diff --git a/src/internal/dag/alg.go b/src/internal/dag/alg.go
new file mode 100644
index 0000000000000000000000000000000000000000..88002797c02a04ce4f9dad32b8f91d9daf6c9b9b
--- /dev/null
+++ b/src/internal/dag/alg.go
@@ -0,0 +1,63 @@
+// Copyright 2022 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.
+
+package dag
+
+// Transpose reverses all edges in g.
+func (g *Graph) Transpose() {
+ old := g.edges
+
+ g.edges = make(map[string]map[string]bool)
+ for _, n := range g.Nodes {
+ g.edges[n] = make(map[string]bool)
+ }
+
+ for from, tos := range old {
+ for to := range tos {
+ g.edges[to][from] = true
+ }
+ }
+}
+
+// Topo returns a topological sort of g. This function is deterministic.
+func (g *Graph) Topo() []string {
+ topo := make([]string, 0, len(g.Nodes))
+ marks := make(map[string]bool)
+
+ var visit func(n string)
+ visit = func(n string) {
+ if marks[n] {
+ return
+ }
+ for _, to := range g.Edges(n) {
+ visit(to)
+ }
+ marks[n] = true
+ topo = append(topo, n)
+ }
+ for _, root := range g.Nodes {
+ visit(root)
+ }
+ for i, j := 0, len(topo)-1; i < j; i, j = i+1, j-1 {
+ topo[i], topo[j] = topo[j], topo[i]
+ }
+ return topo
+}
+
+// TransitiveReduction removes edges from g that are transitively
+// reachable. g must be transitively closed.
+func (g *Graph) TransitiveReduction() {
+ // For i -> j -> k, if i -> k exists, delete it.
+ for _, i := range g.Nodes {
+ for _, j := range g.Nodes {
+ if g.HasEdge(i, j) {
+ for _, k := range g.Nodes {
+ if g.HasEdge(j, k) {
+ g.DelEdge(i, k)
+ }
+ }
+ }
+ }
+ }
+}
diff --git a/src/internal/dag/alg_test.go b/src/internal/dag/alg_test.go
new file mode 100644
index 0000000000000000000000000000000000000000..e5ea8b6ab669b0e85c188f01dc74048ae8bd37f0
--- /dev/null
+++ b/src/internal/dag/alg_test.go
@@ -0,0 +1,46 @@
+// Copyright 2022 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.
+
+package dag
+
+import (
+ "reflect"
+ "strings"
+ "testing"
+)
+
+func TestTranspose(t *testing.T) {
+ g := mustParse(t, diamond)
+ g.Transpose()
+ wantEdges(t, g, "a->b a->c a->d b->d c->d")
+}
+
+func TestTopo(t *testing.T) {
+ g := mustParse(t, diamond)
+ got := g.Topo()
+ // "d" is the root, so it's first.
+ //
+ // "c" and "b" could be in either order, but Topo is
+ // deterministic in reverse node definition order.
+ //
+ // "a" is a leaf.
+ wantNodes := strings.Fields("d c b a")
+ if !reflect.DeepEqual(wantNodes, got) {
+ t.Fatalf("want topo sort %v, got %v", wantNodes, got)
+ }
+}
+
+func TestTransitiveReduction(t *testing.T) {
+ t.Run("diamond", func(t *testing.T) {
+ g := mustParse(t, diamond)
+ g.TransitiveReduction()
+ wantEdges(t, g, "b->a c->a d->b d->c")
+ })
+ t.Run("chain", func(t *testing.T) {
+ const chain = `NONE < a < b < c < d; a, d < e;`
+ g := mustParse(t, chain)
+ g.TransitiveReduction()
+ wantEdges(t, g, "e->d d->c c->b b->a")
+ })
+}
diff --git a/src/internal/dag/parse.go b/src/internal/dag/parse.go
index 1991772e39e7dc927c409cf1af06cd9a1533fcc9..9d5b918b1147cc45d99c83734172ca2256d2aaf5 100644
--- a/src/internal/dag/parse.go
+++ b/src/internal/dag/parse.go
@@ -71,6 +71,10 @@ func (g *Graph) AddEdge(from, to string) {
g.edges[from][to] = true
}
+func (g *Graph) DelEdge(from, to string) {
+ delete(g.edges[from], to)
+}
+
func (g *Graph) HasEdge(from, to string) bool {
return g.edges[from] != nil && g.edges[from][to]
}
diff --git a/src/runtime/lockrank.go b/src/runtime/lockrank.go
index 68cbee69fb43c6e3f6235e3a87bdb97962d97fda..1e83839120d1808fbd59ce981bebf86102ca5b28 100644
--- a/src/runtime/lockrank.go
+++ b/src/runtime/lockrank.go
@@ -1,162 +1,112 @@
-// 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.
