KernelLand/Kernel/vfs/select.c

   1 /*
   2  * Acess2 VFS
   3  * - By thePowersGang (John Hodge)
   4  *
   5  * select.c
   6  * - Implements the select() system call (and supporting code)
   7  *
   8  * TODO: Implment timeouts (via an alarm event?)
   9  * TODO: Remove malloc for read/write queues
  10  */
  11 #define DEBUG   0
  12 #include <acess.h>
  13 #include "vfs.h"
  14 #include "vfs_int.h"
  15 #include "vfs_ext.h"
  16 #include <semaphore.h>
  17 #include <threads.h>
  18 #include <events.h>
  19 #include <timers.h>
  20
  21 // === CONSTANTS ===
  22 #define NUM_THREADS_PER_ALLOC   4
  23
  24 // === TYPES ===
  25 typedef struct sVFS_SelectListEnt       tVFS_SelectListEnt;
  26
  27 // === STRUCTURES ===
  28 struct sVFS_SelectListEnt
  29 {
  30         tVFS_SelectListEnt      *Next;
  31         tThread *Threads[NUM_THREADS_PER_ALLOC];
  32 };
  33
  34 // NOTE: Typedef is in vfs.h
  35 struct sVFS_SelectList
  36 {
  37         tMutex  Lock;
  38         tVFS_SelectListEnt      FirstEnt;
  39 };
  40
  41 // === PROTOTYPES ===
  42 // int  VFS_SelectNode(tVFS_Node *Node, enum eVFS_SelectTypes Type, tTime *Timeout);
  43 // int  VFS_Select(int MaxHandle, fd_set *ReadHandles, fd_set *WriteHandles, fd_set *ErrHandles, tTime *Timeout, Uint32 ExtraEvents, BOOL IsKernel);
  44 // int  VFS_MarkFull(tVFS_Node *Node, BOOL IsBufferFull);
  45 // int  VFS_MarkAvaliable(tVFS_Node *Node, BOOL IsDataAvaliable);
  46 // int  VFS_MarkError(tVFS_Node *Node, BOOL IsErrorState);
  47  int    VFS_int_Select_GetType(int Type, tVFS_Node *Node, tVFS_SelectList ***List, int **Flag, int *WantedFlag, int *MaxAllowed);
  48  int    VFS_int_Select_Register(tThread *Thread, int MaxHandle, fd_set *Handles, int Type, BOOL IsKernel);
  49  int    VFS_int_Select_Deregister(tThread *Thread, int MaxHandle, fd_set *Handles, int Type, BOOL IsKernel);
  50  int    VFS_int_Select_AddThread(tVFS_SelectList *List, tThread *Thread, int MaxAllowed);
  51 void    VFS_int_Select_RemThread(tVFS_SelectList *List, tThread *Thread);
  52 void    VFS_int_Select_SignalAll(tVFS_SelectList *List);
  53
  54 // === GLOBALS ===
  55
  56 // === FUNCTIONS ===
  57 int VFS_SelectNode(tVFS_Node *Node, int TypeFlags, tTime *Timeout, const char *Name)
  58 {
  59         tThread *thisthread = Proc_GetCurThread();
  60          int    ret, type;
  61
  62         ENTER("pNode iTypeFlags pTimeout sName", Node, TypeFlags, Timeout, Name);
  63
  64         // Initialise
  65         for( type = 0; type < 3; type ++ )
  66         {
  67                 tVFS_SelectList **list;
  68                  int    *flag, wanted, maxAllowed;
  69                 if( !(TypeFlags & (1 << type)) )        continue;
  70                 if( VFS_int_Select_GetType(type, Node, &list, &flag, &wanted, &maxAllowed) ) {
  71                         LEAVE('i', -1);
  72                         return -1;
  73                 }
  74
  75                 // Alloc if needed
  76                 if( !*list )    *list = calloc(1, sizeof(tVFS_SelectList));
  77
  78                 VFS_int_Select_AddThread(*list, thisthread, maxAllowed);
  79                 if( *flag == wanted )
  80                 {
  81                         VFS_int_Select_RemThread(*list, thisthread);
  82                         LEAVE('i', 1);
  83                         return 1;
  84                 }
  85         }
  86
  87         // Wait for things
  88         if( !Timeout )
  89         {
  90                 LOG("Semaphore_Wait()");
  91                 // TODO: Actual timeout
  92                 Threads_WaitEvents( THREAD_EVENT_VFS );
  93         }
  94         else if( *Timeout > 0 )
  95         {
  96                 tTimer *t = Time_AllocateTimer(NULL, NULL);
  97                 // Clear timer event
  98                 Threads_ClearEvent( THREAD_EVENT_TIMER );
  99                 // TODO: Convert *Timeout?
