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30998 commits

Author SHA1 Message Date
Alberto Donizetti
4601eae6ba doc/gdb: mention GOTRACEBACK=crash
Also fix a couple of other errors.

Fixes #6877

Change-Id: I94c81c5847cc7b0adab19418e71687bc2ee7fe94
Reviewed-on: https://go-review.googlesource.com/34960
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2017-01-13 18:05:46 +00:00
Keith Randall
4c4c5fc7a3 misc/cgo/testplugin: test that types and itabs are unique
Make sure that the same type and itab generated in two
different plugins are actually the same thing.

See also CL 35115

Change-Id: I0c1ecb039d7e2bf5a601d58dfa162a435ae4ef76
Reviewed-on: https://go-review.googlesource.com/35116
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
2017-01-13 17:31:33 +00:00
Austin Clements
22689c4450 reflect: keep makeFuncImpl live across makeFuncStub
When traceback sees reflect.makeFuncStub (or reflect.methodValueCall)
on the stack, it expects to be able to get the *reflect.makeFuncImpl
(or *reflect.methodValue) for that call from the first outgoing
argument slot of makeFuncStub/methodValueCall.

However, currently this object isn't necessarily kept live across
makeFuncStub. This means it may get garbage collected while in a
reflect call and reused for something else. If we then try to
traceback, the runtime will see a corrupted makeFuncImpl object and
panic. This was not a problem in previous releases because we always
kept arguments live across the whole function. This became a problem
when we stopped doing this.

Fix this by using reflect.KeepAlive to keep the
makeFuncImpl/methodValue live across all of callReflect/callMethod,
which in turn keeps it live as long as makeFuncStub/methodValueCall
are on the stack.

Fixes #18635.

Change-Id: I91853efcf17912390fddedfb0230648391c33936
Reviewed-on: https://go-review.googlesource.com/35151
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-01-13 03:45:28 +00:00
David Crawshaw
9cf06ed6cd cmd/link: only exclude C-only symbols on darwin
C-only symbols are excluded from pclntab because of a quirk of darwin,
where functions are referred to by an exported symbol so dynamic
relocations de-duplicate to the host binary module and break unwinding.

This doesn't happen on ELF systems because the linker always refers to
unexported module-local symbols, so we don't need this condition.
And the current logic for excluding some functions breaks the module
verification code in moduledataverify1. So disable this for plugins
on linux.

(In 1.9, it will probably be necessary to introduce a module-local
symbol reference system on darwin to fix a different bug, so all of
this onlycsymbol code made be short-lived.)

With this CL, the tests in CL 35116 pass.

Change-Id: I517d7ca4427241fa0a91276c462827efb9383be9
Reviewed-on: https://go-review.googlesource.com/35190
Reviewed-by: Michael Hudson-Doyle <michael.hudson@canonical.com>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-01-12 23:48:11 +00:00
Joe Tsai
9c3630f578 compress/flate: avoid large stack growth in fillDeflate
Ranging over an array causes the array to be copied over to the
stack, which cause large re-growths. Instead, we should iterate
over slices of the array.

Also, assigning a large struct literal uses the stack even
though the actual fields being populated are small in comparison
to the entirety of the struct (see #18636).

Fixing the stack growth does not alter CPU-time performance much
since the stack-growth and copying was such a tiny portion of the
compression work:

name                         old time/op    new time/op    delta
Encode/Digits/Default/1e4-8     332µs ± 1%     332µs ± 1%   ~     (p=0.796 n=10+10)
Encode/Digits/Default/1e5-8    5.07ms ± 2%    5.05ms ± 1%   ~       (p=0.815 n=9+8)
Encode/Digits/Default/1e6-8    53.7ms ± 1%    53.9ms ± 1%   ~     (p=0.075 n=10+10)
Encode/Twain/Default/1e4-8      380µs ± 1%     380µs ± 1%   ~     (p=0.684 n=10+10)
Encode/Twain/Default/1e5-8     5.79ms ± 2%    5.79ms ± 1%   ~      (p=0.497 n=9+10)
Encode/Twain/Default/1e6-8     61.5ms ± 1%    61.8ms ± 1%   ~     (p=0.247 n=10+10)

