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: Remove malloc for read/write queues
   9  */
  10 #define DEBUG   0
  11 #include <acess.h>
  12 #include "vfs.h"
  13 #include "vfs_int.h"
  14 #include "vfs_ext.h"
  15 #include <semaphore.h>
  16 #include <threads.h>
  17 #include <events.h>
  18 #include <timers.h>
  19
  20 // === CONSTANTS ===
  21 #define NUM_THREADS_PER_ALLOC   4
  22
  23 // === TYPES ===
  24 typedef struct sVFS_SelectListEnt       tVFS_SelectListEnt;
  25
  26 // === STRUCTURES ===
  27 struct sVFS_SelectListEnt
  28 {
  29         tVFS_SelectListEnt      *Next;
  30         tThread *Threads[NUM_THREADS_PER_ALLOC];
  31 };
  32
  33 // NOTE: Typedef is in vfs.h
  34 struct sVFS_SelectList
  35 {
  36         tMutex  Lock;
  37         tVFS_SelectListEnt      FirstEnt;
  38 };
  39
  40 // === PROTOTYPES ===
  41 // int  VFS_SelectNode(tVFS_Node *Node, enum eVFS_SelectTypes Type, tTime *Timeout);
  42 // int  VFS_Select(int MaxHandle, fd_set *ReadHandles, fd_set *WriteHandles, fd_set *ErrHandles, tTime *Timeout, Uint32 ExtraEvents, BOOL IsKernel);
  43 // int  VFS_MarkFull(tVFS_Node *Node, BOOL IsBufferFull);
  44 // int  VFS_MarkAvaliable(tVFS_Node *Node, BOOL IsDataAvaliable);
  45 // int  VFS_MarkError(tVFS_Node *Node, BOOL IsErrorState);
  46  int    VFS_int_Select_GetType(int Type, tVFS_Node *Node, tVFS_SelectList ***List, int **Flag, int *WantedFlag, int *MaxAllowed);
  47  int    VFS_int_Select_Register(tThread *Thread, int MaxHandle, fd_set *Handles, int Type, BOOL IsKernel);
  48  int    VFS_int_Select_Deregister(tThread *Thread, int MaxHandle, fd_set *Handles, int Type, BOOL IsKernel);
  49  int    VFS_int_Select_AddThread(tVFS_SelectList *List, tThread *Thread, int MaxAllowed);
  50 void    VFS_int_Select_RemThread(tVFS_SelectList *List, tThread *Thread);
  51 void    VFS_int_Select_SignalAll(tVFS_SelectList *List);
  52
  53 // === GLOBALS ===
  54
  55 // === FUNCTIONS ===
  56 int VFS_SelectNode(tVFS_Node *Node, int TypeFlags, tTime *Timeout, const char *Name)
  57 {
  58         tThread *thisthread = Proc_GetCurThread();
  59          int    ret, type;
  60
  61         ENTER("pNode iTypeFlags pTimeout sName", Node, TypeFlags, Timeout, Name);
  62
  63         // Initialise
  64         for( type = 0; type < 3; type ++ )
  65         {
  66                 tVFS_SelectList **list;
  67                  int    *flag, wanted, maxAllowed;
  68                 if( !(TypeFlags & (1 << type)) )        continue;
  69                 if( VFS_int_Select_GetType(type, Node, &list, &flag, &wanted, &maxAllowed) ) {
  70                         LEAVE('i', -1);
  71                         return -1;
  72                 }
  73
  74                 // Alloc if needed
  75                 if( !*list )    *list = calloc(1, sizeof(tVFS_SelectList));
  76
  77                 VFS_int_Select_AddThread(*list, thisthread, maxAllowed);
  78                 if( *flag == wanted )
  79                 {
  80                         VFS_int_Select_RemThread(*list, thisthread);
  81                         LEAVE('i', 1);
  82                         return 1;
  83                 }
  84         }
  85
  86         // Wait for things
  87         if( !Timeout )
  88         {
  89                 LOG("Semaphore_Wait()");
  90                 // TODO: Actual timeout
  91                 Threads_WaitEvents( THREAD_EVENT_VFS|THREAD_EVENT_SIGNAL );
  92         }
  93         else if( *Timeout > 0 )
  94         {
  95                 tTimer *t = Time_AllocateTimer(NULL, NULL);
  96                 // Clear timer event
  97                 Threads_ClearEvent( THREAD_EVENT_TIMER );
  98                 // TODO: Convert *Timeout?