+// Code generated by mklockrank.go; DO NOT EDIT.
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.
+// Constants representing the ranks of all non-leaf runtime locks, in rank order.
+// Locks with lower rank must be taken before locks with higher rank,
+// in addition to satisfying the partial order in lockPartialOrder.
+// A few ranks allow self-cycles, which are specified in lockPartialOrder.
const (
- lockRankDummy lockRank = iota
+ lockRankUnknown lockRank = iota
- // Locks held above sched
lockRankSysmon
- lockRankScavenge
- lockRankForcegc
lockRankSweepWaiters
lockRankAssistQueue
lockRankCpuprof
lockRankSweep
-
lockRankPollDesc
- lockRankSched
lockRankDeadlock
+ lockRankItab
+ lockRankNotifyList
+ lockRankRoot
+ lockRankRwmutexW
+ lockRankDefer
+ lockRankScavenge
+ lockRankForcegc
+ lockRankSched
lockRankAllg
lockRankAllp
-
- lockRankTimers // Multiple timers locked simultaneously in destroy()
- lockRankItab
+ lockRankTimers
lockRankReflectOffs
- lockRankHchan // Multiple hchans acquired in lock order in syncadjustsudogs()
+ lockRankHchan
lockRankTraceBuf
lockRankFin
- lockRankNotifyList
lockRankTraceStrings
lockRankMspanSpecial
lockRankProfInsert
lockRankProfBlock
lockRankProfMemActive
- lockRankProfMemFuture
lockRankGcBitsArenas
- lockRankRoot
+ lockRankSpanSetSpine
+ lockRankMheapSpecial
+ lockRankProfMemFuture
lockRankTrace
lockRankTraceStackTab
lockRankNetpollInit
-
- lockRankRwmutexW
lockRankRwmutexR
-
- lockRankSpanSetSpine
lockRankGscan
lockRankStackpool
lockRankStackLarge
- lockRankDefer
+ lockRankHchanLeaf
lockRankSudog
-
- // Memory-related non-leaf locks
lockRankWbufSpans
lockRankMheap
- lockRankMheapSpecial
-
- // Memory-related leaf locks
lockRankGlobalAlloc
-
- // Other leaf locks
-
- // 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
)
-// lockRankLeafRank is the rank of lock that does not have a declared rank, and hence is
-// a leaf lock.