 100                 LOG("Timeout %lli ms", *Timeout);
 101                 Time_ScheduleTimer( t, *Timeout );
 102                 // Wait for the timer or a VFS event
 103                 Threads_WaitEvents( THREAD_EVENT_VFS|THREAD_EVENT_TIMER );
 104                 Time_FreeTimer(t);
 105         }
 106
 107         // Get return value
 108         ret = 0;
 109         for( type = 0; type < 3; type ++ )
 110         {
 111                 tVFS_SelectList **list;
 112                  int    *flag, wanted, maxAllowed;
 113                 if( !(TypeFlags & (1 << type)) )        continue;
 114                 VFS_int_Select_GetType(type, Node, &list, &flag, &wanted, &maxAllowed);
 115                 LOG("VFS_int_Select_RemThread()");
 116                 VFS_int_Select_RemThread(*list, thisthread);
 117                 ret = ret || *flag == wanted;
 118         }
 119
 120         Threads_ClearEvent( THREAD_EVENT_VFS );
 121         Threads_ClearEvent( THREAD_EVENT_TIMER );
 122
 123         LEAVE('i', ret);
 124         return ret;
 125 }
 126
 127 int VFS_Select(int MaxHandle, fd_set *ReadHandles, fd_set *WriteHandles, fd_set *ErrHandles, tTime *Timeout, Uint32 ExtraEvents, BOOL IsKernel)
 128 {
 129         tThread *thisthread = Proc_GetCurThread();
 130          int    ret;
 131
 132         ENTER("iMaxHandle pReadHandles pWriteHandles pErrHandles pTimeout xExtraEvents bIsKernel",
 133                 MaxHandle, ReadHandles, WriteHandles, ErrHandles, Timeout, ExtraEvents, IsKernel);
 134
 135         // Notes: The idea is to make sure we only enter wait (Threads_WaitEvents)
 136         // if we are going to be woken up (either by an event at a later time,
 137         // or by an event that happened while or before we were registering).
 138         // Hence, register must happen _before_ we check the state flag
 139         // (See VFS_int_Select_Register), that way either we pick up the flag,
 140         // or the semaphore is incremeneted (or both, but never none)
 141
 142         // Register with nodes
 143         if( ReadHandles )
 144                 LOG(" - ReadHandles[0] = %x", ReadHandles->flags[0]);
 145         ret  = VFS_int_Select_Register(thisthread, MaxHandle, ReadHandles, 0, IsKernel);
 146         ret += VFS_int_Select_Register(thisthread, MaxHandle, WriteHandles, 1, IsKernel);
 147         ret += VFS_int_Select_Register(thisthread, MaxHandle, ErrHandles, 2, IsKernel);
 148
 149         LOG("Register ret = %i", ret);
 150
 151         // If there were events waiting, de-register and return
 152         if( ret > 0 )
 153         {
 154                 LOG(" - ReadHandles[0] = %x", ReadHandles->flags[0]);
 155                 ret  = VFS_int_Select_Deregister(thisthread, MaxHandle, ReadHandles, 0, IsKernel);
 156                 ret += VFS_int_Select_Deregister(thisthread, MaxHandle, WriteHandles, 1, IsKernel);
 157                 ret += VFS_int_Select_Deregister(thisthread, MaxHandle, ErrHandles, 2, IsKernel);
 158                 LOG(" - ReadHandles[0] = %x", ReadHandles->flags[0]);
 159                 LEAVE('i', ret);
 160                 return ret;
 161         }
 162
 163         // Wait for things
 164         if( !Timeout )
 165         {
 166                 LOG("Semaphore_Wait()");
 167                 // TODO: Actual timeout
 168                 Threads_WaitEvents( THREAD_EVENT_VFS|ExtraEvents );
 169         }
 170         else if( *Timeout > 0 )
 171         {
 172                 tTimer *t = Time_AllocateTimer(NULL, NULL);
 173                 // Clear timer event
 174                 Threads_ClearEvent( THREAD_EVENT_TIMER );
 175                 // TODO: Convert *Timeout?