name                         old speed      new speed      delta
Encode/Digits/Default/1e4-8  30.1MB/s ± 1%  30.1MB/s ± 1%   ~     (p=0.753 n=10+10)
Encode/Digits/Default/1e5-8  19.7MB/s ± 2%  19.8MB/s ± 1%   ~       (p=0.795 n=9+8)
Encode/Digits/Default/1e6-8  18.6MB/s ± 1%  18.5MB/s ± 1%   ~     (p=0.072 n=10+10)
Encode/Twain/Default/1e4-8   26.3MB/s ± 1%  26.3MB/s ± 1%   ~     (p=0.616 n=10+10)
Encode/Twain/Default/1e5-8   17.3MB/s ± 2%  17.3MB/s ± 1%   ~      (p=0.484 n=9+10)
Encode/Twain/Default/1e6-8   16.3MB/s ± 1%  16.2MB/s ± 1%   ~     (p=0.238 n=10+10)

Updates #18636
Fixes #18625

Change-Id: I471b20339bf675f63dc56d38b3acdd824fe23328
Reviewed-on: https://go-review.googlesource.com/35122
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Joe Tsai <thebrokentoaster@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-01-12 19:15:57 +00:00
David Crawshaw
4f0aac52d9 cmd/go: add comment about SIGUSR2 on iOS
Missing from CL 34926.

Change-Id: I4a046440c30811f26da53bee0e853dae3b0ac57a
Reviewed-on: https://go-review.googlesource.com/35123
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2017-01-12 16:47:42 +00:00
David Crawshaw
333f764df3 cmd/go, misc: switch from breakpoint to SIGUSR2
The iOS test harness has set a breakpoint early in the life of Go
programs so that it can change the current working directory using
information only available from the host debugger. Somewhere in the
upgrade to iOS 10 / XCode 8.2, breakpoints stopped working. This
may be an LLDB bug, or a bug in the ios-deploy LLDB scripts, it's
not clear.

Work around the problem by giving up on breakpoints. Instead, early
in the life of every test binary built for iOS, send (and ignore) a
SIGUSR2 signal. The debugger will catch this, giving the script
go_darwin_arm_exec a chance to change the working directory.

For the iOS builders.

Change-Id: I7476531985217d0c76bc176904c48379210576c2
Reviewed-on: https://go-review.googlesource.com/34926
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-01-12 15:46:46 +00:00
Shenghou Ma
39e31d5ec0 doc/go1.8: update timezone database version
Fixes #18623.

Change-Id: Ic965f5f7088c3270adbca7162226be486d1b9b4e
Reviewed-on: https://go-review.googlesource.com/35130
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2017-01-12 04:50:46 +00:00
Keith Randall
08da8201ca misc/cgo/testshared: test that types and itabs are unique
Make sure that the same type and itab generated in two
different shared library are actually the same thing.

Change-Id: Ica45862d65ff8bc7ad04d59a41f57223f71224cd
Reviewed-on: https://go-review.googlesource.com/35115
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2017-01-12 00:20:55 +00:00
Bryan C. Mills
fdde7ba2a2 runtime: avoid clobbering C callee-save register in cgoSigtramp
Use R11 (a caller-saved temp register) instead of RBX (a callee-saved
register).

I believe this only affects linux/amd64, since it is the only platform
with a non-trivial cgoSigtramp implementation.

Updates #18328.

Change-Id: I3d35c4512624184d5a8ece653fa09ddf50e079a2
Reviewed-on: https://go-review.googlesource.com/35068
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-01-12 00:06:32 +00:00
Josh Bleecher Snyder
f65abf6ddc cmd/compile: hide testdclstack behind debug flag
This reduces compilation time for the program
in #18602 from 7 hours to 30 min.

