libsanitizer/sanitizer_common/sanitizer_deadlock_detector2.cc

   1 //===-- sanitizer_deadlock_detector2.cc -----------------------------------===//
   2 //
   3 // This file is distributed under the University of Illinois Open Source
   4 // License. See LICENSE.TXT for details.
   5 //
   6 //===----------------------------------------------------------------------===//
   7 //
   8 // Deadlock detector implementation based on adjacency lists.
   9 //
  10 //===----------------------------------------------------------------------===//
  11
  12 #include "sanitizer_deadlock_detector_interface.h"
  13 #include "sanitizer_common.h"
  14 #include "sanitizer_allocator_internal.h"
  15 #include "sanitizer_placement_new.h"
  16 #include "sanitizer_mutex.h"
  17
  18 #if SANITIZER_DEADLOCK_DETECTOR_VERSION == 2
  19
  20 namespace __sanitizer {
  21
  22 const int kMaxNesting = 64;
  23 const u32 kNoId = -1;
  24 const u32 kEndId = -2;
  25 const int kMaxLink = 8;
  26 const int kL1Size = 1024;
  27 const int kL2Size = 1024;
  28 const int kMaxMutex = kL1Size * kL2Size;
  29
  30 struct Id {
  31   u32 id;
  32   u32 seq;
  33
  34   explicit Id(u32 id = 0, u32 seq = 0)
  35       : id(id)
  36       , seq(seq) {
  37   }
  38 };
  39
  40 struct Link {
  41   u32 id;
  42   u32 seq;
  43   u32 tid;
  44   u32 stk0;
  45   u32 stk1;
  46
  47   explicit Link(u32 id = 0, u32 seq = 0, u32 tid = 0, u32 s0 = 0, u32 s1 = 0)
  48       : id(id)
  49       , seq(seq)
  50       , tid(tid)
  51       , stk0(s0)
  52       , stk1(s1) {
  53   }
  54 };
  55
  56 struct DDPhysicalThread {
  57   DDReport rep;
  58   bool report_pending;
  59   bool visited[kMaxMutex];
  60   Link pending[kMaxMutex];
  61   Link path[kMaxMutex];
  62 };
  63
  64 struct ThreadMutex {
  65   u32 id;
  66   u32 stk;
  67 };
  68
  69 struct DDLogicalThread {
  70   u64         ctx;
  71   ThreadMutex locked[kMaxNesting];
  72   int         nlocked;
  73 };
  74
  75 struct Mutex {
  76   StaticSpinMutex mtx;
  77   u32 seq;
  78   int nlink;
  79   Link link[kMaxLink];
  80 };
  81
  82 struct DD : public DDetector {
  83   explicit DD(const DDFlags *flags);
  84
  85   DDPhysicalThread* CreatePhysicalThread();
  86   void DestroyPhysicalThread(DDPhysicalThread *pt);
  87
  88   DDLogicalThread* CreateLogicalThread(u64 ctx);
  89   void DestroyLogicalThread(DDLogicalThread *lt);
  90
  91   void MutexInit(DDCallback *cb, DDMutex *m);
  92   void MutexBeforeLock(DDCallback *cb, DDMutex *m, bool wlock);
  93   void MutexAfterLock(DDCallback *cb, DDMutex *m, bool wlock,
  94       bool trylock);
  95   void MutexBeforeUnlock(DDCallback *cb, DDMutex *m, bool wlock);
  96   void MutexDestroy(DDCallback *cb, DDMutex *m);
  97
  98   DDReport *GetReport(DDCallback *cb);
  99
 100   void CycleCheck(DDPhysicalThread *pt, DDLogicalThread *lt, DDMutex *mtx);
 101   void Report(DDPhysicalThread *pt, DDLogicalThread *lt, int npath);
 102   u32 allocateId(DDCallback *cb);
 103   Mutex *getMutex(u32 id);