+// 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
+// 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",
-
+ lockRankSysmon: "sysmon",
+ lockRankSweepWaiters: "sweepWaiters",
+ lockRankAssistQueue: "assistQueue",
+ lockRankCpuprof: "cpuprof",
+ lockRankSweep: "sweep",
+ lockRankPollDesc: "pollDesc",
+ lockRankDeadlock: "deadlock",
+ lockRankItab: "itab",
+ lockRankNotifyList: "notifyList",
+ lockRankRoot: "root",
+ lockRankRwmutexW: "rwmutexW",
+ lockRankDefer: "defer",
+ lockRankScavenge: "scavenge",
+ lockRankForcegc: "forcegc",
+ lockRankSched: "sched",
+ lockRankAllg: "allg",
+ lockRankAllp: "allp",
+ lockRankTimers: "timers",
+ lockRankReflectOffs: "reflectOffs",
lockRankHchan: "hchan",
lockRankTraceBuf: "traceBuf",
lockRankFin: "fin",
- lockRankNotifyList: "notifyList",
lockRankTraceStrings: "traceStrings",
lockRankMspanSpecial: "mspanSpecial",
lockRankProfInsert: "profInsert",
lockRankProfBlock: "profBlock",
lockRankProfMemActive: "profMemActive",
- lockRankProfMemFuture: "profMemFuture",
lockRankGcBitsArenas: "gcBitsArenas",
- lockRankRoot: "root",
+ lockRankSpanSetSpine: "spanSetSpine",
+ lockRankMheapSpecial: "mheapSpecial",
+ lockRankProfMemFuture: "profMemFuture",
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",
-
- lockRankHchanLeaf: "hchanLeaf",
- lockRankPanic: "panic",
+ lockRankRwmutexR: "rwmutexR",
+ lockRankGscan: "gscan",
+ lockRankStackpool: "stackpool",
+ lockRankStackLarge: "stackLarge",
+ lockRankHchanLeaf: "hchanLeaf",
+ lockRankSudog: "sudog",
+ lockRankWbufSpans: "wbufSpans",
+ lockRankMheap: "mheap",
+ lockRankGlobalAlloc: "globalAlloc",
+ lockRankPanic: "panic",
}
func (rank lockRank) String() string {
@@ -166,64 +116,60 @@ func (rank lockRank) String() string {
if rank == lockRankLeafRank {
return "LEAF"
}
+ if rank < 0 || int(rank) >= len(lockNames) {
+ return "BAD RANK"
+ }
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.
+// lockPartialOrder is the transitive closure of the lock rank graph.
+// An entry for rank X lists all of the ranks that can already be held
+// when rank X is acquired.
//
-// 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.
+// Lock ranks that allow self-cycles list themselves.
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},
+ lockRankDeadlock: {},
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},
- lockRankProfInsert: {lockRankSysmon, lockRankScavenge, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankItab, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankNotifyList, lockRankTraceStrings},
- lockRankProfBlock: {lockRankSysmon, lockRankScavenge, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankItab, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankNotifyList, lockRankTraceStrings},
- lockRankProfMemActive: {lockRankSysmon, lockRankScavenge, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankItab, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankNotifyList, lockRankTraceStrings},
- lockRankProfMemFuture: {lockRankSysmon, lockRankScavenge, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankItab, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankNotifyList, lockRankTraceStrings, lockRankProfMemActive},
- 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, lockRankProfInsert, lockRankProfBlock, lockRankProfMemActive, lockRankProfMemFuture, lockRankGcBitsArenas, lockRankRoot, lockRankTrace, lockRankTraceStackTab, lockRankNetpollInit, lockRankSpanSetSpine},
- lockRankStackpool: {lockRankSysmon, lockRankScavenge, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankSched, lockRankTimers, lockRankItab, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankFin, lockRankNotifyList, lockRankTraceStrings, lockRankProfInsert, lockRankProfBlock, lockRankProfMemActive, lockRankProfMemFuture, lockRankGcBitsArenas, lockRankRoot, lockRankTrace, lockRankTraceStackTab, lockRankNetpollInit, lockRankRwmutexR, lockRankSpanSetSpine, lockRankGscan},
- lockRankStackLarge: {lockRankSysmon, lockRankAssistQueue, lockRankSched, lockRankItab, lockRankHchan, lockRankProfInsert, lockRankProfBlock, lockRankProfMemActive, lockRankProfMemFuture, 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, lockRankProfInsert, lockRankProfBlock, lockRankProfMemActive, lockRankProfMemFuture, lockRankRoot, lockRankTrace, lockRankGscan, lockRankDefer, lockRankSudog},
- lockRankMheap: {lockRankSysmon, lockRankScavenge, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankItab, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankFin, lockRankNotifyList, lockRankTraceStrings, lockRankMspanSpecial, lockRankProfInsert, lockRankProfBlock, lockRankProfMemActive, lockRankProfMemFuture, lockRankGcBitsArenas, lockRankRoot, lockRankTrace, 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: {lockRankProfInsert, lockRankProfBlock, lockRankProfMemActive, lockRankProfMemFuture, lockRankSpanSetSpine, lockRankMheap, lockRankMheapSpecial},
-
- lockRankHchanLeaf: {lockRankGscan, lockRankHchanLeaf},
- lockRankPanic: {lockRankDeadlock}, // plus any other lock held on throw.