  99                 LOG("Timeout %lli ms", *Timeout);
 100                 Time_ScheduleTimer( t, *Timeout );
 101                 // Wait for the timer or a VFS event
 102                 Threads_WaitEvents( THREAD_EVENT_VFS|THREAD_EVENT_TIMER|THREAD_EVENT_SIGNAL );
 103                 Time_FreeTimer(t);
 104         }
 105
 106         // Get return value
 107         ret = 0;
 108         for( type = 0; type < 3; type ++ )
 109         {
 110                 tVFS_SelectList **list;
 111                  int    *flag, wanted, maxAllowed;
 112                 if( !(TypeFlags & (1 << type)) )        continue;
 113                 VFS_int_Select_GetType(type, Node, &list, &flag, &wanted, &maxAllowed);
 114                 LOG("VFS_int_Select_RemThread()");
 115                 ASSERT(*list);
 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("Waiting for VFS/SIGNAL events (Plus 0x%x)", ExtraEvents);
 167                 // TODO: Actual timeout
 168                 Threads_WaitEvents( THREAD_EVENT_VFS|THREAD_EVENT_SIGNAL|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         LOG("De-registering");
 184         // - Also, de-register
 185         ret  = VFS_int_Select_Deregister(thisthread, MaxHandle, ReadHandles, 0, IsKernel);
 186         ret += VFS_int_Select_Deregister(thisthread, MaxHandle, WriteHandles, 1, IsKernel);
 187         ret += VFS_int_Select_Deregister(thisthread, MaxHandle, ErrHandles, 2, IsKernel);
 188
 189         Threads_ClearEvent( THREAD_EVENT_VFS );
 190         Threads_ClearEvent( THREAD_EVENT_TIMER );
 191
 192         LEAVE('i', ret);
 193         return ret;
 194 }
 195
 196 // Mark a node as having data ready for reading
 197 int VFS_MarkAvaliable(tVFS_Node *Node, BOOL IsDataAvaliable)
 198 {
 199         ENTER("pNode bIsDataAvaliable", Node, IsDataAvaliable);
 200         Node->DataAvaliable = !!IsDataAvaliable;
 201         if( Node->DataAvaliable )
 202                 VFS_int_Select_SignalAll(Node->ReadThreads);
 203         LEAVE('i', 0);
 204         return 0;
 205 }
 206
 207 // Mark a node as having a full buffer
 208 int VFS_MarkFull(tVFS_Node *Node, BOOL IsBufferFull)
 209 {
 210         ENTER("pNode bIsBufferFull", Node, IsBufferFull);
 211         Node->BufferFull = !!IsBufferFull;
 212         if( !Node->BufferFull )
 213                 VFS_int_Select_SignalAll(Node->WriteThreads);
 214         LEAVE('i', 0);
 215         return 0;
 216 }
 217
 218 // Mark a node as errored
 219 int VFS_MarkError(tVFS_Node *Node, BOOL IsErrorState)
 220 {
 221         ENTER("pNode bIsErrorState", Node, IsErrorState);
 222         Node->ErrorOccurred = !!IsErrorState;
 223         if( Node->ErrorOccurred )
 224                 VFS_int_Select_SignalAll(Node->ErrorThreads);
 225         LEAVE('i', 0);
 226         return 0;
 227 }
 228
 229 // --- Internal ---
 230 int VFS_int_Select_GetType(int Type, tVFS_Node *Node, tVFS_SelectList ***List, int **Flag, int *WantedFlag, int *MaxAllowed)
 231 {
 232         // Get the type of the listen
 233         switch(Type)
 234         {
 235         case 0: // Read
 236                 if(List)        *List = &Node->ReadThreads;
 237                 if(Flag)        *Flag = &Node->DataAvaliable;
 238                 if(WantedFlag)  *WantedFlag = 1;
 239                 if(MaxAllowed)  *MaxAllowed = 1;        // Max of 1 for read
 240                 break;
 241         case 1: // Write
 242                 if(List)        *List = &Node->WriteThreads;
 243                 if(Flag)        *Flag = &Node->BufferFull;
 244                 if(WantedFlag)  *WantedFlag = 0;
 245                 if(MaxAllowed)  *MaxAllowed = 1;        // Max of 1 for write
 246                 break;
 247         case 2: // Error