 104   u32 getMutexId(Mutex *m);
 105
 106   DDFlags flags;
 107
 108   Mutex* mutex[kL1Size];
 109
 110   SpinMutex mtx;
 111   InternalMmapVector<u32> free_id;
 112   int id_gen;
 113 };
 114
 115 DDetector *DDetector::Create(const DDFlags *flags) {
 116   (void)flags;
 117   void *mem = MmapOrDie(sizeof(DD), "deadlock detector");
 118   return new(mem) DD(flags);
 119 }
 120
 121 DD::DD(const DDFlags *flags)
 122     : flags(*flags)
 123     , free_id(1024) {
 124   id_gen = 0;
 125 }
 126
 127 DDPhysicalThread* DD::CreatePhysicalThread() {
 128   DDPhysicalThread *pt = (DDPhysicalThread*)MmapOrDie(sizeof(DDPhysicalThread),
 129       "deadlock detector (physical thread)");
 130   return pt;
 131 }
 132
 133 void DD::DestroyPhysicalThread(DDPhysicalThread *pt) {
 134   pt->~DDPhysicalThread();
 135   UnmapOrDie(pt, sizeof(DDPhysicalThread));
 136 }
 137
 138 DDLogicalThread* DD::CreateLogicalThread(u64 ctx) {
 139   DDLogicalThread *lt = (DDLogicalThread*)InternalAlloc(
 140       sizeof(DDLogicalThread));
 141   lt->ctx = ctx;
 142   lt->nlocked = 0;
 143   return lt;
 144 }
 145
 146 void DD::DestroyLogicalThread(DDLogicalThread *lt) {
 147   lt->~DDLogicalThread();
 148   InternalFree(lt);
 149 }
 150
 151 void DD::MutexInit(DDCallback *cb, DDMutex *m) {
 152   VPrintf(2, "#%llu: DD::MutexInit(%p)\n", cb->lt->ctx, m);
 153   m->id = kNoId;
 154   m->recursion = 0;
 155   atomic_store(&m->owner, 0, memory_order_relaxed);
 156 }
 157
 158 Mutex *DD::getMutex(u32 id) {
 159   return &mutex[id / kL2Size][id % kL2Size];
 160 }
 161
 162 u32 DD::getMutexId(Mutex *m) {
 163   for (int i = 0; i < kL1Size; i++) {
 164     Mutex *tab = mutex[i];
 165     if (tab == 0)
 166       break;
 167     if (m >= tab && m < tab + kL2Size)
 168       return i * kL2Size + (m - tab);
 169   }
 170   return -1;
 171 }
 172
 173 u32 DD::allocateId(DDCallback *cb) {
 174   u32 id = -1;
 175   SpinMutexLock l(&mtx);
 176   if (free_id.size() > 0) {
 177     id = free_id.back();
 178     free_id.pop_back();
 179   } else {
 180     CHECK_LT(id_gen, kMaxMutex);
 181     if ((id_gen % kL2Size) == 0) {
 182       mutex[id_gen / kL2Size] = (Mutex*)MmapOrDie(kL2Size * sizeof(Mutex),
 183           "deadlock detector (mutex table)");
 184     }
 185     id = id_gen++;
 186   }
 187   CHECK_LE(id, kMaxMutex);
 188   VPrintf(3, "#%llu: DD::allocateId assign id %d\n", cb->lt->ctx, id);
 189   return id;
 190 }
 191
 192 void DD::MutexBeforeLock(DDCallback *cb, DDMutex *m, bool wlock) {
 193   VPrintf(2, "#%llu: DD::MutexBeforeLock(%p, wlock=%d) nlocked=%d\n",
 194       cb->lt->ctx, m, wlock, cb->lt->nlocked);
 195   DDPhysicalThread *pt = cb->pt;
 196   DDLogicalThread *lt = cb->lt;
 197
 198   uptr owner = atomic_load(&m->owner, memory_order_relaxed);
 199   if (owner == (uptr)cb->lt) {
 200     VPrintf(3, "#%llu: DD::MutexBeforeLock recursive\n",
 201         cb->lt->ctx);
 202     return;
 203   }
 204
 205   CHECK_LE(lt->nlocked, kMaxNesting);
 206
 207   // FIXME(dvyukov): don't allocate id if lt->nlocked == 0?
