libsanitizer/sanitizer_common/sanitizer_deadlock_detector1.cpp

   1 //===-- sanitizer_deadlock_detector1.cpp ----------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // Deadlock detector implementation based on NxN adjacency bit matrix.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "sanitizer_deadlock_detector_interface.h"
  14 #include "sanitizer_deadlock_detector.h"
  15 #include "sanitizer_allocator_internal.h"
  16 #include "sanitizer_placement_new.h"
  17 #include "sanitizer_mutex.h"
  18
  19 #if SANITIZER_DEADLOCK_DETECTOR_VERSION == 1
  20
  21 namespace __sanitizer {
  22
  23 typedef TwoLevelBitVector<> DDBV;  // DeadlockDetector's bit vector.
  24
  25 struct DDPhysicalThread {
  26 };
  27
  28 struct DDLogicalThread {
  29   u64 ctx;
  30   DeadlockDetectorTLS<DDBV> dd;
  31   DDReport rep;
  32   bool report_pending;
  33 };
  34
  35 struct DD final : public DDetector {
  36   SpinMutex mtx;
  37   DeadlockDetector<DDBV> dd;
  38   DDFlags flags;
  39
  40   explicit DD(const DDFlags *flags);
  41
  42   DDPhysicalThread *CreatePhysicalThread() override;
  43   void DestroyPhysicalThread(DDPhysicalThread *pt) override;
  44
  45   DDLogicalThread *CreateLogicalThread(u64 ctx) override;
  46   void DestroyLogicalThread(DDLogicalThread *lt) override;
  47
  48   void MutexInit(DDCallback *cb, DDMutex *m) override;
  49   void MutexBeforeLock(DDCallback *cb, DDMutex *m, bool wlock) override;
  50   void MutexAfterLock(DDCallback *cb, DDMutex *m, bool wlock,
  51                       bool trylock) override;
  52   void MutexBeforeUnlock(DDCallback *cb, DDMutex *m, bool wlock) override;
  53   void MutexDestroy(DDCallback *cb, DDMutex *m) override;
  54
  55   DDReport *GetReport(DDCallback *cb) override;
  56
  57   void MutexEnsureID(DDLogicalThread *lt, DDMutex *m);
  58   void ReportDeadlock(DDCallback *cb, DDMutex *m);
  59 };
  60
  61 DDetector *DDetector::Create(const DDFlags *flags) {
  62   (void)flags;
  63   void *mem = MmapOrDie(sizeof(DD), "deadlock detector");
  64   return new(mem) DD(flags);
  65 }
  66
  67 DD::DD(const DDFlags *flags)
  68     : flags(*flags) {
  69   dd.clear();
  70 }
  71
  72 DDPhysicalThread* DD::CreatePhysicalThread() {
  73   return nullptr;
  74 }
  75
  76 void DD::DestroyPhysicalThread(DDPhysicalThread *pt) {
  77 }
  78
  79 DDLogicalThread* DD::CreateLogicalThread(u64 ctx) {
  80   DDLogicalThread *lt = (DDLogicalThread*)InternalAlloc(sizeof(*lt));
  81   lt->ctx = ctx;
  82   lt->dd.clear();
  83   lt->report_pending = false;
  84   return lt;
  85 }
  86
  87 void DD::DestroyLogicalThread(DDLogicalThread *lt) {
  88   lt->~DDLogicalThread();
  89   InternalFree(lt);
  90 }
  91
  92 void DD::MutexInit(DDCallback *cb, DDMutex *m) {
  93   m->id = 0;
  94   m->stk = cb->Unwind();
  95 }
  96
  97 void DD::MutexEnsureID(DDLogicalThread *lt, DDMutex *m) {
  98   if (!dd.nodeBelongsToCurrentEpoch(m->id))
  99     m->id = dd.newNode(reinterpret_cast<uptr>(m));
 100   dd.ensureCurrentEpoch(&lt->dd);
 101 }
 102
 103 void DD::MutexBeforeLock(DDCallback *cb,
 104     DDMutex *m, bool wlock) {
 105   DDLogicalThread *lt = cb->lt;
 106   if (lt->dd.empty()) return;  // This will be the first lock held by lt.
 107   if (dd.hasAllEdges(&lt->dd, m->id)) return;  // We already have all edges.