Updates #14781
Updates #18602

Change-Id: I3c4af878a08920e6373d3b3b0c4453ee002e32eb
Reviewed-on: https://go-review.googlesource.com/35113
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-01-11 23:39:50 +00:00
Joe Tsai
641ef2a733 compress/gzip: skip TestGZIPFilesHaveZeroMTimes on non-builders
Fixes #18604

Change-Id: I89221d5e632042167dfced068e1dc14e932cd618
Reviewed-on: https://go-review.googlesource.com/35111
Run-TryBot: Joe Tsai <thebrokentoaster@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2017-01-11 17:48:09 +00:00
Austin Clements
0724aa813f crypto/dsa: gofmt
Somehow this file didn't get gofmted after the last change, which
interferes with merges.

Change-Id: I965cfdbf27a01124a6ed300be9687ff84f68f9a1
Reviewed-on: https://go-review.googlesource.com/35064
Reviewed-by: Matt Layher <mdlayher@gmail.com>
Reviewed-by: Adam Langley <agl@chromium.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Matt Layher <mdlayher@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-01-11 17:10:59 +00:00
Brad Fitzpatrick
ac05542985 net/http: deflake TestRetryIdempotentRequestsOnError
The test was previously an integration test, relying on luck and many
goroutines and lots of time to hit the path to be tested.

Instead, rewrite the test to exactly hit the path to be tested, in one
try, in one goroutine.

Fixes #18205

Change-Id: I63cd513316344bfd7375dcc452c1c396dec0e49f
Reviewed-on: https://go-review.googlesource.com/35107
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2017-01-11 01:39:54 +00:00
Jaana Burcu Dogan
b842c9aac7 doc: remove inline styles
Change-Id: I7ca7e9a2d4cf97cf33c60a9a4d0ba5fb0ca6e44c
Reviewed-on: https://go-review.googlesource.com/35098
Reviewed-by: Chris Broadfoot <cbro@golang.org>
2017-01-10 22:54:19 +00:00
David Chase
d9a0579156 cmd/compile: disable flaky test
The test is inherently racy and vulnerable to starvation,
and within all.bash on some platforms that means it flakes.
Test is kept because it can be useful standalone to verify
behavior of GOEXPERIMENT=preeemptibleloops, and there is
likely to be further development of this feature in the
future.

There's also some question as to why it is flaking, because
though technically this is permitted, it's very odd in this
simple case.

Fixes #18589.

Change-Id: Ia0dd9037285c4a03122da4012c96981c9cc43b60
Reviewed-on: https://go-review.googlesource.com/35051
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
2017-01-10 17:29:46 +00:00
Austin Clements
2817e77024 runtime: debug prints for spanBytesAlloc underflow
Updates #18043.

Change-Id: I24e687fdd5521c48b672987f15f0d5de9f308884
Reviewed-on: https://go-review.googlesource.com/34612
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Rick Hudson <rlh@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-01-10 15:59:39 +00:00
David Chase
7f1ff65c39 cmd/compile: insert scheduling checks on loop backedges
Loop breaking with a counter.  Benchmarked (see comments),
eyeball checked for sanity on popular loops.  This code
ought to handle loops in general, and properly inserts phi
functions in cases where the earlier version might not have.

Includes test, plus modifications to test/run.go to deal with
timeout and killing looping test.  Tests broken by the addition
of extra code (branch frequency and live vars) for added
checks turn the check insertion off.

If GOEXPERIMENT=preemptibleloops, the compiler inserts reschedule
checks on every backedge of every reducible loop.  Alternately,
specifying GO_GCFLAGS=-d=ssa/insert_resched_checks/on will
enable it for a single compilation, but because the core Go
libraries contain some loops that may run long, this is less
likely to have the desired effect.

