Changes in src/libcfa/concurrency/preemption.c [c5ac6d5:0b33412]

File:

• src/libcfa/concurrency/preemption.c (modified) (10 diffs)

src/libcfa/concurrency/preemption.c

@@ -17 +17 @@
 #include "preemption.h"
 
+
 extern "C" {
+#include <errno.h>
+#define __USE_GNU
 #include <signal.h>
-}
-
-#define __CFA_DEFAULT_PREEMPTION__ 10
+#undef __USE_GNU
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+}
+
+#include "libhdr.h"
+
+#define __CFA_DEFAULT_PREEMPTION__ 10000
 
 __attribute__((weak)) unsigned int default_preemption() {
@@ -27 +36 @@
 }
 
+#define __CFA_SIGCXT__ ucontext_t *
+#define __CFA_SIGPARMS__ __attribute__((unused)) int sig, __attribute__((unused)) siginfo_t *sfp, __attribute__((unused)) __CFA_SIGCXT__ cxt
+
 static void preempt( processor   * this );
 static void timeout( thread_desc * this );
+
+void sigHandler_ctxSwitch( __CFA_SIGPARMS__ );
+void sigHandler_alarm    ( __CFA_SIGPARMS__ );
+
+static void __kernel_sigaction( int sig, void (*handler)(__CFA_SIGPARMS__), int flags );
 
 //=============================================================================================
@@ -35 +52 @@
 
 void kernel_start_preemption() {
-
-}
+        LIB_DEBUG_PRINT_SAFE("Kernel : Starting preemption\n");
+        __kernel_sigaction( SIGUSR1, sigHandler_ctxSwitch, SA_SIGINFO );
+        __kernel_sigaction( SIGALRM, sigHandler_alarm    , SA_SIGINFO );
+}
+
+void kernel_stop_preemption() {
+        //Block all signals, we are no longer in a position to handle them
+        sigset_t mask;
+        sigfillset( &mask );
+        sigprocmask( SIG_BLOCK, &mask, NULL );
+        LIB_DEBUG_PRINT_SAFE("Kernel : Preemption stopped\n");
+
+        assert( !systemProcessor->alarms.head );
+        assert( systemProcessor->alarms.tail == &systemProcessor->alarms.head );
+}
+
+LIB_DEBUG_DO( bool validate( alarm_list_t * this ); )
 
 void tick_preemption() {
+        LIB_DEBUG_DO(
+                char text[256];
+                __attribute__((unused)) int len = snprintf( text, 256, "Ticking preemption\n" );
+                LIB_DEBUG_WRITE( STDERR_FILENO, text, len );
+        );
+
         alarm_list_t * alarms = &systemProcessor->alarms;
         __cfa_time_t currtime = __kernel_get_time();
         while( alarms->head && alarms->head->alarm < currtime ) {
                 alarm_node_t * node = pop(alarms);
+                LIB_DEBUG_DO(
+                        len = snprintf( text, 256, "Ticking %p\n", node );
+                        LIB_DEBUG_WRITE( STDERR_FILENO, text, len );
+                );
                 if( node->kernel_alarm ) {
                         preempt( node->proc );
@@ -50 +92 @@
                 }
 
+                LIB_DEBUG_DO( assert( validate( alarms ) ) );
+
                 if( node->period > 0 ) {
-                        node->alarm += node->period;
+                        node->alarm = currtime + node->period;
                         insert( alarms, node );
                 }
@@ -62 +106 @@
                 __kernel_set_timer( alarms->head->alarm - currtime );
         }
+
+        verify( validate( alarms ) );
+        LIB_DEBUG_DO(
+                len = snprintf( text, 256, "Ticking preemption done\n" );
+                LIB_DEBUG_WRITE( STDERR_FILENO, text, len );
+        );
 }
 
 void update_preemption( processor * this, __cfa_time_t duration ) {
-        //     assert( THREAD_GETMEM( disableInt ) && THREAD_GETMEM( disableIntCnt ) == 1 );
+        LIB_DEBUG_DO(
+                char text[256];
+                __attribute__((unused)) int len = snprintf( text, 256, "Processor : %p updating preemption to %lu\n", this, duration );
+                LIB_DEBUG_WRITE( STDERR_FILENO, text, len );
+        );
+
         alarm_node_t * alarm = this->preemption_alarm;
+        duration *= 1000;
 
         // Alarms need to be enabled
@@ -97 +153 @@
 
 void ^?{}( preemption_scope * this ) {
+        disable_interrupts();
+
         update_preemption( this->proc, 0 );
 }
@@ -104 +162 @@
 //=============================================================================================
 