+ lockRankRwmutexW: {},
+ lockRankDefer: {},
+ lockRankScavenge: {lockRankSysmon},
+ lockRankForcegc: {lockRankSysmon},
+ lockRankSched: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankScavenge, lockRankForcegc},
+ lockRankAllg: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankScavenge, lockRankForcegc, lockRankSched},
+ lockRankAllp: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankScavenge, lockRankForcegc, lockRankSched},
+ lockRankTimers: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankScavenge, lockRankForcegc, lockRankSched, lockRankAllp, lockRankTimers},
+ lockRankReflectOffs: {lockRankItab},
+ lockRankHchan: {lockRankSysmon, lockRankSweep, lockRankScavenge, lockRankHchan},
+ lockRankTraceBuf: {lockRankSysmon, lockRankScavenge},
+ lockRankFin: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankItab, lockRankScavenge, lockRankForcegc, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf},
+ lockRankTraceStrings: {lockRankSysmon, lockRankScavenge, lockRankTraceBuf},
+ lockRankMspanSpecial: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankItab, lockRankNotifyList, lockRankScavenge, lockRankForcegc, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankTraceStrings},
+ lockRankProfInsert: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankItab, lockRankNotifyList, lockRankScavenge, lockRankForcegc, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankTraceStrings},
+ lockRankProfBlock: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankItab, lockRankNotifyList, lockRankScavenge, lockRankForcegc, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankTraceStrings},
+ lockRankProfMemActive: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankItab, lockRankNotifyList, lockRankScavenge, lockRankForcegc, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankTraceStrings},
+ lockRankGcBitsArenas: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankItab, lockRankNotifyList, lockRankScavenge, lockRankForcegc, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankTraceStrings},
+ lockRankSpanSetSpine: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankItab, lockRankNotifyList, lockRankScavenge, lockRankForcegc, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankTraceStrings},
+ lockRankMheapSpecial: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankItab, lockRankNotifyList, lockRankScavenge, lockRankForcegc, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankTraceStrings},
+ lockRankProfMemFuture: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankItab, lockRankNotifyList, lockRankScavenge, lockRankForcegc, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankTraceStrings, lockRankProfMemActive},
+ lockRankTrace: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankRoot, lockRankScavenge, lockRankForcegc, lockRankSched, lockRankHchan, lockRankTraceBuf, lockRankTraceStrings},
+ lockRankTraceStackTab: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankItab, lockRankNotifyList, lockRankRoot, lockRankScavenge, lockRankForcegc, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankFin, lockRankTraceStrings, lockRankTrace},
+ lockRankNetpollInit: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankScavenge, lockRankForcegc, lockRankSched, lockRankAllp, lockRankTimers},
+ lockRankRwmutexR: {lockRankSysmon, lockRankRwmutexW},
+ lockRankGscan: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankItab, lockRankNotifyList, lockRankRoot, lockRankScavenge, lockRankForcegc, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankFin, lockRankTraceStrings, lockRankProfInsert, lockRankProfBlock, lockRankProfMemActive, lockRankGcBitsArenas, lockRankSpanSetSpine, lockRankProfMemFuture, lockRankTrace, lockRankTraceStackTab, lockRankNetpollInit},