This is intended as a tool to help in the study and diagnosis
of GC and other latency problems, now that goal STW GC latency
is on the order of 100 microseconds or less.

Updates #17831.
Updates #10958.

Change-Id: I6206c163a5b0248e3f21eb4fc65f73a179e1f639
Reviewed-on: https://go-review.googlesource.com/33910
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2017-01-09 21:01:29 +00:00
Robert Griesemer
f412bd31ce cmd/compile: file line number for //go:xxx directives
Minimally invasive; fixes a regression from 1.7.

Fixes #18459.

Change-Id: I93b3b5c05706eaff8ae97a237f770838c1f8778c
Reviewed-on: https://go-review.googlesource.com/34721
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-01-09 19:39:56 +00:00
Joe Tsai
a8871194f2 net/http: preserve original HTTP method when possible
In Go1.7, a 301, 302, or 303 redirect on a HEAD method, would still
cause the following redirects to still use a HEAD.
In CL/29852 this behavior was changed such that those codes always
caused a redirect with the GET method. Fix this such that both
GET and HEAD will preserve the method.

Fixes #18570

Change-Id: I4bfe69872a30799419e3fad9178f907fe439b449
Reviewed-on: https://go-review.googlesource.com/34981
Run-TryBot: Joe Tsai <thebrokentoaster@gmail.com>
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-01-09 18:23:50 +00:00
Austin Clements
ffedff7e50 runtime: add table of size classes in a comment
Change-Id: I52fae67c9aeceaa23e70f2ef0468745b354f8c75
Reviewed-on: https://go-review.googlesource.com/34932
Reviewed-by: Minux Ma <minux@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2017-01-08 00:01:30 +00:00
gulyasm
3156736189 go/types: fix typo
Fixes #18562

Change-Id: Ic195a8606f09876e2667e4ef720b84a07d316f4a
Reviewed-on: https://go-review.googlesource.com/34939
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2017-01-07 23:55:24 +00:00
Kevin Burke
1ede11d13a os/user: document the difference between Username and Name
Fixes #18261.

Change-Id: I4bd7363aac4e62461f61fd95b3c7a18063412182
Reviewed-on: https://go-review.googlesource.com/34241
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2017-01-07 22:54:27 +00:00
shawnps
067bab00a8 all: fix misspellings
Change-Id: I429637ca91f7db4144f17621de851a548dc1ce76
Reviewed-on: https://go-review.googlesource.com/34923
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-01-07 16:53:25 +00:00
Ian Lance Taylor
8fa2344e98 net/http: don't do a background read if we've already done one
Fixes #18535

Change-Id: I9e49d33ce357a534529a6b0fcdbc09ff4fa98622
Reviewed-on: https://go-review.googlesource.com/34920
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2017-01-07 06:37:46 +00:00
Jaana Burcu Dogan
1fbdae5c3a cmd/go: add link to env varible guide to set custom GOPATH
Also moves the GOPATH env variable guide to
golang.org/wiki/SettingGOPATH.

Fixes #18294.

Change-Id: I88a2ce550df7466f8d2388d86bc8476dcf3c2ad6
Reviewed-on: https://go-review.googlesource.com/34918
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2017-01-07 00:53:18 +00:00
Mikio Hara
66063b2da8 vendor: update golang.org/x/crypto/chacha20poly1305
Updates golang.org/x/crypto/chacha20poly1305 to rev cb497ae for:
- chacha20poly1305: fix detection of BMI on amd64 (https://golang.org/cl/34852)
- chacha20poly1305: fix typos (https://golang.org/cl/34536)
- chacha20poly1305: fix typos (https://golang.org/cl/33855)
- chacha20poly1305: fix build constraints (https://golang.org/cl/32391)

Change-Id: I3a608b5e21b3a72b5aaa5d0afe6c6cffbb1d6fc1
Reviewed-on: https://go-review.googlesource.com/34871
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-01-07 00:38:37 +00:00
Brad Fitzpatrick
5ddfa69fef doc: update CONTRIBUTING.md a bit, mention proposal process
Fixes #18550

