The logic for detecting deferreturn calls is wrong.

We used to look for a relocation whose symbol is runtime.deferreturn
and has an offset of 0. But on some architectures, the relocation
offset is not zero. These include arm (the offset is 0xebfffffe) and
s390x (the offset is 6).

This ends up setting the deferreturn offset at 0, so we end up using
the entry point live map instead of the deferreturn live map in a
frame which defers and then segfaults.

Instead, use the IsDirectJump helper to find calls.

Fixes #32484

Change-Id: Iecb530a7cf6eabd7233be7d0731ffa78873f3a54
Reviewed-on: https://go-review.googlesource.com/c/go/+/181258
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
(cherry picked from commit 9eb40315)
Reviewed-on: https://go-review.googlesource.com/c/go/+/181262Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>

This is a backport of CL 178397.

Updates #32167
Fixes #32168

Change-Id: Idb16a01d56814ea09ad277798787355dc6a3121f
Reviewed-on: https://go-review.googlesource.com/c/go/+/181437Reviewed-by: Jason Donenfeld <Jason@zx2c4.com>
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Run-TryBot: Jason Donenfeld <Jason@zx2c4.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

This fixes TestScript/cover_pkgall_multiple_mains, which started
failing after CL 174657.

When compiling main packages with coverage instrumentation
(e.g., for -coverpkg all), we now pass -p with the full import path
instead of '-p main'. This avoids link errors
'duplicate symbol main.main (types 1 and 1)'.

Fixes #32295
Updates #31946
Updates #32150

Change-Id: Id147527b1dbdc14bb33ac133c30d50c250b4365c
Reviewed-on: https://go-review.googlesource.com/c/go/+/176558
Run-TryBot: Jay Conrod <jayconrod@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
(cherry picked from commit 3b8c8041)
Reviewed-on: https://go-review.googlesource.com/c/go/+/179677

HTTP 408 responses now exist and are seen in the wild (e.g. from
Google's GFE), so make Go's HTTP client not spam about them when seen.
They're normal (now).

Fixes #32367
Updates #32310

Change-Id: I558eb4654960c74cf20db1902ccaae13d03310f6
Reviewed-on: https://go-review.googlesource.com/c/go/+/179457
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
(cherry picked from commit ba66d89d)
Reviewed-on: https://go-review.googlesource.com/c/go/+/181239
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

CFDictionaryGetValueIfPresent does not take ownership of the value, so
releasing the properties dictionary before passing the value to CFEqual
can crash. Not really clear why this works most of the time.

See https://developer.apple.com/library/archive/documentation/CoreFoundation/Conceptual/CFMemoryMgmt/Concepts/Ownership.html

Fixes #32282
Updates #28092
Updates #30763

Change-Id: I5ee7ca276b753a48abc3aedfb78b8af68b448dd4
Reviewed-on: https://go-review.googlesource.com/c/go/+/178537Reviewed-by: Adam Langley <agl@golang.org>
(cherry picked from commit a3d4655c)
Reviewed-on: https://go-review.googlesource.com/c/go/+/179339
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>

This is CVE-2019-11888.

Previously, passing a nil environment but a non-nil token would result
in the new potentially unprivileged process inheriting the parent
potentially privileged environment, or would result in the new
potentially privileged process inheriting the parent potentially
unprivileged environment. Either way, it's bad. In the former case, it's
an infoleak. In the latter case, it's a possible EoP, since things like
PATH could be overwritten.

Not specifying an environment currently means, "use the existing
environment". This commit amends the behavior to be, "use the existing
environment of the token the process is being created for." The behavior
therefore stays the same when creating processes without specifying a
token. And it does the correct thing when creating processes when
specifying a token.

