel : core %p main ended (%p)\n", proc, proc->runner);
 
         return NULL;
@@ -322 +323 @@
 void start(processor * this) {
         LIB_DEBUG_PRINT_SAFE("Kernel : Starting core %p\n", this);
-        
+
+        // SIGALRM must only be caught by the system processor
+        sigset_t old_mask;
+        bool is_system_proc = this_processor == &systemProcessor->proc;
+        if ( is_system_proc ) {
+                // Child kernel-thread inherits the signal mask from the parent kernel-thread. So one special case for the
+                // system processor creating the user processor => toggle the blocking SIGALRM on system processor, create user
+                // processor, and toggle back (below) previous signal mask of the system processor.
+
+                sigset_t new_mask;
+                sigemptyset( &new_mask );
+                sigemptyset( &old_mask );
+                sigaddset( &new_mask, SIGALRM );
+
+                if ( sigprocmask( SIG_BLOCK, &new_mask, &old_mask ) == -1 ) {
+                        abortf( "internal error, sigprocmask" );
+                }
+
+                assert( ! sigismember( &old_mask, SIGALRM ) );
+        }
+
         pthread_create( &this->kernel_thread, NULL, CtxInvokeProcessor, (void*)this );
 
-        LIB_DEBUG_PRINT_SAFE("Kernel : core %p started\n", this);       
+        // Toggle back previous signal mask of system processor.
+        if ( is_system_proc ) {
+                if ( sigprocmask( SIG_SETMASK, &old_mask, NULL ) == -1 ) {
+                        abortf( "internal error, sigprocmask" );
+                } // if
+        } // if
+
+        LIB_DEBUG_PRINT_SAFE("Kernel : core %p started\n", this);
 }
 
@@ -331 +359 @@
 // Scheduler routines
 void ScheduleThread( thread_desc * thrd ) {
-        if( !thrd ) return;
+        // if( !thrd ) return;
+        assert( thrd );
+        assert( thrd->cor.state != Halted );
+
+        verify( disable_preempt_count > 0 );
 
         verifyf( thrd->next == NULL, "Expected null got %p", thrd->next );
-        
-        lock( &systemProcessor->proc.cltr->lock );
+
+        lock( &systemProcessor->proc.cltr->lock DEBUG_CTX2 );
         append( &systemProcessor->proc.cltr->ready_queue, thrd );
         unlock( &systemProcessor->proc.cltr->lock );
+
+        verify( disable_preempt_count > 0 );
 }
 
 thread_desc * nextThread(cluster * this) {
-        lock( &this->lock );
+        verify( disable_preempt_count > 0 );
+        lock( &this->lock DEBUG_CTX2 );
         thread_desc * head = pop_head( &this->ready_queue );
         unlock( &this->lock );
+        verify( disable_preempt_count > 0 );
         return head;
 }
 