Change-Id: Ia08d0ef6964216fcc14fa63c2ba378d68daa2c02
Reviewed-on: https://go-review.googlesource.com/34917
Reviewed-by: Chris Broadfoot <cbro@golang.org>
2017-01-06 23:19:01 +00:00
Matthew Dempsky
116da1c64a net: disable RFC 6724 Rule 9 for IPv4 addresses
Rule 9 arguably doesn't make sense for IPv4 addresses, and so far it
has only caused problems (#13283, #18518). Disable it until we hear
from users that actually want/need it.

Fixes #18518.

Change-Id: I7b0dd75d03819cab8e0cd4c29f0c1dc8d2e9c179
Reviewed-on: https://go-review.googlesource.com/34914
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-01-06 20:55:48 +00:00
David Chase
41d2278eef cmd/compile: rewrite literal.method to ensure full initialization
CALLPART of STRUCTLIT did not check for incomplete initialization
of struct; modify PTRLIT treatment to force zeroing.

Test for structlit, believe this might have also failed for
arraylit.

Fixes #18410.

Change-Id: I511abf8ef850e300996d40568944665714efe1fc
Reviewed-on: https://go-review.googlesource.com/34622
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
2017-01-06 20:35:52 +00:00
Jaana Burcu Dogan
a37b9e8e70 doc: explain how to set GOPATH to a custom value
Updates #18294.

Change-Id: Ib6b84243a15ed921cc8960e5fa355fd7594181e6
Reviewed-on: https://go-review.googlesource.com/34821
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2017-01-06 19:34:22 +00:00
Russ Cox
b902a63ade runtime: fix corruption crash/race between select and stack growth
To implement the blocking of a select, a goroutine builds a list of
offers to communicate (pseudo-g's, aka sudog), one for each case,
queues them on the corresponding channels, and waits for another
goroutine to complete one of those cases and wake it up. Obviously it
is not OK for two other goroutines to complete multiple cases and both
wake the goroutine blocked in select. To make sure that only one
branch of the select is chosen, all the sudogs contain a pointer to a
shared (single) 'done uint32', which is atomically cas'ed by any
interested goroutines. The goroutine that wins the cas race gets to
wake up the select. A complication is that 'done uint32' is stored on
the stack of the goroutine running the select, and that stack can move
during the select due to stack growth or stack shrinking.

The relevant ordering to block and unblock in select is:

	1. Lock all channels.
	2. Create list of sudogs and queue sudogs on all channels.
	3. Switch to system stack, mark goroutine as asleep,
	   unlock all channels.
	4. Sleep until woken.
	5. Wake up on goroutine stack.
	6. Lock all channels.
	7. Dequeue sudogs from all channels.
	8. Free list of sudogs.
	9. Unlock all channels.

There are two kinds of stack moves: stack growth and stack shrinking.
Stack growth happens while the original goroutine is running.
Stack shrinking happens asynchronously, during garbage collection.

While a channel listing a sudog is locked by select in this process,
no other goroutine can attempt to complete communication on that
channel, because that other goroutine doesn't hold the lock and can't
find the sudog. If the stack moves while all the channel locks are
held or when the sudogs are not yet or no longer queued in the
channels, no problem, because no goroutine can get to the sudogs and
therefore to selectdone. We only need to worry about the stack (and
'done uint32') moving with the sudogs queued in unlocked channels.

Stack shrinking can happen any time the goroutine is stopped.
That code already acquires all the channel locks before doing the
stack move, so it avoids this problem.