 108   SpinMutexLock lk(&mtx);
 109   MutexEnsureID(lt, m);
 110   if (dd.isHeld(&lt->dd, m->id))
 111     return;  // FIXME: allow this only for recursive locks.
 112   if (dd.onLockBefore(&lt->dd, m->id)) {
 113     // Actually add this edge now so that we have all the stack traces.
 114     dd.addEdges(&lt->dd, m->id, cb->Unwind(), cb->UniqueTid());
 115     ReportDeadlock(cb, m);
 116   }
 117 }
 118
 119 void DD::ReportDeadlock(DDCallback *cb, DDMutex *m) {
 120   DDLogicalThread *lt = cb->lt;
 121   uptr path[20];
 122   uptr len = dd.findPathToLock(&lt->dd, m->id, path, ARRAY_SIZE(path));
 123   if (len == 0U) {
 124     // A cycle of 20+ locks? Well, that's a bit odd...
 125     Printf("WARNING: too long mutex cycle found\n");
 126     return;
 127   }
 128   CHECK_EQ(m->id, path[0]);
 129   lt->report_pending = true;
 130   len = Min<uptr>(len, DDReport::kMaxLoopSize);
 131   DDReport *rep = &lt->rep;
 132   rep->n = len;
 133   for (uptr i = 0; i < len; i++) {
 134     uptr from = path[i];
 135     uptr to = path[(i + 1) % len];
 136     DDMutex *m0 = (DDMutex*)dd.getData(from);
 137     DDMutex *m1 = (DDMutex*)dd.getData(to);
 138
 139     u32 stk_from = 0, stk_to = 0;
 140     int unique_tid = 0;
 141     dd.findEdge(from, to, &stk_from, &stk_to, &unique_tid);
 142     // Printf("Edge: %zd=>%zd: %u/%u T%d\n", from, to, stk_from, stk_to,
 143     //    unique_tid);
 144     rep->loop[i].thr_ctx = unique_tid;
 145     rep->loop[i].mtx_ctx0 = m0->ctx;
 146     rep->loop[i].mtx_ctx1 = m1->ctx;
 147     rep->loop[i].stk[0] = stk_to;
 148     rep->loop[i].stk[1] = stk_from;
 149   }
 150 }
 151
 152 void DD::MutexAfterLock(DDCallback *cb, DDMutex *m, bool wlock, bool trylock) {
 153   DDLogicalThread *lt = cb->lt;
 154   u32 stk = 0;
 155   if (flags.second_deadlock_stack)
 156     stk = cb->Unwind();
 157   // Printf("T%p MutexLock:   %zx stk %u\n", lt, m->id, stk);
 158   if (dd.onFirstLock(&lt->dd, m->id, stk))
 159     return;
 160   if (dd.onLockFast(&lt->dd, m->id, stk))
 161     return;
 162
 163   SpinMutexLock lk(&mtx);
 164   MutexEnsureID(lt, m);
 165   if (wlock)  // Only a recursive rlock may be held.
 166     CHECK(!dd.isHeld(&lt->dd, m->id));
 167   if (!trylock)
 168     dd.addEdges(&lt->dd, m->id, stk ? stk : cb->Unwind(), cb->UniqueTid());
 169   dd.onLockAfter(&lt->dd, m->id, stk);
 170 }
 171
 172 void DD::MutexBeforeUnlock(DDCallback *cb, DDMutex *m, bool wlock) {
 173   // Printf("T%p MutexUnLock: %zx\n", cb->lt, m->id);
 174   dd.onUnlock(&cb->lt->dd, m->id);
 175 }
 176
 177 void DD::MutexDestroy(DDCallback *cb,
 178     DDMutex *m) {
 179   if (!m->id) return;
 180   SpinMutexLock lk(&mtx);
 181   if (dd.nodeBelongsToCurrentEpoch(m->id))
 182     dd.removeNode(m->id);
 183   m->id = 0;
 184 }
 185
 186 DDReport *DD::GetReport(DDCallback *cb) {
 187   if (!cb->lt->report_pending)
 188     return nullptr;
 189   cb->lt->report_pending = false;
 190   return &cb->lt->rep;
 191 }
 192
 193 } // namespace __sanitizer
 194 #endif // #if SANITIZER_DEADLOCK_DETECTOR_VERSION == 1