+ lockRankStackpool: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankItab, lockRankNotifyList, lockRankRoot, lockRankRwmutexW, lockRankScavenge, lockRankForcegc, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankFin, lockRankTraceStrings, lockRankProfInsert, lockRankProfBlock, lockRankProfMemActive, lockRankGcBitsArenas, lockRankSpanSetSpine, lockRankProfMemFuture, lockRankTrace, lockRankTraceStackTab, lockRankNetpollInit, lockRankRwmutexR, lockRankGscan},
+ lockRankStackLarge: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankItab, lockRankNotifyList, lockRankRoot, lockRankScavenge, lockRankForcegc, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankFin, lockRankTraceStrings, lockRankProfInsert, lockRankProfBlock, lockRankProfMemActive, lockRankGcBitsArenas, lockRankSpanSetSpine, lockRankProfMemFuture, lockRankTrace, lockRankTraceStackTab, lockRankNetpollInit, lockRankGscan},
+ lockRankHchanLeaf: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankItab, lockRankNotifyList, lockRankRoot, lockRankScavenge, lockRankForcegc, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankFin, lockRankTraceStrings, lockRankProfInsert, lockRankProfBlock, lockRankProfMemActive, lockRankGcBitsArenas, lockRankSpanSetSpine, lockRankProfMemFuture, lockRankTrace, lockRankTraceStackTab, lockRankNetpollInit, lockRankGscan, lockRankHchanLeaf},
+ lockRankSudog: {lockRankSysmon, lockRankSweep, lockRankNotifyList, lockRankScavenge, lockRankHchan},
+ lockRankWbufSpans: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankItab, lockRankNotifyList, lockRankRoot, lockRankDefer, lockRankScavenge, lockRankForcegc, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankFin, lockRankTraceStrings, lockRankMspanSpecial, lockRankProfInsert, lockRankProfBlock, lockRankProfMemActive, lockRankGcBitsArenas, lockRankSpanSetSpine, lockRankProfMemFuture, lockRankTrace, lockRankTraceStackTab, lockRankNetpollInit, lockRankGscan, lockRankSudog},
+ lockRankMheap: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankItab, lockRankNotifyList, lockRankRoot, lockRankRwmutexW, lockRankDefer, lockRankScavenge, lockRankForcegc, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankFin, lockRankTraceStrings, lockRankMspanSpecial, lockRankProfInsert, lockRankProfBlock, lockRankProfMemActive, lockRankGcBitsArenas, lockRankSpanSetSpine, lockRankProfMemFuture, lockRankTrace, lockRankTraceStackTab, lockRankNetpollInit, lockRankRwmutexR, lockRankGscan, lockRankStackpool, lockRankStackLarge, lockRankSudog, lockRankWbufSpans},
+ lockRankGlobalAlloc: {lockRankSysmon, lockRankSweepWaiters, lockRankAssistQueue, lockRankCpuprof, lockRankSweep, lockRankPollDesc, lockRankItab, lockRankNotifyList, lockRankRoot, lockRankRwmutexW, lockRankDefer, lockRankScavenge, lockRankForcegc, lockRankSched, lockRankAllg, lockRankAllp, lockRankTimers, lockRankReflectOffs, lockRankHchan, lockRankTraceBuf, lockRankFin, lockRankTraceStrings, lockRankMspanSpecial, lockRankProfInsert, lockRankProfBlock, lockRankProfMemActive, lockRankGcBitsArenas, lockRankSpanSetSpine, lockRankMheapSpecial, lockRankProfMemFuture, lockRankTrace, lockRankTraceStackTab, lockRankNetpollInit, lockRankRwmutexR, lockRankGscan, lockRankStackpool, lockRankStackLarge, lockRankSudog, lockRankWbufSpans, lockRankMheap},
+ lockRankPanic: {lockRankDeadlock},
}
diff --git a/src/runtime/lockrank_on.go b/src/runtime/lockrank_on.go
index a170569d6e2a983d5528d59af2c3f3cda2da4a1b..23adad7660dc6da4113a074fd9543e0efcb67da1 100644
--- a/src/runtime/lockrank_on.go
+++ b/src/runtime/lockrank_on.go
@@ -24,6 +24,9 @@ type lockRankStruct struct {
pad int
}
+// lockInit(l *mutex, rank int) sets 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).