Stack growth can happen essentially any time the original goroutine is
running on its own stack (not the system stack). In the first half of
the select, all the channels are locked before any sudogs are queued,
and the channels are not unlocked until the goroutine has stopped
executing on its own stack and is asleep, so that part is OK. In the
second half of the select, the goroutine wakes up on its own goroutine
stack and immediately locks all channels. But the actual call to lock
might grow the stack, before acquiring any locks. In that case, the
stack is moving with the sudogs queued in unlocked channels. Not good.
One goroutine has already won a cas on the old stack (that goroutine
woke up the selecting goroutine, moving it out of step 4), and the
fact that done = 1 now should prevent any other goroutines from
completing any other select cases. During the stack move, however,
sudog.selectdone is moved from pointing to the old done variable on
the old stack to a new memory location on the new stack. Another
goroutine might observe the moved pointer before the new memory
location has been initialized. If the new memory word happens to be
zero, that goroutine might win a cas on the new location, thinking it
can now complete the select (again). It will then complete a second
communication (reading from or writing to the goroutine stack
incorrectly) and then attempt to wake up the selecting goroutine,
which is already awake.

The scribbling over the goroutine stack unexpectedly is already bad,
but likely to go unnoticed, at least immediately. As for the second
wakeup, there are a variety of ways it might play out.

* The goroutine might not be asleep.
That will produce a runtime crash (throw) like in #17007:

	runtime: gp: gp=0xc0422dcb60, goid=2299, gp->atomicstatus=8
	runtime:  g:  g=0xa5cfe0, goid=0,  g->atomicstatus=0
	fatal error: bad g->status in ready

Here, atomicstatus=8 is copystack; the second, incorrect wakeup is
observing that the selecting goroutine is in state "Gcopystack"
instead of "Gwaiting".

* The goroutine might be sleeping in a send on a nil chan.
If it wakes up, it will crash with 'fatal error: unreachable'.

* The goroutine might be sleeping in a send on a non-nil chan.
If it wakes up, it will crash with 'fatal error: chansend:
spurious wakeup'.

* The goroutine might be sleeping in a receive on a nil chan.
If it wakes up, it will crash with 'fatal error: unreachable'.

* The goroutine might be sleeping in a receive on a non-nil chan.
If it wakes up, it will silently (incorrectly!) continue as if it
received a zero value from a closed channel, leaving a sudog queued on
the channel pointing at that zero vaue on the goroutine's stack; that
space will be reused as the goroutine executes, and when some other
goroutine finally completes the receive, it will do a stray write into
the goroutine's stack memory, which may cause problems. Then it will
attempt the real wakeup of the goroutine, leading recursively to any
of the cases in this list.

* The goroutine might have been running a select in a finalizer
(I hope not!) and might now be sleeping waiting for more things to
finalize. If it wakes up, as long as it goes back to sleep quickly
(before the real GC code tries to wake it), the spurious wakeup does
no harm (but the stack was still scribbled on).

* The goroutine might be sleeping in gcParkAssist.
If it wakes up, that will let the goroutine continue executing a bit
earlier than we would have liked. Eventually the GC will attempt the
real wakeup of the goroutine, leading recursively to any of the cases
in this list.

* The goroutine cannot be sleeping in bgsweep, because the background
sweepers never use select.

* The goroutine might be sleeping in netpollblock.
If it wakes up, it will crash with 'fatal error: netpollblock:
corrupted state'.

* The goroutine might be sleeping in main as another thread crashes.
If it wakes up, it will exit(0) instead of letting the other thread
crash with a non-zero exit status.

* The goroutine cannot be sleeping in forcegchelper,
because forcegchelper never uses select.

* The goroutine might be sleeping in an empty select - select {}.
If it wakes up, it will return to the next line in the program!

* The goroutine might be sleeping in a non-empty select (again).
In this case, it will wake up spuriously, with gp.param == nil (no
reason for wakeup), but that was fortuitously overloaded for handling
wakeup due to a closing channel and the way it is handled is to rerun
the select, which (accidentally) handles the spurious wakeup
correctly:

	if cas == nil {
		// This can happen if we were woken up by a close().
		// TODO: figure that out explicitly so we don't need this loop.
		goto loop
	}

Before looping, it will dequeue all the sudogs on all the channels
involved, so that no other goroutine will attempt to wake it.
Since the goroutine was blocked in select before, being blocked in
select again when the spurious wakeup arrives may be quite likely.
In this case, the spurious wakeup does no harm (but the stack was
still scribbled on).