Updates #32000
Fixes #32081

Change-Id: Ib4a90cfffb6ba866c855f66f1313372fdd34ce41
Reviewed-on: https://go-review.googlesource.com/c/go/+/177538
Run-TryBot: Jason Donenfeld <Jason@zx2c4.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

If a slice's entries are sparse, we decide to initialize it dynamically
instead of statically. That's CL 151319.

But if we do initialize it dynamically, we still need to initialize
the static entries. Typically we do that, but the bug fixed here is
that we don't if the entry's value is itself an array or struct.

To fix, use initKindLocalCode to ensure that both static and
dynamic entries are initialized via code.

Fixes #32013

Change-Id: I1192ffdbfb5cd50445c1206c4a3d8253295201dd
Reviewed-on: https://go-review.googlesource.com/c/go/+/176904
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
(cherry picked from commit a9e107c8)
Reviewed-on: https://go-review.googlesource.com/c/go/+/177040Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Satisfies the Apple Notary.

Fixes #30526

Change-Id: I91cf2d706a3ebe79bafdb759a0d32266ed6b9096
Reviewed-on: https://go-review.googlesource.com/c/go/+/175918
Run-TryBot: Elias Naur <mail@eliasnaur.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-on: https://go-review.googlesource.com/c/go/+/175919Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: Ib253d4aafab3ad65b4ba666f4eeb8b2f245997a1
Reviewed-on: https://go-review.googlesource.com/c/go/+/175447
Run-TryBot: Andrew Bonventre <andybons@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

info.Name returns a name relative to the directory, so we need to
prefix that directory in the Stat call.

(This was missed in CL 141097 due to the fact that the test only
happened to check symlinks in the current directory.)

This allows the misc/ tests to work in module mode on platforms that
support symlinks.

Updates #30228
Updates #28107
Fixes #31763

Change-Id: Ie31836382df0cbd7d203b7a8b637c4743d68b6f3
Reviewed-on: https://go-review.googlesource.com/c/163517
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/175441Reviewed-by: Andrew Bonventre <andybons@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Change-Id: I9986a323db2a8f5fa74b071cfd04e8c786da0cb3
Reviewed-on: https://go-review.googlesource.com/c/go/+/175438Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
(cherry picked from commit 1560264f)
Reviewed-on: https://go-review.googlesource.com/c/go/+/175444Reviewed-by: Andrew Bonventre <andybons@golang.org>

Change-Id: Icca4495f727e3921b717a4bbb441cd832d321d46
Reviewed-on: https://go-review.googlesource.com/c/go/+/175439Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
(cherry picked from commit e1f9e701)
Reviewed-on: https://go-review.googlesource.com/c/go/+/175443Reviewed-by: Andrew Bonventre <andybons@golang.org>

Fixes #31783

Change-Id: I3cc0ebc4be34d7c2d2d4fd655bfd0c2515ff3021
Reviewed-on: https://go-review.googlesource.com/c/go/+/174739Reviewed-by: Jay Conrod <jayconrod@google.com>
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
(cherry picked from commit fad365ba)
Reviewed-on: https://go-review.googlesource.com/c/go/+/175419
Run-TryBot: Andrew Bonventre <andybons@golang.org>
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Stack object generation code was always using the local package name
for its symbol. Normally that doesn't matter, as we usually only
compile functions in the local package. But for wrappers, the compiler
generates functions which live in other packages. When there are two
other packages with identical functions to wrap, the same name appears
twice, and the compiler goes boom.

Fixes #31396

Change-Id: I7026eebabe562cb159b8b6046cf656afd336ba25
Reviewed-on: https://go-review.googlesource.com/c/go/+/171464
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
(cherry picked from commit 43001a0d)
Reviewed-on: https://go-review.googlesource.com/c/go/+/173317Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Add explicit tests for:

 #30465	cmd/vet: Consider reverting tag conflict for embedded fields
 #30399	cmd/vet: possible to get a printf false positive with big.Int

because we have managed not to fix them in the last
couple point releases, and it will be too embarrassing
to do that yet again.

