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Diffstat (limited to 'src/runtime/lockrank.go')
| -rw-r--r-- | src/runtime/lockrank.go | 248 |
1 files changed, 248 insertions, 0 deletions
diff --git a/src/runtime/lockrank.go b/src/runtime/lockrank.go new file mode 100644 index 0000000..b3c01ba --- /dev/null +++ b/src/runtime/lockrank.go @@ -0,0 +1,248 @@ +// Copyright 2020 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// This file records the static ranks of the locks in the runtime. If a lock +// is not given a rank, then it is assumed to be a leaf lock, which means no other +// lock can be acquired while it is held. Therefore, leaf locks do not need to be +// given an explicit rank. We list all of the architecture-independent leaf locks +// for documentation purposes, but don't list any of the architecture-dependent +// locks (which are all leaf locks). debugLock is ignored for ranking, since it is used +// when printing out lock ranking errors. +// +// lockInit(l *mutex, rank int) is used to set the rank of lock before it is used. +// If there is no clear place to initialize a lock, then the rank of a lock can be +// specified during the lock call itself via lockWithrank(l *mutex, rank int). +// +// Besides the static lock ranking (which is a total ordering of the locks), we +// also represent and enforce the actual partial order among the locks in the +// arcs[] array below. That is, if it is possible that lock B can be acquired when +// lock A is the previous acquired lock that is still held, then there should be +// an entry for A in arcs[B][]. We will currently fail not only if the total order +// (the lock ranking) is violated, but also if there is a missing entry in the +// partial order. + +package runtime + +type lockRank int + +// Constants representing the lock rank of the architecture-independent locks in +// the runtime. Locks with lower rank must be taken before locks with higher +// rank. +const ( + lockRankDummy lockRank = iota + + // Locks held above sched + lockRankSysmon + lockRankScavenge + lockRankForcegc + lockRankSweepWaiters + lockRankAssistQueue + lockRankCpuprof + lockRankSweep + + lockRankPollDesc + lockRankSched + lockRankDeadlock + lockRankPanic + lockRankAllg + lockRankAllp + + lockRankTimers // Multiple timers locked simultaneously in destroy() + lockRankItab + lockRankReflectOffs + lockRankHchan // Multiple hchans acquired in lock order in syncadjustsudogs() + lockRankFin + lockRankNotifyList + lockRankTraceBuf + lockRankTraceStrings + lockRankMspanSpecial + lockRankProf + lockRankGcBitsArenas + lockRankRoot + lockRankTrace + lockRankTraceStackTab + lockRankNetpollInit + + lockRankRwmutexW + lockRankRwmutexR + + lockRankSpanSetSpine + lockRankGscan + lockRankStackpool + lockRankStackLarge + lockRankDefer + lockRankSudog + + // Memory-related non-leaf locks + lockRankWbufSpans + lockRankMheap + lockRankMheapSpecial + + // Memory-related leaf locks + lockRankGlobalAlloc + + // Other leaf locks + lockRankGFree + // Generally, hchan must be acquired before gscan. But in one specific + // case (in syncadjustsudogs from markroot after the g has been suspended + // by suspendG), we allow gscan to be acquired, and then an hchan lock. To + // allow this case, we get this lockRankHchanLeaf rank in + // syncadjustsudogs(), rather than lockRankHchan. By using this special + // rank, we don't allow any further locks to be acquired other than more + // hchan locks. + lockRankHchanLeaf + + // Leaf locks with no dependencies, so these constants are not actually used anywhere. + // There are other architecture-dependent leaf locks as well. + lockRankNewmHandoff + lockRankDebugPtrmask + lockRankFaketimeState + lockRankTicks + lockRankRaceFini + lockRankPollCache + lockRankDebug +) + +// lockRankLeafRank is the rank of lock that does not have a