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 = 0;
 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) : flags(*flags) { free_id.reserve(1024); }
 122
 123 DDPhysicalThread* DD::CreatePhysicalThread() {
 124   DDPhysicalThread *pt = (DDPhysicalThread*)MmapOrDie(sizeof(DDPhysicalThread),
 125       "deadlock detector (physical thread)");
 126   return pt;
 127 }
 128
 129 void DD::DestroyPhysicalThread(DDPhysicalThread *pt) {
 130   pt->~DDPhysicalThread();
 131   UnmapOrDie(pt, sizeof(DDPhysicalThread));
 132 }
 133
 134 DDLogicalThread* DD::CreateLogicalThread(u64 ctx) {
 135   DDLogicalThread *lt = (DDLogicalThread*)InternalAlloc(
 136       sizeof(DDLogicalThread));
 137   lt->ctx = ctx;
 138   lt->nlocked = 0;
 139   return lt;
 140 }
 141
 142 void DD::DestroyLogicalThread(DDLogicalThread *lt) {
 143   lt->~DDLogicalThread();
 144   InternalFree(lt);
 145 }
 146
 147 void DD::MutexInit(DDCallback *cb, DDMutex *m) {
 148   VPrintf(2, "#%llu: DD::MutexInit(%p)\n", cb->lt->ctx, m);
 149   m->id = kNoId;
 150   m->recursion = 0;
 151   atomic_store(&m->owner, 0, memory_order_relaxed);
 152 }
 153
 154 Mutex *DD::getMutex(u32 id) {
 155   return &mutex[id / kL2Size][id % kL2Size];
 156 }
 157
 158 u32 DD::getMutexId(Mutex *m) {
 159   for (int i = 0; i < kL1Size; i++) {
 160     Mutex *tab = mutex[i];
 161     if (tab == 0)
 162       break;
 163     if (m >= tab && m < tab + kL2Size)
 164       return i * kL2Size + (m - tab);
 165   }
 166   return -1;
 167 }
 168
 169 u32 DD::allocateId(DDCallback *cb) {
 170   u32 id = -1;
 171   SpinMutexLock l(&mtx);
 172   if (free_id.size() > 0) {
 173     id = free_id.back();
 174     free_id.pop_back();
 175   } else {
 176     CHECK_LT(id_gen, kMaxMutex);
 177     if ((id_gen % kL2Size) == 0) {
 178       mutex[id_gen / kL2Size] = (Mutex*)MmapOrDie(kL2Size * sizeof(Mutex),
 179           "deadlock detector (mutex table)");
 180     }
 181     id = id_gen++;
 182   }
 183   CHECK_LE(id, kMaxMutex);
 184   VPrintf(3, "#%llu: DD::allocateId assign id %d\n", cb->lt->ctx, id);
 185   return id;
 186 }
 187
 188 void DD::MutexBeforeLock(DDCallback *cb, DDMutex *m, bool wlock) {
 189   VPrintf(2, "#%llu: DD::MutexBeforeLock(%p, wlock=%d) nlocked=%d\n",
 190       cb->lt->ctx, m, wlock, cb->lt->nlocked);
 191   DDPhysicalThread *pt = cb->pt;
 192   DDLogicalThread *lt = cb->lt;
 193
 194   uptr owner = atomic_load(&m->owner, memory_order_relaxed);
 195   if (owner == (uptr)cb->lt) {
 196     VPrintf(3, "#%llu: DD::MutexBeforeLock recursive\n",
 197         cb->lt->ctx);
 198     return;
 199   }
 200
 201   CHECK_LE(lt->nlocked, kMaxNesting);
 202
 203   // FIXME(dvyukov): don't allocate id if lt->nlocked == 0?
