Kernel/x86 - Removed busy wait in MM_MapTemp

diff --git a/KernelLand/Kernel/arch/x86/mm_virt.c b/KernelLand/Kernel/arch/x86/mm_virt.c
index 216bc1e..b81698c 100644 (file)
--- a/KernelLand/Kernel/arch/x86/mm_virt.c
+++ b/KernelLand/Kernel/arch/x86/mm_virt.c
@@ -17,6 +17,7 @@
 #include <proc.h>
 #include <hal_proc.h>
 #include <arch_int.h>
+#include <semaphore.h>
 
 #define TAB    22
 
@@ -97,6 +98,7 @@ tPAddr        MM_DuplicatePage(tVAddr VAddr);
 #define gaPAE_TmpPDPT  ((tTabEnt*)PAE_TMP_PDPT_ADDR)
  int   gbUsePAE = 0;
 tMutex glTempMappings;
+tSemaphore     gTempMappingsSem;
 tMutex glTempFractal;
 Uint32 gWorkerStacks[(NUM_WORKER_STACKS+31)/32];
  int   giLastUsedWorker = 0;
@@ -117,6 +119,8 @@ void MM_PreinitVirtual(void)
 {
        gaInitPageDir[ PAGE_TABLE_ADDR >> 22 ] = ((tTabEnt)&gaInitPageDir - KERNEL_BASE) | 3;
        INVLPG( PAGE_TABLE_ADDR );
+       
+       Semaphore_Init(&gTempMappingsSem, NUM_TEMP_PAGES, NUM_TEMP_PAGES, "MMVirt", "Temp Mappings");
 }
 
 /**
@@ -980,32 +984,29 @@ tPAddr MM_DuplicatePage(tVAddr VAddr)
  */
 void * MM_MapTemp(tPAddr PAddr)
 {
-        int    i;
-       
        //ENTER("XPAddr", PAddr);
        
        PAddr &= ~0xFFF;
        
        //LOG("glTempMappings = %i", glTempMappings);
        
-       for(;;)
+       if( Semaphore_Wait(&gTempMappingsSem, 1) != 1 )
+               return NULL;
+       Mutex_Acquire( &glTempMappings );
+       for( int i = 0; i < NUM_TEMP_PAGES; i ++ )
        {
-               Mutex_Acquire( &glTempMappings );
-               
-               for( i = 0; i < NUM_TEMP_PAGES; i ++ )
-               {
-                       // Check if page used
-                       if(gaPageTable[ (TEMP_MAP_ADDR >> 12) + i ] & 1)        continue;
-                       // Mark as used
-                       gaPageTable[ (TEMP_MAP_ADDR >> 12) + i ] = PAddr | 3;
-                       INVLPG( TEMP_MAP_ADDR + (i << 12) );
-                       //LEAVE('p', TEMP_MAP_ADDR + (i << 12));
-                       Mutex_Release( &glTempMappings );
-                       return (void*)( TEMP_MAP_ADDR + (i << 12) );
-               }
+               // Check if page used
+               if(gaPageTable[ (TEMP_MAP_ADDR >> 12) + i ] & 1)        continue;
+               // Mark as used
+               gaPageTable[ (TEMP_MAP_ADDR >> 12) + i ] = PAddr | 3;
+               INVLPG( TEMP_MAP_ADDR + (i << 12) );
+               //LEAVE('p', TEMP_MAP_ADDR + (i << 12));
                Mutex_Release( &glTempMappings );
-               Threads_Yield();        // TODO: Use a sleep queue here instead
+               return (void*)( TEMP_MAP_ADDR + (i << 12) );
        }
+       Mutex_Release( &glTempMappings );
+       Log_KernelPanic("MMVirt", "Semaphore suplied a mapping, but none are avaliable");
+       return NULL;
 }
 
 /**
@@ -1017,8 +1018,10 @@ void MM_FreeTemp(void *VAddr)
         int    i = (tVAddr)VAddr >> 12;
        //ENTER("xVAddr", VAddr);
        
-       if(i >= (TEMP_MAP_ADDR >> 12))
+       if(i >= (TEMP_MAP_ADDR >> 12)) {
                gaPageTable[ i ] = 0;
+               Semaphore_Signal(&gTempMappingsSem, 1);
+       }
        
        //LEAVE('-');
 }