 248                 if(List)        *List = &Node->ErrorThreads;
 249                 if(Flag)        *Flag = &Node->ErrorOccurred;
 250                 if(WantedFlag)  *WantedFlag = 1;
 251                 if(MaxAllowed)  *MaxAllowed = -1;       // No max for error listeners
 252                 break;
 253         default:
 254                 Log_Error("VFS", "VFS_int_Select_GetType: BUG CHECK, Unknown Type %i", Type);
 255                 return 1;
 256         }
 257         return 0;
 258 }
 259
 260 /**
 261  * \return Number of files with an action
 262  */
 263 int VFS_int_Select_Register(tThread *Thread, int MaxHandle, fd_set *Handles, int Type, BOOL IsKernel)
 264 {
 265          int    i, numFlagged = 0;
 266         tVFS_SelectList **list;
 267          int    *flag, wantedFlagValue;
 268          int    maxAllowed;
 269
 270         if( !Handles )  return 0;
 271
 272         ENTER("pThread iMaxHandle pHandles iType iIsKernel", Thread, MaxHandle, Handles, Type, IsKernel);
 273
 274         for( i = 0; i < MaxHandle; i ++ )
 275         {
 276                 tVFS_Handle     *handle;
 277
 278                 // Is the descriptor set
 279                 if( !FD_ISSET(i, Handles) )     continue;
 280                 LOG("FD #%i", i);
 281
 282                 handle = VFS_GetHandle( i | (IsKernel?VFS_KERNEL_FLAG:0) );
 283                 // Is the handle valid?
 284                 if( !handle || !handle->Node )
 285                 {
 286                         if( Type == 2 ) {       // Bad FD counts as an error
 287                                 numFlagged ++;
 288                         }
 289                         else {
 290                                 FD_CLR(i, Handles);
 291                         }
 292                         continue;
 293                 }
 294
 295                 // Get the type of the listen
 296                 if( VFS_int_Select_GetType(Type, handle->Node, &list, &flag, &wantedFlagValue, &maxAllowed) ) {
 297                         LEAVE('i', 0);
 298                         return 0;
 299                 }
 300
 301                 // Alloc if needed
 302                 if( !*list ) {
 303                         *list = calloc(1, sizeof(tVFS_SelectList));
 304                 }
 305
 306                 // Register
 307                 if( VFS_int_Select_AddThread(*list, Thread, maxAllowed ) )
 308                 {
 309                         // Oops, error (or just no space)
 310                         FD_CLR(i, Handles);
 311                 }
 312
 313                 // Check for the flag
 314                 if( !!*flag == !!wantedFlagValue ) {
 315                         LOG(" %i == want %i", !!*flag, !!wantedFlagValue);
 316                         numFlagged ++;
 317                 }
 318         }
 319
 320         LEAVE('i', numFlagged);
 321
 322         return numFlagged;
 323 }
 324 /**
 325  * \return Number of files with an action
 326  */
 327 int VFS_int_Select_Deregister(tThread *Thread, int MaxHandle, fd_set *Handles, int Type, BOOL IsKernel)
 328 {
 329          int    i, numFlagged = 0;
 330         tVFS_SelectList **list;
 331          int    *flag, wantedFlagValue;
 332
 333         if( !Handles )  return 0;
 334
 335         ENTER("pThread iMaxHandle pHandles iType iIsKernel", Thread, MaxHandle, Handles, Type, IsKernel);
 336
 337         for( i = 0; i < MaxHandle; i ++ )
 338         {
 339                 tVFS_Handle     *handle;
 340
 341                 // Is the descriptor set
 342                 if( !FD_ISSET(i, Handles) )     continue;
 343                 LOG("FD #%i", i);
 344
 345                 handle = VFS_GetHandle( i | (IsKernel?VFS_KERNEL_FLAG:0) );
 346                 // Is the handle valid?