+extern "C" {
+        void disable_interrupts() {
+                __attribute__((unused)) unsigned short new_val = __atomic_add_fetch_2( &disable_preempt_count, 1, __ATOMIC_SEQ_CST );
+                verify( new_val < (unsigned short)65_000 );
+                verify( new_val != (unsigned short) 0 );
+        }
+
+        void enable_interrupts_noRF() {
+                unsigned short prev = __atomic_fetch_add_2( &disable_preempt_count, -1, __ATOMIC_SEQ_CST );
+                verify( prev != (unsigned short) 0 );
+        }
+
+        void enable_interrupts( const char * func ) {
+                unsigned short prev = __atomic_fetch_add_2( &disable_preempt_count, -1, __ATOMIC_SEQ_CST );
+                verify( prev != (unsigned short) 0 );
+                if( prev == 1 && this_processor->pending_preemption ) {
+                        this_processor->pending_preemption = false;
+                        LIB_DEBUG_DO(
+                                char text[256];
+                                __attribute__((unused)) int len = snprintf( text, 256, "Executing deferred CtxSwitch on %p\n", this_processor );
+                                LIB_DEBUG_WRITE( STDERR_FILENO, text, len );
+                        );
+                        BlockInternal( this_processor->current_thread );
+                }
+
+                this_processor->last_enable = func;
+        }
+}
+
+static inline void signal_unblock( bool alarm ) {
+        sigset_t mask;
+        sigemptyset( &mask );
+        sigaddset( &mask, SIGUSR1 );
+
+        if( alarm ) sigaddset( &mask, SIGALRM );
+
+        if ( sigprocmask( SIG_UNBLOCK, &mask, NULL ) == -1 ) {
+            abortf( "internal error, sigprocmask" );
+        } // if
+}
+
 static inline bool preemption_ready() {
-        return this_processor->disable_preempt_count == 0;
+        return disable_preempt_count == 0;
 }
 
@@ -116 +215 @@
 }
 
-void sigHandler_ctxSwitch( __attribute__((unused)) int sig ) {
+void sigHandler_ctxSwitch( __CFA_SIGPARMS__ ) {
+
+        LIB_DEBUG_DO(
+                char text[256];
+                __attribute__((unused)) int len = snprintf( text, 256, "Ctx Switch IRH %p\n", (void *)(cxt->uc_mcontext.gregs[REG_RIP]));
+                LIB_DEBUG_WRITE( STDERR_FILENO, text, len );
+        );
+
+        signal_unblock( false );
         if( preemption_ready() ) {
-                ScheduleInternal( this_processor->current_thread );
+                LIB_DEBUG_DO(
+                        len = snprintf( text, 256, "Ctx Switch IRH : Blocking thread %p on %p\n", this_processor->current_thread, this_processor );
+                        LIB_DEBUG_WRITE( STDERR_FILENO, text, len );
+                );
+                BlockInternal( this_processor->current_thread );
         }
         else {
+                LIB_DEBUG_DO(
+                        len = snprintf( text, 256, "Ctx Switch IRH : Defering\n" );
+                        LIB_DEBUG_WRITE( STDERR_FILENO, text, len );
+                );
                 defer_ctxSwitch();
         }
 }
 
-void sigHandler_alarm( __attribute__((unused)) int sig ) {
+void sigHandler_alarm( __CFA_SIGPARMS__ ) {
+
+        LIB_DEBUG_DO(
+                char text[256];
+                __attribute__((unused)) int len = snprintf( text, 256, "\nAlarm IRH %p\n", (void *)(cxt->uc_mcontext.gregs[REG_RIP]) );
+                LIB_DEBUG_WRITE( STDERR_FILENO, text, len );
+        );
+
+        signal_unblock( true );
         if( try_lock( &systemProcessor->alarm_lock ) ) {
                 tick_preemption();
@@ -133 +256 @@
                 defer_alarm();
         }
+
+        if( preemption_ready() && this_processor->pending_preemption ) {
+                LIB_DEBUG_DO(
+                        len = snprintf( text, 256, "Alarm IRH : Blocking thread\n" );
+                        LIB_DEBUG_WRITE( STDERR_FILENO, text, len );
+                );
+                this_processor->pending_preemption = false;
+                BlockInternal( this_processor->current_thread );
+        }
 }
 
 static void preempt( processor * this ) {
-        pthread_kill( this->kernel_thread, SIGUSR1 );
+        LIB_DEBUG_DO(
+                char text[256];
+                __attribute__((unused)) int len = snprintf( text, 256, "Processor : signalling %p\n", this );
+                LIB_DEBUG_WRITE( STDERR_FILENO, text, len );
+        );
+
+        if( this != systemProcessor ) {
+                pthread_kill( this->kernel_thread, SIGUSR1 );
+        }
+        else {
+                defer_ctxSwitch();
+        }
 }
 
@@ -142 +285 @@
         //TODO : implement waking threads
 }
+
+static void __kernel_sigaction( int sig, void (*handler)(__CFA_SIGPARMS__), int flags ) {
+        struct sigaction act;
+
+        act.sa_sigaction = (void (*)(int, siginfo_t *, void *))handler;
+        sigemptyset( &act.sa_mask );
+        sigaddset( &act.sa_mask, SIGALRM );             // disabled during signal handler
+        sigaddset( &act.sa_mask, SIGUSR1 );
+
+        act.sa_flags = flags;
+
+        if ( sigaction( sig, &act, NULL ) == -1 ) {
+                // THE KERNEL IS NOT STARTED SO CALL NO uC++ ROUTINES!
+                char helpText[256];
+                __attribute__((unused)) int len = snprintf( helpText, 256, " __kernel_sigaction( sig:%d, handler:%p, flags:%d ), problem installing signal handler, error(%d) %s.\n",
+                                sig, handler, flags, errno, strerror( errno ) );
+                LIB_DEBUG_WRITE( STDERR_FILENO, helpText, len );
+                _exit( EXIT_FAILURE );
+        } // if
+}