Change-Id: Ib1da5df870348b6eb9bfc8a87c507ecc6d44b8dd
Reviewed-on: https://go-review.googlesource.com/c/go/+/174520
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

[release-branch.go1.12] cmd/vendor/golang.org/x/tools/go/analysis: update from release-branch.go1.12

$ ./update-xtools.sh
Copied /Users/rsc/src/golang.org/x/tools@aa829657 to .
$ cd ~/src/golang.org/x/tools
$ git log -n1 aa829657
commit aa82965741a9fecd12b026fbb3d3c6ed3231b8f8 (HEAD -> release-branch.go1.12, origin/release-branch.go1.12)
Author:     Daniel Martí <mvdan@mvdan.cc>
AuthorDate: Fri Mar 1 11:00:19 2019 +0000
Commit:     Brad Fitzpatrick <bradfitz@golang.org>
CommitDate: Wed Mar 13 21:06:03 2019 +0000
...
$

Picks up cmd/vet fixes that have been inadvertently missed in point releases so far.

Fixes #30399.
Fixes #30465.

Change-Id: Ibcfaac51d134205b986b32f857d54006b19c896a
Reviewed-on: https://go-review.googlesource.com/c/go/+/174519
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This reverts commit 8e093e7a
(CL 159500).

Reason for revert: Increases memory allocation latency in certain
situations.

Fixes #31679.

Change-Id: I15e02c53a58009fd907b619b8649de2cdeb29ef0
Reviewed-on: https://go-review.googlesource.com/c/go/+/174102
Run-TryBot: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Austin Clements <austin@google.com>

This change modifies the implementation of mTreap.find to find the
best-fit span with the lowest possible base address.

Fixes #31677.

Change-Id: Ib4bda0f85d7d0590326f939a243a6e4665f37d3f
Reviewed-on: https://go-review.googlesource.com/c/go/+/173479
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
(cherry picked from commit 8c05d676)
Reviewed-on: https://go-review.googlesource.com/c/go/+/173939Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This change exports the runtime mTreap in export_test.go and then adds a
series of tests which check that the invariants of the treap are
maintained under different operations. These tests also include tests
for the treap iterator type.

Also, we note that the find() operation on the treap never actually was
best-fit, so the tests just ensure that it returns an appropriately
sized span.

For #30333.

Change-Id: If81f7c746dda6677ebca925cb0a940134701b894
Reviewed-on: https://go-review.googlesource.com/c/go/+/164100
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
(cherry picked from commit d13a9312)
Reviewed-on: https://go-review.googlesource.com/c/go/+/173940Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

The top right menu in Gerrit is now a gear icon, and the link
has a slightly different title.

Change-Id: I3f5d194f31ad09a99416a45db392aa4b5c7d98ff
Reviewed-on: https://go-review.googlesource.com/c/go/+/173400Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
(cherry picked from commit d0fadb93)
Reviewed-on: https://go-review.googlesource.com/c/go/+/173361Reviewed-by: Andrew Bonventre <andybons@golang.org>

The test doesn't really require cgo, but it does require that we know
the right flags to use to run the C compiler, and that is not
necessarily correct if we don't support cgo.

Fixes #31565

Change-Id: I04dc8db26697caa470e91ad712376aa621cf765d
Reviewed-on: https://go-review.googlesource.com/c/go/+/172981
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
(cherry picked from commit 4c236b9b)
Reviewed-on: https://go-review.googlesource.com/c/go/+/173117

New versions of clang can generate multiple sections named ".text"
when using vague C++ linkage. This is valid ELF, but would cause the
Go linker to report an error when using internal linking:
    symbol PACKAGEPATH(.text) listed multiple times
Avoid the problem by renaming section symbol names if there is a name
collision.