 176                 LOG("Timeout %lli ms", *Timeout);
 177                 Time_ScheduleTimer( t, *Timeout );
 178                 // Wait for the timer or a VFS event
 179                 Threads_WaitEvents( THREAD_EVENT_VFS|THREAD_EVENT_TIMER|ExtraEvents );
 180                 Time_FreeTimer(t);
 181         }
 182         // Fill output (modify *Handles)
 183         // - Also, de-register
 184         ret  = VFS_int_Select_Deregister(thisthread, MaxHandle, ReadHandles, 0, IsKernel);
 185         ret += VFS_int_Select_Deregister(thisthread, MaxHandle, WriteHandles, 1, IsKernel);
 186         ret += VFS_int_Select_Deregister(thisthread, MaxHandle, ErrHandles, 2, IsKernel);
 187
 188         Threads_ClearEvent( THREAD_EVENT_VFS );
 189         Threads_ClearEvent( THREAD_EVENT_TIMER );
 190
 191         LEAVE('i', ret);
 192         return ret;
 193 }
 194
 195 // Mark a node as having data ready for reading
 196 int VFS_MarkAvaliable(tVFS_Node *Node, BOOL IsDataAvaliable)
 197 {
 198         ENTER("pNode bIsDataAvaliable", Node, IsDataAvaliable);
 199         Node->DataAvaliable = !!IsDataAvaliable;
 200         if( Node->DataAvaliable )
 201                 VFS_int_Select_SignalAll(Node->ReadThreads);
 202         LEAVE('i', 0);
 203         return 0;
 204 }
 205
 206 // Mark a node as having a full buffer
 207 int VFS_MarkFull(tVFS_Node *Node, BOOL IsBufferFull)
 208 {
 209         ENTER("pNode bIsBufferFull", Node, IsBufferFull);
 210         Node->BufferFull = !!IsBufferFull;
 211         if( !Node->BufferFull )
 212                 VFS_int_Select_SignalAll(Node->WriteThreads);
 213         LEAVE('i', 0);
 214         return 0;
 215 }
 216
 217 // Mark a node as errored
 218 int VFS_MarkError(tVFS_Node *Node, BOOL IsErrorState)
 219 {
 220         ENTER("pNode bIsErrorState", Node, IsErrorState);
 221         Node->ErrorOccurred = !!IsErrorState;
 222         if( Node->ErrorOccurred )
 223                 VFS_int_Select_SignalAll(Node->ErrorThreads);
 224         LEAVE('i', 0);
 225         return 0;
 226 }
 227
 228 // --- Internal ---
 229 int VFS_int_Select_GetType(int Type, tVFS_Node *Node, tVFS_SelectList ***List, int **Flag, int *WantedFlag, int *MaxAllowed)
 230 {
 231         // Get the type of the listen
 232         switch(Type)
 233         {
 234         case 0: // Read
 235                 if(List)        *List = &Node->ReadThreads;
 236                 if(Flag)        *Flag = &Node->DataAvaliable;
 237                 if(WantedFlag)  *WantedFlag = 1;
 238                 if(MaxAllowed)  *MaxAllowed = 1;        // Max of 1 for read
 239                 break;
 240         case 1: // Write
 241                 if(List)        *List = &Node->WriteThreads;
 242                 if(Flag)        *Flag = &Node->BufferFull;
 243                 if(WantedFlag)  *WantedFlag = 0;
 244                 if(MaxAllowed)  *MaxAllowed = 1;        // Max of 1 for write
 245                 break;
 246         case 2: // Error
 247                 if(List)        *List = &Node->ErrorThreads;
 248                 if(Flag)        *Flag = &Node->ErrorOccurred;
 249                 if(WantedFlag)  *WantedFlag = 1;
 250                 if(MaxAllowed)  *MaxAllowed = -1;       // No max for error listeners
 251                 break;
 252         default:
 253                 Log_Error("VFS", "VFS_int_Select_GetType: BUG CHECK, Unknown Type %i", Type);
 254                 return 1;
 255         }
 256         return 0;
 257 }
 258
 259 /**
 260  * \return Number of files with an action
 261  */
 262 int VFS_int_Select_Register(tThread *Thread, int MaxHandle, fd_set *Handles, int Type, BOOL IsKernel)
 263 {
 264          int    i, numFlagged = 0;
 265         tVFS_SelectList **list;
 266          int    *flag, wantedFlagValue;
 267          int    maxAllowed;
 268
 269         if( !Handles )  return 0;
 270
 271         ENTER("pThread iMaxHandle pHandles iType iIsKernel", Thread, MaxHandle, Handles, Type, IsKernel);
 272
 273         for( i = 0; i < MaxHandle; i ++ )
 274         {
 275                 tVFS_Handle     *handle;
 276
 277                 // Is the descriptor set
 278                 if( !FD_ISSET(i, Handles) )     continue;
 279                 LOG("FD #%i", i);
 280
 281                 handle = VFS_GetHandle( i | (IsKernel?VFS_KERNEL_FLAG:0) );
 282                 // Is the handle valid?