declared rank, and hence is +// a leaf lock. +const lockRankLeafRank lockRank = 1000 + +// lockNames gives the names associated with each of the above ranks +var lockNames = []string{ + lockRankDummy: "", + + lockRankSysmon: "sysmon", + lockRankScavenge: "scavenge", + lockRankForcegc: "forcegc", + lockRankSweepWaiters: "sweepWaiters", + lockRankAssistQueue: "assistQueue", + lockRankCpuprof: "cpuprof", + lockRankSweep: "sweep", + + lockRankPollDesc: "pollDesc", + lockRankSched: "sched", + lockRankDeadlock: "deadlock", + lockRankPanic: "panic", + lockRankAllg: "allg", + lockRankAllp: "allp", + + lockRankTimers: "timers", + lockRankItab: "itab", + lockRankReflectOffs: "reflectOffs", + + lockRankHchan: "hchan", + lockRankFin: "fin", + lockRankNotifyList: "notifyList", + lockRankTraceBuf: "traceBuf", + lockRankTraceStrings: "traceStrings", + lockRankMspanSpecial: "mspanSpecial", + lockRankProf: "prof", + lockRankGcBitsArenas: "gcBitsArenas", + lockRankRoot: "root", + lockRankTrace: "trace", + lockRankTraceStackTab: "traceStackTab", + lockRankNetpollInit: "netpollInit", + + lockRankRwmutexW: "rwmutexW", + lockRankRwmutexR: "rwmutexR", + + lockRankSpanSetSpine: "spanSetSpine", + lockRankGscan: "gscan", + lockRankStackpool: "stackpool", + lockRankStackLarge: "stackLarge", + lockRankDefer: "defer", + lockRankSudog: "sudog", + + lockRankWbufSpans: "wbufSpans", + lockRankMheap: "mheap", + lockRankMheapSpecial: "mheapSpecial", + + lockRankGlobalAlloc: "globalAlloc.mutex", + + lockRankGFree: "gFree", + lockRankHchanLeaf: "hchanLeaf", + + lockRankNewmHandoff: "newmHandoff.lock", + lockRankDebugPtrmask: "debugPtrmask.lock", + lockRankFaketimeState: "faketimeState.lock", + lockRankTicks: "ticks.lock", + lockRankRaceFini: "raceFiniLock", + lockRankPollCache: "pollCache.lock", + lockRankDebug: "debugLock", +} + +func (rank lockRank) String() string { + if rank == 0 { + return "UNKNOWN" + } + if rank == lockRankLeafRank { + return "LEAF" + } + return lockNames[rank] +} + +// lockPartialOrder is a partial order among the various lock types, listing the +// immediate ordering that has actually been observed in the runtime. Each entry +// (which corresponds to a particular lock rank) specifies the list of locks +// that can already be held immediately "above" it. +// +// So, for example, the lockRankSched entry shows that all the locks preceding +// it in rank can actually be held. The allp lock shows that only the sysmon or +// sched lock can be held immediately above it when it is acquired. +var lockPartialOrder [][]lockRank = [][]lockRank{ + lockRankDummy: {}, + lockRankSysmon: {}, + lockRankScavenge: {lockRankSysmon}, + lockRankForcegc: {lockRankSysmon}, + lockRankSweepWaiters: {}, + lockRankAssistQueue: {}, + lockRankCpuprof: {}, + lockRankSweep: {}, + lockRankPollDesc: {}, + lockRankSched: {lockRankSysmon, lockRankScavenge, lockRankForcegc, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc}, + lockRankDeadlock: {lockRankDeadlock}, + lockRankPanic: {lockRankDeadlock}, + lockRankAllg: {lockRankSysmon, lockRankSched, lockRankPanic}, + lockRankAllp: {lockRankSysmon, lockRankSched}, + lockRankTimers: {lockRankSysmon, lockRankScavenge, lockRankSched, lockRankAllp, lockRankPollDesc, lockRankTimers}, + lockRankItab: {}, + lockRankReflectOffs: {lockRankItab}, + lockRankHchan: {lockRankScavenge, lockRankSweep, lockRankHchan}, + lockRankFin: {lockRankSysmon, lockRankScavenge, lockRankSched, lockRankAllg, lockRankTimers, lockRankHchan}, + lockRankNotifyList: {}, + lockRankTraceBuf: {lockRankSysmon, lockRankScavenge}, + lockRankTraceStrings: {lockRankTraceBuf}, + lockRankMspanSpecial: {lockRankSysmon, lockRankScavenge, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankItab, lockRankReflectOffs, lockRankHchan, lockRankNotifyList, lockRankTraceBuf, lockRankTraceStrings}, + lockRankProf: {lockRankSysmon, lockRankScavenge, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankItab, lockRankReflectOffs, lockRankNotifyList, lockRankTraceBuf, lockRankTraceStrings, lockRankHchan}, + lockRankGcBitsArenas: {lockRankSysmon, lockRankScavenge, lockRankAssistQueue, lockRankCpuprof, lockRankSched, lockRankAllg, lockRankTimers, lockRankItab, lockRankReflectOffs, lockRankNotifyList, lockRankTraceBuf, lockRankTraceStrings, lockRankHchan}, + lockRankRoot: {}, + lockRankTrace: {lockRankSysmon, lockRankScavenge, lockRankForcegc, lockRankAssistQueue, lockRankSched, lockRankHchan, lockRankTraceBuf, lockRankTraceStrings, lockRankRoot, lockRankSweep}, + lockRankTraceStackTab: {lockRankScavenge, lockRankSweepWaiters, lockRankAssistQueue, lockRankSweep, lockRankSched, lockRankAllg, lockRankTimers, lockRankHchan, lockRankFin, lockRankNotifyList, lockRankTraceBuf, lockRankTraceStrings, lockRankRoot, lockRankTrace}, + lockRankNetpollInit: {lockRankTimers}, + + lockRankRwmutexW: {}, + lockRankRwmutexR: {lockRankSysmon, lockRankRwmutexW}, + + lockRankSpanSetSpine: {lockRankSysmon, lockRankScavenge, lockRankForcegc, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankItab, lockRankReflectOffs, lockRankNotifyList, lockRankTraceBuf, lockRankTraceStrings, lockRankHchan}, + lockRankGscan: {lockRankSysmon, lockRankScavenge, lockRankForcegc, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankSched, lockRankTimers, lockRankItab, lockRankReflectOffs, lockRankHchan, lockRankFin, lockRankTraceBuf, lockRankTraceStrings, lockRankRoot, lockRankNotifyList, lockRankProf, lockRankGcBitsArenas, lockRankTrace, lockRankTraceStackTab, lockRankNetpollInit, lockRankSpanSetSpine}, + lockRankStackpool: {lockRankSysmon, lockRankScavenge, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankSched, lockRankPollDesc, lockRankTimers, lockRankItab, lockRankReflectOffs, lockRankHchan, lockRankFin, lockRankNotifyList, lockRankTraceBuf, lockRankTraceStrings, lockRankProf, lockRankGcBitsArenas, lockRankRoot, lockRankTrace, lockRankTraceStackTab, lockRankNetpollInit, lockRankRwmutexR, lockRankSpanSetSpine, lockRankGscan}, + lockRankStackLarge: {lockRankSysmon, lockRankAssistQueue, lockRankSched, lockRankItab, lockRankHchan, lockRankProf, lockRankGcBitsArenas, lockRankRoot, lockRankSpanSetSpine, lockRankGscan}, + lockRankDefer: {}, + lockRankSudog: {lockRankNotifyList, lockRankHchan}, + lockRankWbufSpans: {lockRankSysmon, lockRankScavenge, lockRankSweepWaiters, lockRankAssistQueue, lockRankSweep, lockRankSched, lockRankAllg, lockRankPollDesc, lockRankTimers, lockRankItab, lockRankReflectOffs, lockRankHchan, lockRankFin, lockRankNotifyList, lockRankTraceStrings, lockRankMspanSpecial, lockRankProf, lockRankRoot, lockRankGscan, lockRankDefer, lockRankSudog}, + lockRankMheap: {lockRankSysmon, lockRankScavenge, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankSched, lockRankAllg, lockRankAllp, lockRankFin, lockRankPollDesc, lockRankTimers, lockRankItab, lockRankReflectOffs, lockRankNotifyList, lockRankTraceBuf, lockRankTraceStrings, lockRankHchan, lockRankMspanSpecial, lockRankProf, lockRankGcBitsArenas, lockRankRoot, lockRankGscan, lockRankStackpool, lockRankStackLarge, lockRankDefer, lockRankSudog, lockRankWbufSpans, lockRankSpanSetSpine}, + lockRankMheapSpecial: {lockRankSysmon, lockRankScavenge, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankItab, lockRankReflectOffs, lockRankNotifyList, lockRankTraceBuf, lockRankTraceStrings, lockRankHchan}, + lockRankGlobalAlloc: {lockRankProf, lockRankSpanSetSpine, lockRankMheap, lockRankMheapSpecial}, + + lockRankGFree: {lockRankSched}, + lockRankHchanLeaf: {lockRankGscan, lockRankHchanLeaf}, + + lockRankNewmHandoff: {}, + lockRankDebugPtrmask: {}, + lockRankFaketimeState: {}, + lockRankTicks: {}, + lockRankRaceFini: {}, + lockRankPollCache: {}, + lockRankDebug: {}, +} |