Change-Id: I41127e95003d5b4554aaf849177b3fe000382c02
Reviewed-on: https://go-review.googlesource.com/c/go/+/172697
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
(cherry picked from commit 3235f7c0)
Reviewed-on: https://go-review.googlesource.com/c/go/+/172701

Change-Id: I3cb4fb7cacba51bfd611ade918f16c618e2569fd
Reviewed-on: https://go-review.googlesource.com/c/go/+/172159Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
(cherry picked from commit e47090ab)
Reviewed-on: https://go-review.googlesource.com/c/go/+/172317Reviewed-by: Andrew Bonventre <andybons@golang.org>

Updates #31468
Fixes #31474

Change-Id: I5c4e61631b8af35bfc14b0cb9bc77feec100e340
Reviewed-on: https://go-review.googlesource.com/c/go/+/172058
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
(cherry picked from commit 3ebd9523)
Reviewed-on: https://go-review.googlesource.com/c/go/+/172080

Change-Id: I4d1b5e00ab4480b4c5adeeb4f53ddfdfa3903b71
Reviewed-on: https://go-review.googlesource.com/c/go/+/171838
Run-TryBot: Andrew Bonventre <andybons@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Updates #31293

Change-Id: I3d72f732be7b28059310ea6fc134c3bfac81492d
Reviewed-on: https://go-review.googlesource.com/c/go/+/171578Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
(cherry picked from commit ab2a0803)
Reviewed-on: https://go-review.googlesource.com/c/go/+/171766Reviewed-by: Bryan C. Mills <bcmills@google.com>

Change-Id: Iab946b7c903e3c30addc388900421a7ceb803f1c
Reviewed-on: https://go-review.googlesource.com/c/go/+/171149
Run-TryBot: Andrew Bonventre <andybons@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Andrew Bonventre <andybons@golang.org>

Change-Id: I09e0c2720ec0a51dc73c24b4550a749448656025
Reviewed-on: https://go-review.googlesource.com/c/go/+/171143Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
(cherry picked from commit 6f512c8d)
Reviewed-on: https://go-review.googlesource.com/c/go/+/171157Reviewed-by: Andrew Bonventre <andybons@golang.org>

Change-Id: I6dd60ea7b8a8756be97503e163c2386af16e4e12
Reviewed-on: https://go-review.googlesource.com/c/go/+/171144Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
(cherry picked from commit 973c0312)
Reviewed-on: https://go-review.googlesource.com/c/go/+/171147Reviewed-by: Andrew Bonventre <andybons@golang.org>

Change-Id: Ia06f7005f466e55a22c76bf2b47d74ee8eb77dd1
Reviewed-on: https://go-review.googlesource.com/c/go/+/171139Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
(cherry picked from commit 739a78f2)
Reviewed-on: https://go-review.googlesource.com/c/go/+/171145Reviewed-by: Andrew Bonventre <andybons@golang.org>

Change-Id: I84c9a8ddbd3101dd478e4a8a4e191863e68c6af6
Reviewed-on: https://go-review.googlesource.com/c/go/+/171140Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
(cherry picked from commit 8759b4d3)
Reviewed-on: https://go-review.googlesource.com/c/go/+/171141

Change-Id: I07e4404196886b7754414726f25092cca39861a7
Reviewed-on: https://go-review.googlesource.com/c/go/+/170888
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This fixes two problems missed in CL 164877.

First, p.Internal.BuildInfo is now part of the cache key. This is
important since p.Internal.BuildInfo causes the build action to
synthesize a new source file, which affects the output.

Second, recompileForTest is always called for test
packages. Previously, it was only called when there were internal test
sources, so the fix in CL 164877 did not apply to packages that only
had external tests.

Fixes #30937

Change-Id: Iac2d7e8914f0313f9ab4222299a866f67889eb2e
Reviewed-on: https://go-review.googlesource.com/c/go/+/168200
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
(cherry picked from commit d34548e0)
Reviewed-on: https://go-review.googlesource.com/c/go/+/168717
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

The current wasm write barrier implementation incorrectly implements
the "deletion" part of the barrier. It correctly greys the new value
of the pointer, but rather than also greying the old value of the
pointer, it greys the object containing the slot (which, since the old
value was just overwritten, is not going to contain the old value).