func lockInit(l *mutex, rank lockRank) {
l.rank = rank
}
diff --git a/src/runtime/lockrank_test.go b/src/runtime/lockrank_test.go
index 4b2fc0eaeeaa67cb3a3ec1285032609bfce518cb..a7b1b8df7cde26e5724ddbdb53ba41f2f5d68d93 100644
--- a/src/runtime/lockrank_test.go
+++ b/src/runtime/lockrank_test.go
@@ -1,41 +1,29 @@
-// Copyright 2021 The Go Authors. All rights reserved.
+// Copyright 2022 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.
package runtime_test
import (
- . "runtime"
+ "bytes"
+ "internal/testenv"
+ "os"
+ "os/exec"
"testing"
)
-// Check that the partial order in lockPartialOrder fits within the total order
-// determined by the order of the lockRank constants.
-func TestLockRankPartialOrder(t *testing.T) {
- for r, list := range LockPartialOrder {
- rank := LockRank(r)
- for _, e := range list {
- entry := LockRank(e)
- if entry > rank {
- t.Errorf("lockPartialOrder row %v entry %v is inconsistent with total lock ranking order", rank, entry)
- }
- }
+// Test that the generated code for the lock rank graph is up-to-date.
+func TestLockRankGenerated(t *testing.T) {
+ testenv.MustHaveGoRun(t)
+ want, err := testenv.CleanCmdEnv(exec.Command(testenv.GoToolPath(t), "run", "mklockrank.go")).CombinedOutput()
+ if err != nil {
+ t.Fatal(err)
}
-}
-
-// Verify that partial order lists are kept sorted. This is a purely cosemetic
-// check to make manual reviews simpler. It does not affect correctness, unlike
-// the above test.
-func TestLockRankPartialOrderSortedEntries(t *testing.T) {
- for r, list := range LockPartialOrder {
- rank := LockRank(r)
- var prev LockRank
- for _, e := range list {
- entry := LockRank(e)
- if entry <= prev {
- t.Errorf("Partial order for rank %v out of order: %v <= %v in %v", rank, entry, prev, list)
- }
- prev = entry
- }
+ got, err := os.ReadFile("lockrank.go")
+ if err != nil {
+ t.Fatal(err)
+ }
+ if !bytes.Equal(want, got) {
+ t.Fatalf("lockrank.go is out of date. Please run go generate.")
}
}
diff --git a/src/runtime/mklockrank.go b/src/runtime/mklockrank.go
new file mode 100644
index 0000000000000000000000000000000000000000..9cb51bedcaec06dd06c59000385a6a380c977f4f
--- /dev/null
+++ b/src/runtime/mklockrank.go
@@ -0,0 +1,240 @@
+// Copyright 2022 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.
+
+//go:build ignore
+
+// mklockrank records the static rank graph of the locks in the
+// runtime and generates the rank checking structures in lockrank.go.
+package main
+
+import (
+ "bytes"
+ "flag"
+ "fmt"
+ "go/format"
+ "internal/dag"
+ "io"
+ "log"
+ "os"
+ "strings"
+)
+
+// ranks describes the lock rank graph. See "go doc internal/dag" for
+// the syntax.
+//
+// "a < b" means a must be acquired before b if both are held
+// (or, if b is held, a cannot be acquired).
+//
+// "NONE < a" means no locks may be held when a is acquired.
+//
+// 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.