* The goroutine might be sleeping in semacquire (mutex slow path).
If it wakes up, that is taken as a signal to try for the semaphore
again, not a signal that the semaphore is now held, but the next
iteration around the loop will queue the sudog a second time, causing
a cycle in the wakeup list for the given address. If that sudog is the
only one in the list, when it is eventually dequeued, it will
(due to the precise way the code is written) leave the sudog on the
queue inactive with the sudog broken. But the sudog will also be in
the free list, and that will eventually cause confusion.

* The goroutine might be sleeping in notifyListWait, for sync.Cond.
If it wakes up, (*Cond).Wait returns. The docs say "Unlike in other
systems, Wait cannot return unless awoken by Broadcast or Signal,"
so the spurious wakeup is incorrect behavior, but most callers do not
depend on that fact. Eventually the condition will happen, attempting
the real wakeup of the goroutine and leading recursively to any of the
cases in this list.

* The goroutine might be sleeping in timeSleep aka time.Sleep.
If it wakes up, it will continue running, leaving a timer ticking.
When that time bomb goes off, it will try to ready the goroutine
again, leading to any one of the cases in this list.

* The goroutine cannot be sleeping in timerproc,
because timerproc never uses select.

* The goroutine might be sleeping in ReadTrace.
If it wakes up, it will print 'runtime: spurious wakeup of trace
reader' and return nil. All future calls to ReadTrace will print
'runtime: ReadTrace called from multiple goroutines simultaneously'.
Eventually, when trace data is available, a true wakeup will be
attempted, leading to any one of the cases in this list.

None of these fatal errors appear in any of the trybot or dashboard
logs. The 'bad g->status in ready' that happens if the goroutine is
running (the most likely scenario anyway) has happened once on the
dashboard and eight times in trybot logs. Of the eight, five were
atomicstatus=8 during net/http tests, so almost certainly this bug.
The other three were atomicstatus=2, all near code in select,
but in a draft CL by Dmitry that was rewriting select and may or may
not have had its own bugs.

This bug has existed since Go 1.4. Until then the select code was
implemented in C, 'done uint32' was a C stack variable 'uint32 done',
and C stacks never moved. I believe it has become more common recently
because of Brad's work to run more and more tests in net/http in
parallel, which lengthens race windows.

The fix is to run step 6 on the system stack,
avoiding possibility of stack growth.

Fixes #17007 and possibly other mysterious failures.

Change-Id: I9d6575a51ac96ae9d67ec24da670426a4a45a317
Reviewed-on: https://go-review.googlesource.com/34835
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
2017-01-06 19:19:35 +00:00
Austin Clements
5dd978a283 runtime: expand HACKING.md
This adds high-level descriptions of the scheduler structures, the
user and system stacks, error handling, and synchronization.

Change-Id: I1eed97c6dd4a6e3d351279e967b11c6e64898356
Reviewed-on: https://go-review.googlesource.com/34290
Reviewed-by: Rick Hudson <rlh@golang.org>
2017-01-06 18:30:36 +00:00
Austin Clements
618c291544 runtime: update big mgc.go comment
The comment describing the overall GC algorithm at the top of mgc.go
has gotten woefully out-of-date (and was possibly never
correct/complete). Update it to reflect the current workings of the
GC and the set of phases that we now divide it into.