This can lead to unmarked, reachable objects.

Often, this is masked by other marking activity, but one specific
sequence that can lead to an unmarked object because of this bug is:

1. Initially, GC is off, object A is reachable from just one pointer
in the heap.

2. GC starts and scans the stack of goroutine G.

3. G copies the pointer to A on to its stack and overwrites the
pointer to A in the heap. (Now A is reachable only from G's stack.)

4. GC finishes while A is still reachable from G's stack.

With a functioning deletion barrier, step 3 causes A to be greyed.
Without a functioning deletion barrier, nothing causes A to be greyed,
so A will be freed even though it's still reachable from G's stack.

This CL fixes the wasm write barrier.

Fixes #30873.

Change-Id: I8a74ee517facd3aa9ad606e5424bcf8f0d78e754
Reviewed-on: https://go-review.googlesource.com/c/go/+/167743
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
(cherry picked from commit d9db9e32)
Reviewed-on: https://go-review.googlesource.com/c/go/+/167745Reviewed-by: Katie Hockman <katie@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: I990c451ff24844b39dee2477cec4caa9db2e8ebb
Reviewed-on: https://go-review.googlesource.com/c/go/+/170883Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
(cherry picked from commit 5ec938cd)
Reviewed-on: https://go-review.googlesource.com/c/go/+/170885Reviewed-by: Andrew Bonventre <andybons@golang.org>

Change-Id: Iec5e69b3ea163f42234d3b73696427a7aa8732e3
Reviewed-on: https://go-review.googlesource.com/c/go/+/170884Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
(cherry picked from commit e47ced78)
Reviewed-on: https://go-review.googlesource.com/c/go/+/170886Reviewed-by: Andrew Bonventre <andybons@golang.org>

This reverts commit 731ebf4d.

Reason for revert: It's not working for large directories.

Change-Id: Ie0f88e0ed1d36c4ea4f32d2acd4e223bd8229ca0
Reviewed-on: https://go-review.googlesource.com/c/go/+/170882Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Andrew Bonventre <andybons@golang.org>

Getdirentries is implemented with the __getdirentries64 function
in libSystem.dylib. That function works, but it's on Apple's
can't-be-used-in-an-app-store-application list.

Implement Getdirentries using the underlying fdopendir/readdir_r/closedir.
The simulation isn't faithful, and could be slow, but it should handle
common cases.

Don't use Getdirentries in the stdlib, use fdopendir/readdir_r/closedir
instead (via (*os.File).readdirnames).

(Incorporates CL 170837 and CL 170698, which were small fixes to the
original tip CL.)

Fixes #31244

Update #28984

RELNOTE=yes

Change-Id: Ia6b5d003e5bfe43ba54b1e1d9cfa792cc6511717
Reviewed-on: https://go-review.googlesource.com/c/go/+/168479Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
(cherry picked from commit 9da6530f)
Reviewed-on: https://go-review.googlesource.com/c/go/+/170640
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>

It's broken on our builders (once we enabled dev mode on our Macs,
see CL 170339)

Updates #31188

Change-Id: Iceea65dc79576057b401a461bfe39254fed1f7ed
Reviewed-on: https://go-review.googlesource.com/c/go/+/170281Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
(cherry picked from commit 46c3e217)
Reviewed-on: https://go-review.googlesource.com/c/go/+/170798
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

fd.l.Lock shouldn't be called in a loop.

Manual backport of CL 165598. It could not be cherry-picked due to conflicts.

Fixes #31211

Change-Id: Ib76e679f6a276b32fe9c1594b7e9a506017a7967
Reviewed-on: https://go-review.googlesource.com/c/go/+/170680
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>