+//
+// TODO: It's often hard to correlate rank names to locks. Change
+// these to be more consistent with the locks they label.
+const ranks = `
+NONE < sysmon, sweepWaiters, assistQueue, cpuprof, sweep, pollDesc, deadlock, itab, notifyList, root, rwmutexW, defer;
+sysmon < scavenge, forcegc;
+assistQueue, cpuprof, forcegc, pollDesc, scavenge, sweep, sweepWaiters < sched;
+sched < allg, allp;
+allp < timers;
+itab < reflectOffs;
+scavenge, sweep < hchan;
+scavenge < traceBuf;
+allg, hchan, reflectOffs, timers, traceBuf < fin;
+traceBuf < traceStrings;
+allg, hchan, notifyList, reflectOffs, timers, traceStrings < mspanSpecial, profInsert, profBlock, profMemActive, gcBitsArenas, spanSetSpine, mheapSpecial;
+profMemActive < profMemFuture;
+hchan, root, sched, traceStrings < trace;
+fin, notifyList, trace < traceStackTab;
+timers < netpollInit;
+rwmutexW, sysmon < rwmutexR;
+gcBitsArenas, netpollInit, profBlock, profInsert, profMemFuture, spanSetSpine, traceStackTab < gscan;
+gscan, rwmutexR < stackpool;
+gscan < stackLarge;
+
+# 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 use this hchanLeaf rank in syncadjustsudogs(),
+# rather than hchan. By using this special rank, we don't allow any further
+# locks to be acquired other than more hchan locks.
+gscan < hchanLeaf;
+
+hchan, notifyList < sudog;
+defer, gscan, mspanSpecial, sudog < wbufSpans;
+stackLarge, stackpool, wbufSpans < mheap;
+mheap, mheapSpecial < globalAlloc;
+
+# panic is handled specially. It is implicitly below all other locks.
+deadlock < panic;
+`
+
+// cyclicRanks lists lock ranks that allow multiple locks of the same
+// rank to be acquired simultaneously. The runtime enforces ordering
+// within these ranks using a separate mechanism.
+var cyclicRanks = map[string]bool{
+ // Multiple timers are locked simultaneously in destroy().
+ "timers": true,
+ // Multiple hchans are acquired in hchan.sortkey() order in
+ // select.
+ "hchan": true,
+ // Multiple hchanLeafs are acquired in hchan.sortkey() order in
+ // syncadjustsudogs().
+ "hchanLeaf": true,
+}
+
+func main() {
+ flagO := flag.String("o", "", "write to `file` instead of stdout")
+ flagDot := flag.Bool("dot", false, "emit graphviz output instead of Go")
+ flag.Parse()
+ if flag.NArg() != 0 {
+ fmt.Fprintf(os.Stderr, "too many arguments")
+ os.Exit(2)
+ }
+
+ g, err := dag.Parse(ranks)
+ if err != nil {
+ log.Fatal(err)
+ }
+
+ var out []byte
+ if *flagDot {
+ var b bytes.Buffer
+ g.TransitiveReduction()
+ // Add cyclic edges for visualization.
+ for k := range cyclicRanks {
+ g.AddEdge(k, k)
+ }
+ // Reverse the graph. It's much easier to read this as
+ // a "<" partial order than a ">" partial order. This
+ // ways, locks are acquired from the top going down
+ // and time moves forward over the edges instead of
+ // backward.
+ g.Transpose()
+ generateDot(&b, g)
+ out = b.Bytes()
+ } else {
+ var b bytes.Buffer
+ generateGo(&b, g)
+ out, err = format.Source(b.Bytes())
+ if err != nil {
+ log.Fatal(err)
+ }
+ }
+
+ if *flagO != "" {
+ err = os.WriteFile(*flagO, out, 0666)
+ } else {
+ _, err = os.Stdout.Write(out)
+ }
+ if err != nil {
+ log.Fatal(err)
+ }
+}
+
+func generateGo(w io.Writer, g *dag.Graph) {
+ fmt.Fprintf(w, `// Code generated by mklockrank.go; DO NOT EDIT.
