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// 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
lockRankAllg
lockRankAllp
lockRankTimers // Multiple timers locked simultaneously in destroy()
lockRankItab
lockRankReflectOffs
lockRankHchan // Multiple hchans acquired in lock order in syncadjustsudogs()
lockRankTraceBuf
lockRankFin
lockRankNotifyList
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
lockRankPageAllocScav
// 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
lockRankPanic
// 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",
lockRankAllg: "allg",
lockRankAllp: "allp",
lockRankTimers: "timers",
lockRankItab: "itab",
lockRankReflectOffs: "reflectOffs",
lockRankHchan: "hchan",
lockRankTraceBuf: "traceBuf",
lockRankFin: "fin",
lockRankNotifyList: "notifyList",
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",
lockRankPageAllocScav: "pageAlloc.scav.lock",
lockRankGFree: "gFree",
lockRankHchanLeaf: "hchanLeaf",
lockRankPanic: "panic",
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},
lockRankAllg: {lockRankSysmon, lockRankSched},
lockRankAllp: {lockRankSysmon, lockRankSched},
lockRankTimers: {lockRankSysmon, lockRankScavenge, lockRankPollDesc, lockRankSched, lockRankAllp, lockRankTimers},
lockRankItab: {},
lockRankReflectOffs: {lockRankItab},
lockRankHchan: {lockRankScavenge, lockRankSweep, lockRankHchan},
lockRankTraceBuf: {lockRankSysmon, lockRankScavenge},
lockRankFin: {lockRankSysmon, lockRankScavenge, lockRankSched, lockRankAllg, lockRankTimers, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf},
lockRankNotifyList: {},
lockRankTraceStrings: {lockRankTraceBuf},
lockRankMspanSpecial: {lockRankSysmon, lockRankScavenge, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankItab, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankNotifyList, lockRankTraceStrings},
lockRankProf: {lockRankSysmon, lockRankScavenge, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankItab, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankNotifyList, lockRankTraceStrings},
lockRankGcBitsArenas: {lockRankSysmon, lockRankScavenge, lockRankAssistQueue, lockRankCpuprof, lockRankSched, lockRankAllg, lockRankTimers, lockRankItab, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankNotifyList, lockRankTraceStrings},
lockRankRoot: {},
lockRankTrace: {lockRankSysmon, lockRankScavenge, lockRankForcegc, lockRankAssistQueue, lockRankSweep, lockRankSched, lockRankHchan, lockRankTraceBuf, lockRankTraceStrings, lockRankRoot},
lockRankTraceStackTab: {lockRankScavenge, lockRankForcegc, lockRankSweepWaiters, lockRankAssistQueue, lockRankSweep, lockRankSched, lockRankAllg, lockRankTimers, lockRankHchan, lockRankTraceBuf, lockRankFin, lockRankNotifyList, lockRankTraceStrings, lockRankRoot, lockRankTrace},
lockRankNetpollInit: {lockRankTimers},
lockRankRwmutexW: {},
lockRankRwmutexR: {lockRankSysmon, lockRankRwmutexW},
lockRankSpanSetSpine: {lockRankSysmon, lockRankScavenge, lockRankForcegc, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankItab, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankNotifyList, lockRankTraceStrings},
lockRankGscan: {lockRankSysmon, lockRankScavenge, lockRankForcegc, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankSched, lockRankTimers, lockRankItab, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankFin, lockRankNotifyList, lockRankTraceStrings, lockRankProf, lockRankGcBitsArenas, lockRankRoot, lockRankTrace, lockRankTraceStackTab, lockRankNetpollInit, lockRankSpanSetSpine},
lockRankStackpool: {lockRankSysmon, lockRankScavenge, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankSched, lockRankTimers, lockRankItab, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankFin, lockRankNotifyList, lockRankTraceStrings, lockRankProf, lockRankGcBitsArenas, lockRankRoot, lockRankTrace, lockRankTraceStackTab, lockRankNetpollInit, lockRankRwmutexR, lockRankSpanSetSpine, lockRankGscan},
lockRankStackLarge: {lockRankSysmon, lockRankAssistQueue, lockRankSched, lockRankItab, lockRankHchan, lockRankProf, lockRankGcBitsArenas, lockRankRoot, lockRankSpanSetSpine, lockRankGscan},
lockRankDefer: {},
lockRankSudog: {lockRankHchan, lockRankNotifyList},
lockRankWbufSpans: {lockRankSysmon, lockRankScavenge, lockRankSweepWaiters, lockRankAssistQueue, lockRankSweep, lockRankPollDesc, lockRankSched, lockRankAllg, lockRankTimers, lockRankItab, lockRankReflectOffs, lockRankHchan, lockRankFin, lockRankNotifyList, lockRankTraceStrings, lockRankMspanSpecial, lockRankProf, lockRankRoot, lockRankGscan, lockRankDefer, lockRankSudog},
lockRankMheap: {lockRankSysmon, lockRankScavenge, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankItab, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankFin, lockRankNotifyList, lockRankTraceStrings, lockRankMspanSpecial, lockRankProf, lockRankGcBitsArenas, lockRankRoot, lockRankSpanSetSpine, lockRankGscan, lockRankStackpool, lockRankStackLarge, lockRankDefer, lockRankSudog, lockRankWbufSpans},
lockRankMheapSpecial: {lockRankSysmon, lockRankScavenge, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankItab, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankNotifyList, lockRankTraceStrings},
lockRankGlobalAlloc: {lockRankProf, lockRankSpanSetSpine, lockRankMheap, lockRankMheapSpecial},
lockRankPageAllocScav: {lockRankMheap},
lockRankGFree: {lockRankSched},
lockRankHchanLeaf: {lockRankGscan, lockRankHchanLeaf},
lockRankPanic: {lockRankDeadlock}, // plus any other lock held on throw.
lockRankNewmHandoff: {},
lockRankDebugPtrmask: {},
lockRankFaketimeState: {},
lockRankTicks: {},
lockRankRaceFini: {},
lockRankPollCache: {},
lockRankDebug: {},
}
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