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
21namespace __sanitizer {
22
23typedef TwoLevelBitVector<> DDBV; // DeadlockDetector's bit vector.
24
25struct DDPhysicalThread {
26};
27
28struct DDLogicalThread {
29 u64 ctx;
30 DeadlockDetectorTLS<DDBV> dd;
31 DDReport rep;
32 bool report_pending;
33};
34
35struct 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
61DDetector *DDetector::Create(const DDFlags *flags) {
62 (void)flags;
63 void *mem = MmapOrDie(size: sizeof(DD), mem_type: "deadlock detector");
64 return new(mem) DD(flags);
65}
66
67DD::DD(const DDFlags *flags)
68 : flags(*flags) {
69 dd.clear();
70}
71
72DDPhysicalThread* DD::CreatePhysicalThread() {
73 return nullptr;
74}
75
76void DD::DestroyPhysicalThread(DDPhysicalThread *pt) {
77}
78
79DDLogicalThread* DD::CreateLogicalThread(u64 ctx) {
80 DDLogicalThread *lt = (DDLogicalThread*)InternalAlloc(size: sizeof(*lt));
81 lt->ctx = ctx;
82 lt->dd.clear();
83 lt->report_pending = false;
84 return lt;
85}
86
87void DD::DestroyLogicalThread(DDLogicalThread *lt) {
88 lt->~DDLogicalThread();
89 InternalFree(p: lt);
90}
91
92void DD::MutexInit(DDCallback *cb, DDMutex *m) {
93 m->id = 0;
94 m->stk = cb->Unwind();
95}
96
97void DD::MutexEnsureID(DDLogicalThread *lt, DDMutex *m) {
98 if (!dd.nodeBelongsToCurrentEpoch(node: m->id))
99 m->id = dd.newNode(data: reinterpret_cast<uptr>(m));
100 dd.ensureCurrentEpoch(dtls: &lt->dd);
101}
102
103void 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(dtls: &lt->dd, cur_node: m->id)) return; // We already have all edges.
108 SpinMutexLock lk(&mtx);
109 MutexEnsureID(lt, m);
110 if (dd.isHeld(dtls: &lt->dd, node: m->id))
111 return; // FIXME: allow this only for recursive locks.
112 if (dd.onLockBefore(dtls: &lt->dd, cur_node: m->id)) {
113 // Actually add this edge now so that we have all the stack traces.
114 dd.addEdges(dtls: &lt->dd, cur_node: m->id, stk: cb->Unwind(), unique_tid: cb->UniqueTid());
115 ReportDeadlock(cb, m);
116 }
117}
118
119void DD::ReportDeadlock(DDCallback *cb, DDMutex *m) {
120 DDLogicalThread *lt = cb->lt;
121 uptr path[20];
122 uptr len = dd.findPathToLock(dtls: &lt->dd, cur_node: m->id, path, ARRAY_SIZE(path));
123 if (len == 0U) {
124 // A cycle of 20+ locks? Well, that's a bit odd...
125 Printf(format: "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>(a: len, b: 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(node: from);
137 DDMutex *m1 = (DDMutex*)dd.getData(node: to);
138
139 u32 stk_from = 0, stk_to = 0;
140 int unique_tid = 0;
141 dd.findEdge(from_node: from, to_node: to, stk_from: &stk_from, stk_to: &stk_to, unique_tid: &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
152void 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(dtls: &lt->dd, node: m->id, stk))
159 return;
160 if (dd.onLockFast(dtls: &lt->dd, node: 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(dtls: &lt->dd, cur_node: m->id, stk: stk ? stk : cb->Unwind(), unique_tid: cb->UniqueTid());
169 dd.onLockAfter(dtls: &lt->dd, cur_node: m->id, stk);
170}
171
172void DD::MutexBeforeUnlock(DDCallback *cb, DDMutex *m, bool wlock) {
173 // Printf("T%p MutexUnLock: %zx\n", cb->lt, m->id);
174 dd.onUnlock(dtls: &cb->lt->dd, node: m->id);
175}
176
177void DD::MutexDestroy(DDCallback *cb,
178 DDMutex *m) {
179 if (!m->id) return;
180 SpinMutexLock lk(&mtx);
181 if (dd.nodeBelongsToCurrentEpoch(node: m->id))
182 dd.removeNode(node: m->id);
183 m->id = 0;
184}
185
186DDReport *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
195

source code of compiler-rt/lib/sanitizer_common/sanitizer_deadlock_detector1.cpp