-void ScheduleInternal() {
+void BlockInternal() {
+        disable_interrupts();
+        verify( disable_preempt_count > 0 );
         suspend();
-}
-
-void ScheduleInternal( spinlock * lock ) {
+        verify( disable_preempt_count > 0 );
+        enable_interrupts( DEBUG_CTX );
+}
+
+void BlockInternal( spinlock * lock ) {
+        disable_interrupts();
         this_processor->finish.action_code = Release;
         this_processor->finish.lock = lock;
+
+        verify( disable_preempt_count > 0 );
         suspend();
-}
-
-void ScheduleInternal( thread_desc * thrd ) {
+        verify( disable_preempt_count > 0 );
+
+        enable_interrupts( DEBUG_CTX );
+}
+
+void BlockInternal( thread_desc * thrd ) {
+        disable_interrupts();
+        assert( thrd->cor.state != Halted );
         this_processor->finish.action_code = Schedule;
         this_processor->finish.thrd = thrd;
+
+        verify( disable_preempt_count > 0 );
         suspend();
-}
-
-void ScheduleInternal( spinlock * lock, thread_desc * thrd ) {
+        verify( disable_preempt_count > 0 );
+
+        enable_interrupts( DEBUG_CTX );
+}
+
+void BlockInternal( spinlock * lock, thread_desc * thrd ) {
+        disable_interrupts();
         this_processor->finish.action_code = Release_Schedule;
         this_processor->finish.lock = lock;
         this_processor->finish.thrd = thrd;
+
+        verify( disable_preempt_count > 0 );
         suspend();
-}
-
-void ScheduleInternal(spinlock ** locks, unsigned short count) {
+        verify( disable_preempt_count > 0 );
+
+        enable_interrupts( DEBUG_CTX );
+}
+
+void BlockInternal(spinlock ** locks, unsigned short count) {
+        disable_interrupts();
         this_processor->finish.action_code = Release_Multi;
         this_processor->finish.locks = locks;
         this_processor->finish.lock_count = count;
+
+        verify( disable_preempt_count > 0 );
         suspend();
-}
-
-void ScheduleInternal(spinlock ** locks, unsigned short lock_count, thread_desc ** thrds, unsigned short thrd_count) {
+        verify( disable_preempt_count > 0 );
+
+        enable_interrupts( DEBUG_CTX );
+}
+
+void BlockInternal(spinlock ** locks, unsigned short lock_count, thread_desc ** thrds, unsigned short thrd_count) {
+        disable_interrupts();
         this_processor->finish.action_code = Release_Multi_Schedule;
         this_processor->finish.locks = locks;
@@ -383 +449 @@
         this_processor->finish.thrds = thrds;
         this_processor->finish.thrd_count = thrd_count;
+
+        verify( disable_preempt_count > 0 );
         suspend();
+        verify( disable_preempt_count > 0 );
+
+        enable_interrupts( DEBUG_CTX );
 }
 
@@ -392 +463 @@
 // Kernel boot procedures
 void kernel_startup(void) {
-        LIB_DEBUG_PRINT_SAFE("Kernel : Starting\n");    
+        LIB_DEBUG_PRINT_SAFE("Kernel : Starting\n");
 
         // Start by initializing the main thread
-        // SKULLDUGGERY: the mainThread steals the process main thread 
+        // SKULLDUGGERY: the mainThread steals the process main thread
         // which will then be scheduled by the systemProcessor normally
         mainThread = (thread_desc *)&mainThread_storage;
@@ -403 +474 @@
         LIB_DEBUG_PRINT_SAFE("Kernel : Main thread ready\n");
 
-        // Enable preemption
-        kernel_start_preemption();
-
         // Initialize the system cluster
         systemCluster = (cluster *)&systemCluster_storage;
@@ -417 +485 @@
         systemProcessor{ systemCluster, (processorCtx_t *)&systemProcessorCtx_storage };
 
-        // Add the main thread to the ready queue 
+        // Add the main thread to the ready queue
         // once resume is called on systemProcessor->runner the mainThread needs to be scheduled like any normal thread
         ScheduleThread(mainThread);
@@ -423 +491 @@
         //initialize the global state variables
         this_processor = &systemProcessor->proc;
-        this_processor->current_thread = mainThread;
-        this_processor->current_coroutine = &mainThread->cor;
+        this_thread = mainThread;
+        this_coroutine = &mainThread->cor;
+        disable_preempt_count = 1;
+
+        // Enable preemption
+        kernel_start_preemption();
 
         // SKULLDUGGERY: Force a context switch to the system processor to set the main thread's context to the current UNIX
         // context. Hence, the main thread does not begin through CtxInvokeThread, like all other threads. The trick here is that
-        // mainThread is on the ready queue when this call is made. 
+        // mainThread is on the ready queue when this call is made.
         resume( systemProcessor->proc.runner );
 
@@ -435 +507 @@
         // THE SYSTEM IS NOW COMPLETELY RUNNING
         LIB_DEBUG_PRINT_SAFE("Kernel : Started\n--------------------------------------------------\n\n");
+
+        enable_interrupts( DEBUG_CTX );
 }
 
 void kernel_shutdown(void) {
         LIB_DEBUG_PRINT_SAFE("\n--------------------------------------------------\nKernel : Shutting down\n");
+
+        disable_interrupts();
 
         // SKULLDUGGERY: Notify the systemProcessor it needs to terminates.
@@ -448 +524 @@
         // THE SYSTEM IS NOW COMPLETELY STOPPED
 
+        // Disable preemption
+        kernel_stop_preemption();
+
         // Destroy the system processor and its context in reverse order of construction
         // These were manually constructed so we need manually destroy them
@@ -457 +536 @@
         ^(mainThread){};
 