 283                 if( !handle || !handle->Node )
 284                 {
 285                         if( Type == 2 ) {       // Bad FD counts as an error
 286                                 numFlagged ++;
 287                         }
 288                         else {
 289                                 FD_CLR(i, Handles);
 290                         }
 291                         continue;
 292                 }
 293
 294                 // Get the type of the listen
 295                 if( VFS_int_Select_GetType(Type, handle->Node, &list, &flag, &wantedFlagValue, &maxAllowed) ) {
 296                         LEAVE('i', 0);
 297                         return 0;
 298                 }
 299
 300                 // Alloc if needed
 301                 if( !*list ) {
 302                         *list = calloc(1, sizeof(tVFS_SelectList));
 303                 }
 304
 305                 // Register
 306                 if( VFS_int_Select_AddThread(*list, Thread, maxAllowed ) )
 307                 {
 308                         // Oops, error (or just no space)
 309                         FD_CLR(i, Handles);
 310                 }
 311
 312                 // Check for the flag
 313                 if( !!*flag == !!wantedFlagValue ) {
 314                         LOG(" %i == want %i", !!*flag, !!wantedFlagValue);
 315                         numFlagged ++;
 316                 }
 317         }
 318
 319         LEAVE('i', numFlagged);
 320
 321         return numFlagged;
 322 }
 323 /**
 324  * \return Number of files with an action
 325  */
 326 int VFS_int_Select_Deregister(tThread *Thread, int MaxHandle, fd_set *Handles, int Type, BOOL IsKernel)
 327 {
 328          int    i, numFlagged = 0;
 329         tVFS_SelectList **list;
 330          int    *flag, wantedFlagValue;
 331
 332         if( !Handles )  return 0;
 333
 334         ENTER("pThread iMaxHandle pHandles iType iIsKernel", Thread, MaxHandle, Handles, Type, IsKernel);
 335
 336         for( i = 0; i < MaxHandle; i ++ )
 337         {
 338                 tVFS_Handle     *handle;
 339
 340                 // Is the descriptor set
 341                 if( !FD_ISSET(i, Handles) )     continue;
 342                 LOG("FD #%i", i);
 343
 344                 handle = VFS_GetHandle( i | (IsKernel?VFS_KERNEL_FLAG:0) );
 345                 // Is the handle valid?
 346                 if( !handle || !handle->Node )
 347                 {
 348                         if( Type == 2 ) {       // Bad FD counts as an error
 349                                 numFlagged ++;
 350                         }
 351                         else {
 352                                 FD_CLR(i, Handles);
 353                         }
 354                         continue;
 355                 }
 356
 357                 // Get the type of the listen
 358                 if( VFS_int_Select_GetType(Type, handle->Node, &list, &flag, &wantedFlagValue, NULL) ) {
 359                         LEAVE('i', 0);
 360                         return 0;
 361                 }
 362
 363                 // Remove
 364                 VFS_int_Select_RemThread(*list, Thread );
 365
 366                 // Check for the flag
 367                 if( !!*flag == !!wantedFlagValue ) {
 368                         numFlagged ++;
 369                         LOG(" %i == want %i", !!*flag, !!wantedFlagValue);
 370                         FD_SET(i, Handles);
 371                 }
 372                 else {
 373                         FD_CLR(i, Handles);
 374                 }
 375         }
 376
 377         LEAVE('i', numFlagged);
 378
 379         return numFlagged;
 380 }
 381
 382 /**
 383  * \return Boolean failure
 384  */
 385 int VFS_int_Select_AddThread(tVFS_SelectList *List, tThread *Thread, int MaxAllowed)
 386 {
 387          int    i, count = 0;
 388         tVFS_SelectListEnt      *block, *prev;
 389
 390         ENTER("pList pThread iMaxAllowed", List, Thread, MaxAllowed);
 391
 392         // Lock to avoid concurrency issues
 393         Mutex_Acquire(&List->Lock);
 394
 395         block = &List->FirstEnt;
 396
 397         // Look for free space
 398         do
 399         {
 400                 for( i = 0; i < NUM_THREADS_PER_ALLOC; i ++ )
 401                 {
 402                         if( block->Threads[i] == NULL )
 403                         {
 404                                 block->Threads[i] = Thread;
 405                                 Mutex_Release(&List->Lock);
