[dev.unified] all: merge master (85d87b9) into dev.unifieddev.unified

Merge List:

+ 2022-08-04 85d87b9c75 all: update vendored golang.org/x dependencies for Go 1.20 development
+ 2022-08-04 fb1bfd4d37 all: remove pre-Go 1.17 workarounds
+ 2022-08-04 44ff9bff0c runtime: clean up panic and deadlock lock ranks
+ 2022-08-04 f42dc0de74 runtime: make the lock rank DAG make more sense
+ 2022-08-04 d29a0282e9 runtime: add mayAcquire annotation for finlock
+ 2022-08-04 c5be4ed7df runtime: add missing trace lock edges
+ 2022-08-04 2b8a9a484f runtime: generate the lock ranking from a DAG description
+ 2022-08-04 ddfd639408 runtime: delete unused lock ranks
+ 2022-08-04 426ea5702b internal/dag: add a Graph type and make node order deterministic
+ 2022-08-04 d37cc9a8cd go/build, internal/dag: lift DAG parser into an internal package
+ 2022-08-04 ab0a94c6d3 cmd/dist: require Go 1.17 for building Go
+ 2022-08-04 1e3c19f3fe runtime: support riscv64 SV57 mode
+ 2022-08-03 f28fa952b5 make.bat, make.rc: show bootstrap toolchain version
+ 2022-08-03 87384801dc cmd/asm: update package doc to describe "-p" option
+ 2022-08-03 c6a2dada0d net: disable TestIPv6WriteMsgUDPAddrPortTargetAddrIPVersion [sic] on DragonflyBSD
+ 2022-08-02 29b9a328d2 runtime: trivial replacements of g in remaining files
+ 2022-08-02 c647264619 runtime: trivial replacements of g in signal_unix.go
+ 2022-08-02 399f50c9d7 runtime: tricky replacements of g in traceback.go
+ 2022-08-02 4509e951ec runtime: tricky replacements of g in proc.go
+ 2022-08-02 4400238ec8 runtime: trivial replacements of _g_ in remaining files
+ 2022-08-02 5999a28de8 runtime: trivial replacements of _g_ in os files
+ 2022-08-02 0e18cf6d09 runtime: trivial replacements of _g_ in GC files
+ 2022-08-02 4358a53a97 runtime: trivial replacements of _g_ in proc.go
+ 2022-08-02 b486518964 runtime: tricky replacements of _g_ in os3_solaris.go
+ 2022-08-02 54a0ab3f7b runtime: tricky replacements of _g_ in os3_plan9.go
+ 2022-08-02 4240ff764b runtime: tricky replacements of _g_ in signal_windows.go
+ 2022-08-02 8666d89ca8 runtime: tricky replacements of _g_ in signal_unix.go
+ 2022-08-02 74cee276fe runtime: tricky replacements of _g_ in trace.go
+ 2022-08-02 222799fde6 runtime: tricky replacements of _g_ in mgc.go
+ 2022-08-02 e9d7f54a1a runtime: tricky replacements of _g_ in proc.go
+ 2022-08-02 5e8d261918 runtime: rename _p_ to pp
+ 2022-08-02 0ad2ec6596 runtime: clean up dopanic_m
+ 2022-08-02 7e952962df runtime: clean up canpanic
+ 2022-08-02 9dbc0f3556 runtime: fix outdated g.m comment in traceback.go
+ 2022-08-02 d723df76da internal/goversion: update Version to 1.20
+ 2022-08-02 1b7e71e8ae all: disable tests that fail on Alpine
+ 2022-08-01 f2a9f3e2e0 test: improve generic type assertion test
+ 2022-08-01 27038b70f8 cmd/compile: fix wrong dict pass condition for type assertions
+ 2022-08-01 e99f53fed9 doc: move Go 1.19 release notes to x/website
+ 2022-08-01 8b13a073a1 doc: mention removal of cmd/compile's -importmap and -installsuffix flags
+ 2022-08-01 e95fd4c238 doc/go1.19: fix typo: EM_LONGARCH -> EM_LOONGARCH
+ 2022-08-01 dee3efd9f8 doc/go1.19: fix a few links that were missing trailing slashes
+ 2022-07-30 f32519e5fb runtime: fix typos
+ 2022-07-29 9a2001a8cc cmd/dist: always pass -short=true with -quick
+ 2022-07-28 5c8ec89cb5 doc/go1.19: minor adjustments and links
+ 2022-07-28 417be37048 doc/go1.19: improve the loong64 release notes
+ 2022-07-28 027855e8d8 os/exec: add GODEBUG setting to opt out of ErrDot changes