 208   if (m->id == kNoId)
 209     m->id = allocateId(cb);
 210
 211   ThreadMutex *tm = &lt->locked[lt->nlocked++];
 212   tm->id = m->id;
 213   if (flags.second_deadlock_stack)
 214     tm->stk = cb->Unwind();
 215   if (lt->nlocked == 1) {
 216     VPrintf(3, "#%llu: DD::MutexBeforeLock first mutex\n",
 217         cb->lt->ctx);
 218     return;
 219   }
 220
 221   bool added = false;
 222   Mutex *mtx = getMutex(m->id);
 223   for (int i = 0; i < lt->nlocked - 1; i++) {
 224     u32 id1 = lt->locked[i].id;
 225     u32 stk1 = lt->locked[i].stk;
 226     Mutex *mtx1 = getMutex(id1);
 227     SpinMutexLock l(&mtx1->mtx);
 228     if (mtx1->nlink == kMaxLink) {
 229       // FIXME(dvyukov): check stale links
 230       continue;
 231     }
 232     int li = 0;
 233     for (; li < mtx1->nlink; li++) {
 234       Link *link = &mtx1->link[li];
 235       if (link->id == m->id) {
 236         if (link->seq != mtx->seq) {
 237           link->seq = mtx->seq;
 238           link->tid = lt->ctx;
 239           link->stk0 = stk1;
 240           link->stk1 = cb->Unwind();
 241           added = true;
 242           VPrintf(3, "#%llu: DD::MutexBeforeLock added %d->%d link\n",
 243               cb->lt->ctx, getMutexId(mtx1), m->id);
 244         }
 245         break;
 246       }
 247     }
 248     if (li == mtx1->nlink) {
 249       // FIXME(dvyukov): check stale links
 250       Link *link = &mtx1->link[mtx1->nlink++];
 251       link->id = m->id;
 252       link->seq = mtx->seq;
 253       link->tid = lt->ctx;
 254       link->stk0 = stk1;
 255       link->stk1 = cb->Unwind();
 256       added = true;
 257       VPrintf(3, "#%llu: DD::MutexBeforeLock added %d->%d link\n",
 258           cb->lt->ctx, getMutexId(mtx1), m->id);
 259     }
 260   }
 261
 262   if (!added || mtx->nlink == 0) {
 263     VPrintf(3, "#%llu: DD::MutexBeforeLock don't check\n",
 264         cb->lt->ctx);
 265     return;
 266   }
 267
 268   CycleCheck(pt, lt, m);
 269 }
 270
 271 void DD::MutexAfterLock(DDCallback *cb, DDMutex *m, bool wlock,
 272     bool trylock) {
 273   VPrintf(2, "#%llu: DD::MutexAfterLock(%p, wlock=%d, try=%d) nlocked=%d\n",
 274       cb->lt->ctx, m, wlock, trylock, cb->lt->nlocked);
 275   DDLogicalThread *lt = cb->lt;
 276
 277   uptr owner = atomic_load(&m->owner, memory_order_relaxed);
 278   if (owner == (uptr)cb->lt) {
 279     VPrintf(3, "#%llu: DD::MutexAfterLock recursive\n", cb->lt->ctx);
 280     CHECK(wlock);
 281     m->recursion++;
 282     return;
 283   }
 284   CHECK_EQ(owner, 0);
 285   if (wlock) {
 286     VPrintf(3, "#%llu: DD::MutexAfterLock set owner\n", cb->lt->ctx);
 287     CHECK_EQ(m->recursion, 0);
 288     m->recursion = 1;
 289     atomic_store(&m->owner, (uptr)cb->lt, memory_order_relaxed);
 290   }
 291
 292   if (!trylock)
 293     return;
 294
 295   CHECK_LE(lt->nlocked, kMaxNesting);
 296   if (m->id == kNoId)
 297     m->id = allocateId(cb);
 298   ThreadMutex *tm = &lt->locked[lt->nlocked++];
 299   tm->id = m->id;
 300   if (flags.second_deadlock_stack)
 301     tm->stk = cb->Unwind();
 302 }
 303
 304 void DD::MutexBeforeUnlock(DDCallback *cb, DDMutex *m, bool wlock) {
 305   VPrintf(2, "#%llu: DD::MutexBeforeUnlock(%p, wlock=%d) nlocked=%d\n",
 306       cb->lt->ctx, m, wlock, cb->lt->nlocked);
 307   DDLogicalThread *lt = cb->lt;
 308
 309   uptr owner = atomic_load(&m->owner, memory_order_relaxed);
 310   if (owner == (uptr)cb->lt) {
 311     VPrintf(3, "#%llu: DD::MutexBeforeUnlock recursive\n", cb->lt->ctx);
 312     if (--m->recursion > 0)
 313       return;
 314     VPrintf(3, "#%llu: DD::MutexBeforeUnlock reset owner\n", cb->lt->ctx);
 315     atomic_store(&m->owner, 0, memory_order_relaxed);
 316   }
 317   CHECK_NE(m->id, kNoId);
 318   int last = lt->nlocked - 1;
 319   for (int i = last; i >= 0; i--) {
 320     if (cb->lt->locked[i].id == m->id) {
 321       lt->locked[i] = lt->locked[last];
 322       lt->nlocked--;
 323       break;
 324     }
 325   }
 326 }
 327
 328 void DD::MutexDestroy(DDCallback *cb, DDMutex *m) {
 329   VPrintf(2, "#%llu: DD::MutexDestroy(%p)\n",
 330       cb->lt->ctx, m);
 331   DDLogicalThread *lt = cb->lt;
 332
 333   if (m->id == kNoId)
 334     return;
 335
 336   // Remove the mutex from lt->locked if there.