-        LIB_DEBUG_PRINT_SAFE("Kernel : Shutdown complete\n");   
+        LIB_DEBUG_PRINT_SAFE("Kernel : Shutdown complete\n");
 }
 
@@ -467 +546 @@
         // abort cannot be recursively entered by the same or different processors because all signal handlers return when
         // the globalAbort flag is true.
-        lock( &kernel_abort_lock );
+        lock( &kernel_abort_lock DEBUG_CTX2 );
 
         // first task to abort ?
@@ -473 +552 @@
                 kernel_abort_called = true;
                 unlock( &kernel_abort_lock );
-        } 
+        }
         else {
                 unlock( &kernel_abort_lock );
-                
+
                 sigset_t mask;
                 sigemptyset( &mask );
@@ -482 +561 @@
                 sigaddset( &mask, SIGUSR1 );                    // block SIGUSR1 signals
                 sigsuspend( &mask );                            // block the processor to prevent further damage during abort
-                _exit( EXIT_FAILURE );                          // if processor unblocks before it is killed, terminate it              
-        }
-
-        return this_thread();
+                _exit( EXIT_FAILURE );                          // if processor unblocks before it is killed, terminate it
+        }
+
+        return this_thread;
 }
 
@@ -494 +573 @@
         __lib_debug_write( STDERR_FILENO, abort_text, len );
 
-        if ( thrd != this_coroutine() ) {
-                len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", this_coroutine()->name, this_coroutine() );
+        if ( thrd != this_coroutine ) {
+                len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", this_coroutine->name, this_coroutine );
                 __lib_debug_write( STDERR_FILENO, abort_text, len );
-        } 
+        }
         else {
                 __lib_debug_write( STDERR_FILENO, ".\n", 2 );
@@ -505 +584 @@
 extern "C" {
         void __lib_debug_acquire() {
-                lock(&kernel_debug_lock);
+                lock( &kernel_debug_lock DEBUG_CTX2 );
         }
 
         void __lib_debug_release() {
-                unlock(&kernel_debug_lock);
+                unlock( &kernel_debug_lock );
         }
 }
@@ -525 +604 @@
 }
 
-bool try_lock( spinlock * this ) {
-        return this->lock == 0 && __sync_lock_test_and_set_4( &this->lock, 1 ) == 0;
-}
-
-void lock( spinlock * this ) {
+bool try_lock( spinlock * this DEBUG_CTX_PARAM2 ) {
+        bool ret = this->lock == 0 && __sync_lock_test_and_set_4( &this->lock, 1 ) == 0;
+        LIB_DEBUG_DO( this->prev = caller; )
+        return ret;
+}
+
+void lock( spinlock * this DEBUG_CTX_PARAM2 ) {
         for ( unsigned int i = 1;; i += 1 ) {
                 if ( this->lock == 0 && __sync_lock_test_and_set_4( &this->lock, 1 ) == 0 ) break;
         }
+        LIB_DEBUG_DO( this->prev = caller; )
 }
 
@@ -547 +629 @@
 
 void wait( signal_once * this ) {
-        lock( &this->lock );
+        lock( &this->lock DEBUG_CTX2 );
         if( !this->cond ) {
-                append( &this->blocked, this_thread() );
-                ScheduleInternal( &this->lock );
-                lock( &this->lock );
-        }
-        unlock( &this->lock );
+                append( &this->blocked, (thread_desc*)this_thread );
+                BlockInternal( &this->lock );
+        }
+        else {
+                unlock( &this->lock );
+        }
 }
 
 void signal( signal_once * this ) {
-        lock( &this->lock );
+        lock( &this->lock DEBUG_CTX2 );
         {
                 this->cond = true;
 
+                disable_interrupts();
                 thread_desc * it;
                 while( it = pop_head( &this->blocked) ) {
                         ScheduleThread( it );
                 }
+                enable_interrupts( DEBUG_CTX );
         }
         unlock( &this->lock );
@@ -590 +675 @@
                 }
                 head->next = NULL;
-        }       
+        }
         return head;
 }
@@ -609 +694 @@
                 this->top = top->next;
                 top->next = NULL;
-        }       
+        }
         return top;
 }