Change-Id: Idc0fbe93978c0dff7600b90a2c3ecc067fd9f5f2

1 files changed, 22 insertions, 18 deletions

diff --git a/src/runtime/panic.go b/src/runtime/panic.go
index 121f2022a4..3783e3dede 100644
--- a/src/runtime/panic.go
+++ b/src/runtime/panic.go
@@ -1190,7 +1190,7 @@ func fatalpanic(msgs *_panic) {
 //
 //go:nowritebarrierrec
 func startpanic_m() bool {
-	_g_ := getg()
+	gp := getg()
 	if mheap_.cachealloc.size == 0 { // very early
 		print("runtime: panic before malloc heap initialized\n")
 	}
@@ -1198,18 +1198,18 @@ func startpanic_m() bool {
 	// could happen in a signal handler, or in a throw, or inside
 	// malloc itself. We want to catch if an allocation ever does
 	// happen (even if we're not in one of these situations).
-	_g_.m.mallocing++
+	gp.m.mallocing++
 
 	// If we're dying because of a bad lock count, set it to a
 	// good lock count so we don't recursively panic below.
-	if _g_.m.locks < 0 {
-		_g_.m.locks = 1
+	if gp.m.locks < 0 {
+		gp.m.locks = 1
 	}
 
-	switch _g_.m.dying {
+	switch gp.m.dying {
 	case 0:
 		// Setting dying >0 has the side-effect of disabling this G's writebuf.
-		_g_.m.dying = 1
+		gp.m.dying = 1
 		atomic.Xadd(&panicking, 1)
 		lock(&paniclk)
 		if debug.schedtrace > 0 || debug.scheddetail > 0 {
@@ -1220,13 +1220,13 @@ func startpanic_m() bool {
 	case 1:
 		// Something failed while panicking.
 		// Just print a stack trace and exit.
-		_g_.m.dying = 2
+		gp.m.dying = 2
 		print("panic during panic\n")
 		return false
 	case 2:
 		// This is a genuine bug in the runtime, we couldn't even
 		// print the stack trace successfully.
-		_g_.m.dying = 3
+		gp.m.dying = 3
 		print("stack trace unavailable\n")
 		exit(4)
 		fallthrough
@@ -1240,6 +1240,8 @@ func startpanic_m() bool {
 var didothers bool
 var deadlock mutex
 
+// gp is the crashing g running on this M, but may be a user G, while getg() is
+// always g0.
 func dopanic_m(gp *g, pc, sp uintptr) bool {
 	if gp.sig != 0 {
 		signame := signame(gp.sig)
@@ -1252,7 +1254,6 @@ func dopanic_m(gp *g, pc, sp uintptr) bool {
 	}
 
 	level, all, docrash := gotraceback()
-	_g_ := getg()
 	if level > 0 {
 		if gp != gp.m.curg {
 			all = true
@@ -1261,7 +1262,7 @@ func dopanic_m(gp *g, pc, sp uintptr) bool {
 			print("\n")
 			goroutineheader(gp)
 			traceback(pc, sp, 0, gp)
-		} else if level >= 2 || _g_.m.throwing >= throwTypeRuntime {
+		} else if level >= 2 || gp.m.throwing >= throwTypeRuntime {
 			print("\nruntime stack:\n")
 			traceback(pc, sp, 0, gp)
 		}
@@ -1290,29 +1291,32 @@ func dopanic_m(gp *g, pc, sp uintptr) bool {
 // panicking.
 //
 //go:nosplit
-func canpanic(gp *g) bool {
-	// Note that g is m->gsignal, different from gp.
-	// Note also that g->m can change at preemption, so m can go stale
-	// if this function ever makes a function call.
-	_g_ := getg()
-	mp := _g_.m
+func canpanic() bool {
+	gp := getg()
+	mp := acquirem()
 
 	// Is it okay for gp to panic instead of crashing the program?
 	// Yes, as long as it is running Go code, not runtime code,
 	// and not stuck in a system call.
-	if gp == nil || gp != mp.curg {
+	if gp != mp.curg {
+		releasem(mp)
 		return false
 	}
-	if mp.locks != 0 || mp.mallocing != 0 || mp.throwing != throwTypeNone || mp.preemptoff != "" || mp.dying != 0 {
+	// N.B. mp.locks != 1 instead of 0 to account for acquirem.
+	if mp.locks != 1 || mp.mallocing != 0 || mp.throwing != throwTypeNone || mp.preemptoff != "" || mp.dying != 0 {
+		releasem(mp)
 		return false
 	}
 	status := readgstatus(gp)
 	if status&^_Gscan != _Grunning || gp.syscallsp != 0 {
+		releasem(mp)
 		return false
 	}
 	if GOOS == "windows" && mp.libcallsp != 0 {
+		releasem(mp)
 		return false
 	}
+	releasem(mp)
 	return true
 }