1 //===-- sanitizer_deadlock_detector1.cc -----------------------------------===//
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
7 //===----------------------------------------------------------------------===//
9 // Deadlock detector implementation based on NxN adjacency bit matrix.
11 //===----------------------------------------------------------------------===//
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"
19 #if SANITIZER_DEADLOCK_DETECTOR_VERSION == 1
21 namespace __sanitizer {
23 typedef TwoLevelBitVector<> DDBV; // DeadlockDetector's bit vector.
25 struct DDPhysicalThread {
28 struct DDLogicalThread {
30 DeadlockDetectorTLS<DDBV> dd;
35 struct DD : public DDetector {
37 DeadlockDetector<DDBV> dd;
40 explicit DD(const DDFlags *flags);
42 DDPhysicalThread *CreatePhysicalThread() override;
43 void DestroyPhysicalThread(DDPhysicalThread *pt) override;
45 DDLogicalThread *CreateLogicalThread(u64 ctx) override;
46 void DestroyLogicalThread(DDLogicalThread *lt) override;
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;
55 DDReport *GetReport(DDCallback *cb) override;
57 void MutexEnsureID(DDLogicalThread *lt, DDMutex *m);
58 void ReportDeadlock(DDCallback *cb, DDMutex *m);
61 DDetector *DDetector::Create(const DDFlags *flags) {
63 void *mem = MmapOrDie(sizeof(DD), "deadlock detector");
64 return new(mem) DD(flags);
67 DD::DD(const DDFlags *flags)
72 DDPhysicalThread* DD::CreatePhysicalThread() {
76 void DD::DestroyPhysicalThread(DDPhysicalThread *pt) {
79 DDLogicalThread* DD::CreateLogicalThread(u64 ctx) {
80 DDLogicalThread *lt = (DDLogicalThread*)InternalAlloc(sizeof(*lt));
83 lt->report_pending = false;
87 void DD::DestroyLogicalThread(DDLogicalThread *lt) {
88 lt->~DDLogicalThread();
92 void DD::MutexInit(DDCallback *cb, DDMutex *m) {
94 m->stk = cb->Unwind();
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(<->dd);
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(<->dd, m->id)) return; // We already have all edges.
108 SpinMutexLock lk(&mtx);
109 MutexEnsureID(lt, m);
110 if (dd.isHeld(<->dd, m->id))
111 return; // FIXME: allow this only for recursive locks.
112 if (dd.onLockBefore(<->dd, m->id)) {
113 // Actually add this edge now so that we have all the stack traces.
114 dd.addEdges(<->dd, m->id, cb->Unwind(), cb->UniqueTid());
115 ReportDeadlock(cb, m);
119 void DD::ReportDeadlock(DDCallback *cb, DDMutex *m) {
120 DDLogicalThread *lt = cb->lt;
122 uptr len = dd.findPathToLock(<->dd, m->id, path, ARRAY_SIZE(path));
124 // A cycle of 20+ locks? Well, that's a bit odd...
125 Printf("WARNING: too long mutex cycle found\n");
128 CHECK_EQ(m->id, path[0]);
129 lt->report_pending = true;
130 len = Min<uptr>(len, DDReport::kMaxLoopSize);
131 DDReport *rep = <->rep;
133 for (uptr i = 0; i < len; i++) {
135 uptr to = path[(i + 1) % len];
136 DDMutex *m0 = (DDMutex*)dd.getData(from);
137 DDMutex *m1 = (DDMutex*)dd.getData(to);
139 u32 stk_from = -1U, stk_to = -1U;
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,
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;
152 void DD::MutexAfterLock(DDCallback *cb, DDMutex *m, bool wlock, bool trylock) {
153 DDLogicalThread *lt = cb->lt;
155 if (flags.second_deadlock_stack)
157 // Printf("T%p MutexLock: %zx stk %u\n", lt, m->id, stk);
158 if (dd.onFirstLock(<->dd, m->id, stk))
160 if (dd.onLockFast(<->dd, m->id, stk))
163 SpinMutexLock lk(&mtx);
164 MutexEnsureID(lt, m);
165 if (wlock) // Only a recursive rlock may be held.
166 CHECK(!dd.isHeld(<->dd, m->id));
168 dd.addEdges(<->dd, m->id, stk ? stk : cb->Unwind(), cb->UniqueTid());
169 dd.onLockAfter(<->dd, m->id, stk);
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);
177 void DD::MutexDestroy(DDCallback *cb,
180 SpinMutexLock lk(&mtx);
181 if (dd.nodeBelongsToCurrentEpoch(m->id))
182 dd.removeNode(m->id);
186 DDReport *DD::GetReport(DDCallback *cb) {
187 if (!cb->lt->report_pending)
189 cb->lt->report_pending = false;
193 } // namespace __sanitizer
194 #endif // #if SANITIZER_DEADLOCK_DETECTOR_VERSION == 1