 204   if (m->id == kNoId)
 205     m->id = allocateId(cb);
 206
 207   ThreadMutex *tm = &lt->locked[lt->nlocked++];
 208   tm->id = m->id;
 209   if (flags.second_deadlock_stack)
 210     tm->stk = cb->Unwind();
 211   if (lt->nlocked == 1) {
 212     VPrintf(3, "#%llu: DD::MutexBeforeLock first mutex\n",
 213         cb->lt->ctx);
 214     return;
 215   }
 216
 217   bool added = false;
 218   Mutex *mtx = getMutex(m->id);
 219   for (int i = 0; i < lt->nlocked - 1; i++) {
 220     u32 id1 = lt->locked[i].id;
 221     u32 stk1 = lt->locked[i].stk;
 222     Mutex *mtx1 = getMutex(id1);
 223     SpinMutexLock l(&mtx1->mtx);
 224     if (mtx1->nlink == kMaxLink) {
 225       // FIXME(dvyukov): check stale links
 226       continue;
 227     }
 228     int li = 0;
 229     for (; li < mtx1->nlink; li++) {
 230       Link *link = &mtx1->link[li];
 231       if (link->id == m->id) {
 232         if (link->seq != mtx->seq) {
 233           link->seq = mtx->seq;
 234           link->tid = lt->ctx;
 235           link->stk0 = stk1;
 236           link->stk1 = cb->Unwind();
 237           added = true;
 238           VPrintf(3, "#%llu: DD::MutexBeforeLock added %d->%d link\n",
 239               cb->lt->ctx, getMutexId(mtx1), m->id);
 240         }
 241         break;
 242       }
 243     }
 244     if (li == mtx1->nlink) {
 245       // FIXME(dvyukov): check stale links
 246       Link *link = &mtx1->link[mtx1->nlink++];
 247       link->id = m->id;
 248       link->seq = mtx->seq;
 249       link->tid = lt->ctx;
 250       link->stk0 = stk1;
 251       link->stk1 = cb->Unwind();
 252       added = true;
 253       VPrintf(3, "#%llu: DD::MutexBeforeLock added %d->%d link\n",
 254           cb->lt->ctx, getMutexId(mtx1), m->id);
 255     }
 256   }
 257
 258   if (!added || mtx->nlink == 0) {
 259     VPrintf(3, "#%llu: DD::MutexBeforeLock don't check\n",
 260         cb->lt->ctx);
 261     return;
 262   }
 263
 264   CycleCheck(pt, lt, m);
 265 }
 266
 267 void DD::MutexAfterLock(DDCallback *cb, DDMutex *m, bool wlock,
 268     bool trylock) {
 269   VPrintf(2, "#%llu: DD::MutexAfterLock(%p, wlock=%d, try=%d) nlocked=%d\n",
 270       cb->lt->ctx, m, wlock, trylock, cb->lt->nlocked);
 271   DDLogicalThread *lt = cb->lt;
 272
 273   uptr owner = atomic_load(&m->owner, memory_order_relaxed);
 274   if (owner == (uptr)cb->lt) {
 275     VPrintf(3, "#%llu: DD::MutexAfterLock recursive\n", cb->lt->ctx);
 276     CHECK(wlock);
 277     m->recursion++;
 278     return;
 279   }
 280   CHECK_EQ(owner, 0);
 281   if (wlock) {
 282     VPrintf(3, "#%llu: DD::MutexAfterLock set owner\n", cb->lt->ctx);
 283     CHECK_EQ(m->recursion, 0);
 284     m->recursion = 1;
 285     atomic_store(&m->owner, (uptr)cb->lt, memory_order_relaxed);
 286   }
 287
 288   if (!trylock)
 289     return;
 290
 291   CHECK_LE(lt->nlocked, kMaxNesting);
 292   if (m->id == kNoId)
 293     m->id = allocateId(cb);
 294   ThreadMutex *tm = &lt->locked[lt->nlocked++];
 295   tm->id = m->id;
 296   if (flags.second_deadlock_stack)
 297     tm->stk = cb->Unwind();
 298 }
 299
 300 void DD::MutexBeforeUnlock(DDCallback *cb, DDMutex *m, bool wlock) {
 301   VPrintf(2, "#%llu: DD::MutexBeforeUnlock(%p, wlock=%d) nlocked=%d\n",
 302       cb->lt->ctx, m, wlock, cb->lt->nlocked);
 303   DDLogicalThread *lt = cb->lt;
 304
 305   uptr owner = atomic_load(&m->owner, memory_order_relaxed);
 306   if (owner == (uptr)cb->lt) {
 307     VPrintf(3, "#%llu: DD::MutexBeforeUnlock recursive\n", cb->lt->ctx);
 308     if (--m->recursion > 0)
 309       return;
 310     VPrintf(3, "#%llu: DD::MutexBeforeUnlock reset owner\n", cb->lt->ctx);
 311     atomic_store(&m->owner, 0, memory_order_relaxed);
 312   }
 313   CHECK_NE(m->id, kNoId);
 314   int last = lt->nlocked - 1;
 315   for (int i = last; i >= 0; i--) {
 316     if (cb->lt->locked[i].id == m->id) {
 317       lt->locked[i] = lt->locked[last];
 318       lt->nlocked--;
 319       break;
 320     }
 321   }
 322 }
 323
 324 void DD::MutexDestroy(DDCallback *cb, DDMutex *m) {
 325   VPrintf(2, "#%llu: DD::MutexDestroy(%p)\n",
 326       cb->lt->ctx, m);
 327   DDLogicalThread *lt = cb->lt;
 328
 329   if (m->id == kNoId)
 330     return;
 331
 332   // Remove the mutex from lt->locked if there.
