net/http: apparent deadlock in TestHandlerPanic

[bcmills]

greplogs --dashboard -md -l -e net/http\\.\\\(\\\*Client\\\)\\.Get.\*\\n\\t.\*\\nnet/http_test\\.testHandlerPanic

2022-01-04T22:05:15-e39ab9b/windows-arm64-10

goroutine 1523 [sync.Cond.Wait, 2 minutes]:
runtime.gopark(0x7ff6e9e5f3d0?, 0x4000285400?, 0x0?, 0x0?, 0xe7791f701?)
	C:/workdir/go/src/runtime/proc.go:366 +0xe8 fp=0x4000717770 sp=0x4000717750 pc=0x7ff6e9df94a8
runtime.goparkunlock(...)
	C:/workdir/go/src/runtime/proc.go:372
sync.runtime_notifyListWait(0x40001d1610, 0x0)
	C:/workdir/go/src/runtime/sema.go:513 +0x178 fp=0x40007177c0 sp=0x4000717770 pc=0x7ff6e9e22958
sync.(*Cond).Wait(0x40001d1600)
	C:/workdir/go/src/sync/cond.go:56 +0xd8 fp=0x4000717800 sp=0x40007177c0 pc=0x7ff6e9e2f388
net/http.(*connReader).abortPendingRead(0x40005cbb60)
	C:/workdir/go/src/net/http/server.go:720 +0xc8 fp=0x4000717850 sp=0x4000717800 pc=0x7ff6ea0345c8
net/http.(*conn).serve.func1()
	C:/workdir/go/src/net/http/server.go:1833 +0x180 fp=0x40007178f0 sp=0x4000717850 pc=0x7ff6ea03aba0
panic({0x7ff6ea181480, 0x7ff6ea2d1ec0})
	C:/workdir/go/src/runtime/panic.go:844 +0x260 fp=0x40007179b0 sp=0x40007178f0 pc=0x7ff6e9df6700
net/http_test.testHandlerPanic.func1({0x7ff6ea2d6690?, 0x40003649a0?}, 0x7ff6e9e5f3d0?)
	C:/workdir/go/src/net/http/serve_test.go:2800 +0x4c fp=0x4000717a50 sp=0x40007179b0 pc=0x7ff6ea0e3afc
net/http.HandlerFunc.ServeHTTP(0x0?, {0x7ff6ea2d6690?, 0x40003649a0?}, 0x7ff6e9e01cec?)
	C:/workdir/go/src/net/http/server.go:2084 +0x3c fp=0x4000717a80 sp=0x4000717a50 pc=0x7ff6ea03b23c
net/http.serverHandler.ServeHTTP({0x40005cbb60?}, {0x7ff6ea2d6690, 0x40003649a0}, 0x4000282a00)
	C:/workdir/go/src/net/http/server.go:2916 +0x408 fp=0x4000717b40 sp=0x4000717a80 pc=0x7ff6ea03e8a8
net/http.(*conn).serve(0x4000628460, {0x7ff6ea2d6be8, 0x40002b01e0})
	C:/workdir/go/src/net/http/server.go:1966 +0x550 fp=0x4000717fa0 sp=0x4000717b40 pc=0x7ff6ea039f70
net/http.(*Server).Serve.func3()
	C:/workdir/go/src/net/http/server.go:3071 +0x34 fp=0x4000717fd0 sp=0x4000717fa0 pc=0x7ff6ea03f344
runtime.goexit()
	C:/workdir/go/src/runtime/asm_arm64.s:1259 +0x4 fp=0x4000717fd0 sp=0x4000717fd0 pc=0x7ff6e9e26dc4
created by net/http.(*Server).Serve
	C:/workdir/go/src/net/http/server.go:3071 +0x448