 347                 if( !handle || !handle->Node )
 348                 {
 349                         if( Type == 2 ) {       // Bad FD counts as an error
 350                                 numFlagged ++;
 351                         }
 352                         else {
 353                                 FD_CLR(i, Handles);
 354                         }
 355                         continue;
 356                 }
 357
 358                 // Get the type of the listen
 359                 if( VFS_int_Select_GetType(Type, handle->Node, &list, &flag, &wantedFlagValue, NULL) ) {
 360                         LEAVE('i', 0);
 361                         return 0;
 362                 }
 363
 364                 // Remove
 365                 VFS_int_Select_RemThread(*list, Thread );
 366
 367                 // Check for the flag
 368                 if( !!*flag == !!wantedFlagValue ) {
 369                         numFlagged ++;
 370                         LOG(" %i == want %i", !!*flag, !!wantedFlagValue);
 371                         FD_SET(i, Handles);
 372                 }
 373                 else {
 374                         FD_CLR(i, Handles);
 375                 }
 376         }
 377
 378         LEAVE('i', numFlagged);
 379
 380         return numFlagged;
 381 }
 382
 383 /**
 384  * \return Boolean failure
 385  */
 386 int VFS_int_Select_AddThread(tVFS_SelectList *List, tThread *Thread, int MaxAllowed)
 387 {
 388          int    i, count = 0;
 389         tVFS_SelectListEnt      *block, *prev;
 390
 391         ENTER("pList pThread iMaxAllowed", List, Thread, MaxAllowed);
 392
 393         // Lock to avoid concurrency issues
 394         Mutex_Acquire(&List->Lock);
 395
 396         block = &List->FirstEnt;
 397
 398         // Look for free space
 399         do
 400         {
 401                 for( i = 0; i < NUM_THREADS_PER_ALLOC; i ++ )
 402                 {
 403                         if( block->Threads[i] == NULL )
 404                         {
 405                                 block->Threads[i] = Thread;
 406                                 Mutex_Release(&List->Lock);
 407                                 LEAVE('i', 0);
 408                                 return 0;
 409                         }
 410                         count ++;
 411                         if( MaxAllowed && count >= MaxAllowed ) {
 412                                 Mutex_Release(&List->Lock);
 413                                 LEAVE('i', 1);
 414                                 return 1;
 415                         }
 416                 }
 417
 418                 prev = block;
 419                 block = block->Next;
 420         } while(block);
 421
 422         LOG("New block");
 423
 424         // Create new block
 425         block = malloc( sizeof(tVFS_SelectListEnt) );
 426         if( !block ) {
 427                 Log_Warning("VFS", "VFS_int_Select_AddThread: malloc() failed");
 428                 Mutex_Release(&List->Lock);
 429                 return -1;
 430         }
 431         block->Next = NULL;
 432         block->Threads[0] = Thread;
 433         for( i = 1; i < NUM_THREADS_PER_ALLOC; i ++ )
 434         {
 435                 block->Threads[i] = NULL;
 436         }
 437
 438         // Add to list
 439         prev->Next = block;
 440
 441         // Release
 442         Mutex_Release(&List->Lock);
 443
 444         LEAVE('i', 0);
 445         return 0;
 446 }
 447
 448 void VFS_int_Select_RemThread(tVFS_SelectList *List, tThread *Thread)
 449 {
 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( int 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 }