 406                                 LEAVE('i', 0);
 407                                 return 0;
 408                         }
 409                         count ++;
 410                         if( MaxAllowed && count >= MaxAllowed ) {
 411                                 Mutex_Release(&List->Lock);
 412                                 LEAVE('i', 1);
 413                                 return 1;
 414                         }
 415                 }
 416
 417                 prev = block;
 418                 block = block->Next;
 419         } while(block);
 420
 421         LOG("New block");
 422
 423         // Create new block
 424         block = malloc( sizeof(tVFS_SelectListEnt) );
 425         if( !block ) {
 426                 Log_Warning("VFS", "VFS_int_Select_AddThread: malloc() failed");
 427                 Mutex_Release(&List->Lock);
 428                 return -1;
 429         }
 430         block->Next = NULL;
 431         block->Threads[0] = Thread;
 432         for( i = 1; i < NUM_THREADS_PER_ALLOC; i ++ )
 433         {
 434                 block->Threads[i] = NULL;
 435         }
 436
 437         // Add to list
 438         prev->Next = block;
 439
 440         // Release
 441         Mutex_Release(&List->Lock);
 442
 443         LEAVE('i', 0);
 444         return 0;
 445 }
 446
 447 void VFS_int_Select_RemThread(tVFS_SelectList *List, tThread *Thread)
 448 {
 449          int    i;
 450         tVFS_SelectListEnt      *block, *prev = NULL;
 451
 452         ENTER("pList pThread", List, Thread);
 453
 454         // Lock to avoid concurrency issues
 455         Mutex_Acquire(&List->Lock);
 456
 457         block = &List->FirstEnt;
 458
 459         // Look for the thread
 460         do
 461         {
 462                 for( i = 0; i < NUM_THREADS_PER_ALLOC; i ++ )
 463                 {
 464                         if( block->Threads[i] == Thread )
 465                         {
 466                                 block->Threads[i] = NULL;
 467
 468                                 // Check if this block is empty
 469                                 if( block != &List->FirstEnt )
 470                                 {
 471                                         for( i = 0; i < NUM_THREADS_PER_ALLOC; i ++ )
 472                                                 if( block->Threads[i] )
 473                                                         break;
 474                                         // If empty, free it
 475                                         if( i == NUM_THREADS_PER_ALLOC ) {
 476                                                 LOG("Deleting block");
 477                                                 prev->Next = block->Next;
 478                                                 free(block);
 479                                         }
 480                                         //TODO: If not empty, check if it can be merged downwards
 481                                 }
 482
 483                                 Mutex_Release(&List->Lock);
 484                                 LEAVE('-');
 485                                 return ;
 486                         }
 487                 }
 488
 489                 prev = block;
 490                 block = block->Next;
 491         } while(block);
 492
 493         // Not on list, is this an error?
 494
 495         Mutex_Release(&List->Lock);
 496
 497         LOG("Not on list");
 498         LEAVE('-');
 499 }
 500
 501 /**
 502  * \brief Signal all threads on a list
 503  */
 504 void VFS_int_Select_SignalAll(tVFS_SelectList *List)
 505 {
 506          int    i;
 507         tVFS_SelectListEnt      *block;
 508
 509         if( !List )     return ;
 510
 511         ENTER("pList", List);
 512
 513         // Lock to avoid concurrency issues
 514         Mutex_Acquire(&List->Lock);
 515
 516         block = &List->FirstEnt;
 517
 518         // Look for the thread
 519         do
 520         {
 521                 for( i = 0; i < NUM_THREADS_PER_ALLOC; i ++ )
 522                 {
 523                         if( block->Threads[i]  )
 524                         {
 525                                 LOG("block(%p)->Threads[%i] = %p", block, i, block->Threads[i]);
 526                                 Threads_PostEvent( block->Threads[i], THREAD_EVENT_VFS );
 527                         }
 528                 }
 529
 530                 block = block->Next;
 531         } while(block);
 532
 533         Mutex_Release(&List->Lock);
 534
 535         LEAVE('-');
 536 }