+
+package runtime
+
+type lockRank int
+
+`)
+
+ // Create numeric ranks.
+ topo := g.Topo()
+ for i, j := 0, len(topo)-1; i < j; i, j = i+1, j-1 {
+ topo[i], topo[j] = topo[j], topo[i]
+ }
+ fmt.Fprintf(w, `
+// Constants representing the ranks of all non-leaf runtime locks, in rank order.
+// Locks with lower rank must be taken before locks with higher rank,
+// in addition to satisfying the partial order in lockPartialOrder.
+// A few ranks allow self-cycles, which are specified in lockPartialOrder.
+const (
+ lockRankUnknown lockRank = iota
+
+`)
+ for _, rank := range topo {
+ fmt.Fprintf(w, "\t%s\n", cname(rank))
+ }
+ fmt.Fprintf(w, `)
+
+// lockRankLeafRank is the rank of lock that does not have a declared rank,
+// and hence is a leaf lock.
+const lockRankLeafRank lockRank = 1000
+`)
+
+ // Create string table.
+ fmt.Fprintf(w, `
+// lockNames gives the names associated with each of the above ranks.
+var lockNames = []string{
+`)
+ for _, rank := range topo {
+ fmt.Fprintf(w, "\t%s: %q,\n", cname(rank), rank)
+ }
+ fmt.Fprintf(w, `}
+
+func (rank lockRank) String() string {
+ if rank == 0 {
+ return "UNKNOWN"
+ }
+ if rank == lockRankLeafRank {
+ return "LEAF"
+ }
+ if rank < 0 || int(rank) >= len(lockNames) {
+ return "BAD RANK"
+ }
+ return lockNames[rank]
+}
+`)
+
+ // Create partial order structure.
+ fmt.Fprintf(w, `
+// lockPartialOrder is the transitive closure of the lock rank graph.
+// An entry for rank X lists all of the ranks that can already be held
+// when rank X is acquired.
+//
+// Lock ranks that allow self-cycles list themselves.
+var lockPartialOrder [][]lockRank = [][]lockRank{
+`)
+ for _, rank := range topo {
+ list := []string{}
+ for _, before := range g.Edges(rank) {
+ list = append(list, cname(before))
+ }
+ if cyclicRanks[rank] {
+ list = append(list, cname(rank))
+ }
+
+ fmt.Fprintf(w, "\t%s: {%s},\n", cname(rank), strings.Join(list, ", "))
+ }
+ fmt.Fprintf(w, "}\n")
+}
+
+// cname returns the Go const name for the given lock rank label.
+func cname(label string) string {
+ return "lockRank" + strings.ToUpper(label[:1]) + label[1:]
+}
+
+// generateDot emits a Graphviz dot representation of g to w.
+func generateDot(w io.Writer, g *dag.Graph) {
+ fmt.Fprintf(w, "digraph g {\n")
+
+ // Define all nodes.
+ for _, node := range g.Nodes {
+ fmt.Fprintf(w, "%q;\n", node)
+ }
+
+ // Create edges.
+ for _, node := range g.Nodes {
+ for _, to := range g.Edges(node) {
+ fmt.Fprintf(w, "%q -> %q;\n", node, to)
+ }
+ }
+
+ fmt.Fprintf(w, "}\n")
+}
diff --git a/src/runtime/runtime.go b/src/runtime/runtime.go
index 2cf93abefa9150dc433d750a643c45859a822317..e9fd56b46d24fe96073f20a40fe96d2f5fe22a7e 100644
--- a/src/runtime/runtime.go
+++ b/src/runtime/runtime.go
@@ -12,6 +12,7 @@ import (
//go:generate go run wincallback.go
//go:generate go run mkduff.go
//go:generate go run mkfastlog2table.go
+//go:generate go run mklockrank.go -o lockrank.go
var ticks ticksType