 333   int last = lt->nlocked - 1;
 334   for (int i = last; i >= 0; i--) {
 335     if (lt->locked[i].id == m->id) {
 336       lt->locked[i] = lt->locked[last];
 337       lt->nlocked--;
 338       break;
 339     }
 340   }
 341
 342   // Clear and invalidate the mutex descriptor.
 343   {
 344     Mutex *mtx = getMutex(m->id);
 345     SpinMutexLock l(&mtx->mtx);
 346     mtx->seq++;
 347     mtx->nlink = 0;
 348   }
 349
 350   // Return id to cache.
 351   {
 352     SpinMutexLock l(&mtx);
 353     free_id.push_back(m->id);
 354   }
 355 }
 356
 357 void DD::CycleCheck(DDPhysicalThread *pt, DDLogicalThread *lt,
 358     DDMutex *m) {
 359   internal_memset(pt->visited, 0, sizeof(pt->visited));
 360   int npath = 0;
 361   int npending = 0;
 362   {
 363     Mutex *mtx = getMutex(m->id);
 364     SpinMutexLock l(&mtx->mtx);
 365     for (int li = 0; li < mtx->nlink; li++)
 366       pt->pending[npending++] = mtx->link[li];
 367   }
 368   while (npending > 0) {
 369     Link link = pt->pending[--npending];
 370     if (link.id == kEndId) {
 371       npath--;
 372       continue;
 373     }
 374     if (pt->visited[link.id])
 375       continue;
 376     Mutex *mtx1 = getMutex(link.id);
 377     SpinMutexLock l(&mtx1->mtx);
 378     if (mtx1->seq != link.seq)
 379       continue;
 380     pt->visited[link.id] = true;
 381     if (mtx1->nlink == 0)
 382       continue;
 383     pt->path[npath++] = link;
 384     pt->pending[npending++] = Link(kEndId);
 385     if (link.id == m->id)
 386       return Report(pt, lt, npath);  // Bingo!
 387     for (int li = 0; li < mtx1->nlink; li++) {
 388       Link *link1 = &mtx1->link[li];
 389       // Mutex *mtx2 = getMutex(link->id);
 390       // FIXME(dvyukov): fast seq check
 391       // FIXME(dvyukov): fast nlink != 0 check
 392       // FIXME(dvyukov): fast pending check?
 393       // FIXME(dvyukov): npending can be larger than kMaxMutex
 394       pt->pending[npending++] = *link1;
 395     }
 396   }
 397 }
 398
 399 void DD::Report(DDPhysicalThread *pt, DDLogicalThread *lt, int npath) {
 400   DDReport *rep = &pt->rep;
 401   rep->n = npath;
 402   for (int i = 0; i < npath; i++) {
 403     Link *link = &pt->path[i];
 404     Link *link0 = &pt->path[i ? i - 1 : npath - 1];
 405     rep->loop[i].thr_ctx = link->tid;
 406     rep->loop[i].mtx_ctx0 = link0->id;
 407     rep->loop[i].mtx_ctx1 = link->id;
 408     rep->loop[i].stk[0] = flags.second_deadlock_stack ? link->stk0 : 0;
 409     rep->loop[i].stk[1] = link->stk1;
 410   }
 411   pt->report_pending = true;
 412 }
 413
 414 DDReport *DD::GetReport(DDCallback *cb) {
 415   if (!cb->pt->report_pending)
 416     return 0;
 417   cb->pt->report_pending = false;
 418   return &cb->pt->rep;
 419 }
 420
 421 }  // namespace __sanitizer
 422 #endif  // #if SANITIZER_DEADLOCK_DETECTOR_VERSION == 2