[…]

goroutine 1486 [select, 2 minutes]:
runtime.gopark(0x4000071648?, 0x6?, 0x28?, 0x13?, 0x4000071454?)
	C:/workdir/go/src/runtime/proc.go:366 +0xe8 fp=0x40000712d0 sp=0x40000712b0 pc=0x7ff6e9df94a8
runtime.selectgo(0x4000071648, 0x4000071448, 0x7ff6ea206e77?, 0x0, 0x4000071508?, 0x1)
	C:/workdir/go/src/runtime/select.go:328 +0x6d0 fp=0x40000713f0 sp=0x40000712d0 pc=0x7ff6e9e09b50
net/http.(*persistConn).roundTrip(0x400055a6c0, 0x40001d1580)
	C:/workdir/go/src/net/http/transport.go:2614 +0x804 fp=0x40000716b0 sp=0x40000713f0 pc=0x7ff6ea0564a4
net/http.(*Transport).roundTrip(0x40005b23c0, 0x4000282800)
	C:/workdir/go/src/net/http/transport.go:594 +0x6c0 fp=0x40000718f0 sp=0x40000716b0 pc=0x7ff6ea04b1b0
net/http.(*Transport).RoundTrip(0x40005cb860?, 0x7ff6ea2d3968?)
	C:/workdir/go/src/net/http/roundtrip.go:17 +0x20 fp=0x4000071910 sp=0x40000718f0 pc=0x7ff6ea032d80
net/http.send(0x4000282800, {0x7ff6ea2d3968, 0x40005b23c0}, {0x7ff6e9ff6bf8?, 0x8?, 0x0?})
	C:/workdir/go/src/net/http/client.go:252 +0x4ec fp=0x4000071af0 sp=0x4000071910 pc=0x7ff6e9ff52fc
net/http.(*Client).send(0x40005cb740, 0x4000282800, {0x80000?, 0x10000?, 0x0?})
	C:/workdir/go/src/net/http/client.go:176 +0xa4 fp=0x4000071b70 sp=0x4000071af0 pc=0x7ff6e9ff4c94
net/http.(*Client).do(0x40005cb740, 0x4000282800)
	C:/workdir/go/src/net/http/client.go:725 +0x714 fp=0x4000071d80 sp=0x4000071b70 pc=0x7ff6e9ff6c54
net/http.(*Client).Do(...)
	C:/workdir/go/src/net/http/client.go:593
net/http.(*Client).Get(0x400041ab60?, {0x40001a4198?, 0x7ff6ea2d4428?})
	C:/workdir/go/src/net/http/client.go:480 +0x7c fp=0x4000071de0 sp=0x4000071d80 pc=0x7ff6e9ff62bc
net/http_test.testHandlerPanic(0x400041ab60, 0x0, 0x17?, 0x0, {0x7ff6ea181480?, 0x7ff6ea2d1ec0})
	C:/workdir/go/src/net/http/serve_test.go:2822 +0x3c8 fp=0x4000071f20 sp=0x4000071de0 pc=0x7ff6ea0e36a8
net/http_test.TestHandlerPanic_h1(0x4000509f18?)
	C:/workdir/go/src/net/http/serve_test.go:2758 +0x3c fp=0x4000071f60 sp=0x4000071f20 pc=0x7ff6ea0e31fc
testing.tRunner(0x400041ab60, 0x7ff6ea24ee60)
	C:/workdir/go/src/testing/testing.go:1440 +0x110 fp=0x4000071fb0 sp=0x4000071f60 pc=0x7ff6e9eb7360
testing.(*T).Run.func1()
	C:/workdir/go/src/testing/testing.go:1487 +0x30 fp=0x4000071fd0 sp=0x4000071fb0 pc=0x7ff6e9eb80d0
runtime.goexit()
	C:/workdir/go/src/runtime/asm_arm64.s:1259 +0x4 fp=0x4000071fd0 sp=0x4000071fd0 pc=0x7ff6e9e26dc4
created by testing.(*T).Run
	C:/workdir/go/src/testing/testing.go:1487 +0x328

2021-11-15T18:43:07-0e65410/plan9-arm
2021-09-21T16:34:40-901ac46/plan9-arm
2020-12-10T23:11:25-1fe891a/ios-arm64-corellium
2019-06-11T17:29:22-5f94d44/darwin-arm64-mn4m2zdaios

CC @neild

[bcmills]

This bug may be very old and very hard to trigger. (See previously #13555 (2015), #4830 (2014), #2518 (2011); CC @bradfitz.)

[bcmills]

This has the same signature as #50469 — a deadlock in abortPendingRead that occurs only on ARM builders.

[bcmills]

Duplicate of #50469