 337   int last = lt->nlocked - 1;
 338   for (int i = last; i >= 0; i--) {
 339     if (lt->locked[i].id == m->id) {
 340       lt->locked[i] = lt->locked[last];
 341       lt->nlocked--;
 342       break;
 343     }
 344   }
 345
 346   // Clear and invalidate the mutex descriptor.
 347   {
 348     Mutex *mtx = getMutex(m->id);
 349     SpinMutexLock l(&mtx->mtx);
 350     mtx->seq++;
 351     mtx->nlink = 0;
 352   }
 353
 354   // Return id to cache.
 355   {
 356     SpinMutexLock l(&mtx);
 357     free_id.push_back(m->id);
 358   }
 359 }
 360
 361 void DD::CycleCheck(DDPhysicalThread *pt, DDLogicalThread *lt,
 362     DDMutex *m) {
 363   internal_memset(pt->visited, 0, sizeof(pt->visited));
 364   int npath = 0;
 365   int npending = 0;
 366   {
 367     Mutex *mtx = getMutex(m->id);
 368     SpinMutexLock l(&mtx->mtx);
 369     for (int li = 0; li < mtx->nlink; li++)
 370       pt->pending[npending++] = mtx->link[li];
 371   }
 372   while (npending > 0) {
 373     Link link = pt->pending[--npending];
 374     if (link.id == kEndId) {
 375       npath--;
 376       continue;
 377     }
 378     if (pt->visited[link.id])
 379       continue;
 380     Mutex *mtx1 = getMutex(link.id);
 381     SpinMutexLock l(&mtx1->mtx);
 382     if (mtx1->seq != link.seq)
 383       continue;
 384     pt->visited[link.id] = true;
 385     if (mtx1->nlink == 0)
 386       continue;
 387     pt->path[npath++] = link;
 388     pt->pending[npending++] = Link(kEndId);
 389     if (link.id == m->id)
 390       return Report(pt, lt, npath);  // Bingo!
 391     for (int li = 0; li < mtx1->nlink; li++) {
 392       Link *link1 = &mtx1->link[li];
 393       // Mutex *mtx2 = getMutex(link->id);
 394       // FIXME(dvyukov): fast seq check
 395       // FIXME(dvyukov): fast nlink != 0 check
 396       // FIXME(dvyukov): fast pending check?
 397       // FIXME(dvyukov): npending can be larger than kMaxMutex
 398       pt->pending[npending++] = *link1;
 399     }
 400   }
 401 }
 402
 403 void DD::Report(DDPhysicalThread *pt, DDLogicalThread *lt, int npath) {
 404   DDReport *rep = &pt->rep;
 405   rep->n = npath;
 406   for (int i = 0; i < npath; i++) {
 407     Link *link = &pt->path[i];
 408     Link *link0 = &pt->path[i ? i - 1 : npath - 1];
 409     rep->loop[i].thr_ctx = link->tid;
 410     rep->loop[i].mtx_ctx0 = link0->id;
 411     rep->loop[i].mtx_ctx1 = link->id;
 412     rep->loop[i].stk[0] = flags.second_deadlock_stack ? link->stk0 : 0;
 413     rep->loop[i].stk[1] = link->stk1;
 414   }
 415   pt->report_pending = true;
 416 }
 417
 418 DDReport *DD::GetReport(DDCallback *cb) {
 419   if (!cb->pt->report_pending)
 420     return 0;
 421   cb->pt->report_pending = false;
 422   return &cb->pt->rep;
 423 }
 424
 425 }  // namespace __sanitizer
 426 #endif  // #if SANITIZER_DEADLOCK_DETECTOR_VERSION == 2