Change-Id: I02143c0ebefe9d4cd7753349dab8045f0973bf95
Reviewed-on: https://go-review.googlesource.com/34711
Reviewed-by: Rick Hudson <rlh@golang.org>
2017-01-06 18:22:35 +00:00
Russ Cox
cb91dccd86 net/http: better failure in TestTransportPersistConnLeak
If one of the c.Get(ts.URL) results in an error, the child goroutine
calls t.Errorf, but the test goroutine gets stuck waiting for <-gotReqCh,
so the test hangs and the program is eventually killed (after 10 minutes!).
Whatever might have been printed to t.Errorf is never seen.
Adjust test so that the test fails cleanly in this case.

Still trying to debug why c.Get might fail.
It seems to have something to do with occasional connection
failures on macOS Sierra.

Change-Id: Ia797787bd51ea7cd6deb1192aec89c331c4f2c48
Reviewed-on: https://go-review.googlesource.com/34836
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2017-01-06 16:28:57 +00:00
Austin Clements
7aefdfded0 runtime: use 4K as the boundary of legal pointers
Currently, the check for legal pointers in stack copying uses
_PageSize (8K) as the minimum legal pointer. By default, Linux won't
let you map under 64K, but

1) it's less clear what other OSes allow or will allow in the future;

2) while mapping the first page is a terrible idea, mapping anywhere
above that is arguably more justifiable;

3) the compiler only assumes the first physical page (4K) is never
mapped.

Make the runtime consistent with the compiler and more robust by
changing the bad pointer check to use 4K as the minimum legal pointer.

This came out of discussions on CLs 34663 and 34719.

Change-Id: Idf721a788bd9699fb348f47bdd083cf8fa8bd3e5
Reviewed-on: https://go-review.googlesource.com/34890
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
2017-01-06 16:19:14 +00:00
Kevin Burke
867dcb5570 net: Fix grammar error
Change-Id: I1c2e17b25ca91be37a18c47e70678c3753070fb8
Reviewed-on: https://go-review.googlesource.com/34827
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
2017-01-06 01:58:00 +00:00
Mikio Hara
b07363da16 net: display the complete BUGS section on every platform
We cannot assume that the platform running documentation service is
the target platform.

Change-Id: I241ed6f8778169faac9ef49e11dcd40f7422cccc
Reviewed-on: https://go-review.googlesource.com/34750
Run-TryBot: Mikio Hara <mikioh.mikioh@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2017-01-06 00:04:24 +00:00
Emmanuel Odeke
b03dce927b cmd/compile: avoid n.Right nil dereference on non-existent interface methods
Fixes #18392.

Avoid nil dereferencing n.Right when dealing with non-existent
self referenced interface methods e.g.
type A interface{
  Fn(A.Fn)
}

Instead, infer the symbol name from n.Sym itself.

Change-Id: I60d5f8988e7318693e5c8da031285d8d7347b771
Reviewed-on: https://go-review.googlesource.com/34817
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2017-01-05 22:09:25 +00:00
Brad Fitzpatrick
ea53e61c6c doc: add go get -insecure change to go1.8.html
Change-Id: I184c86edaaaa71c26bc7360c8b995015f30fe137
Reviewed-on: https://go-review.googlesource.com/34819
Reviewed-by: Russ Cox <rsc@golang.org>
2017-01-05 18:58:37 +00:00
Brad Fitzpatrick
7d977e4279 cmd/go: use ProxyFromEnvironment in -insecure mode also
Be consistent on whether the http proxy environment variables are
respected regardless of whether -insecure is used.

Updates #18519

Change-Id: Ib157eaacfd342dd3bfcd03e64da18c98c609cae3
Reviewed-on: https://go-review.googlesource.com/34818
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-01-05 18:29:19 +00:00
Lion Yang
b820ef5c33 x/crypto/chacha20poly1305: fix detection of BMI on AMD64
This change uses runtime.support_bmi2 as an additional condition
to examine the usability of AVX2 version algorithm, fixes
the crash on the platfrom which supports AVX2 but not support BMI2.

Fixes #18512

Change-Id: I408c0844ae2eb242dacf70cb9e8cec1b8f3bd941
Reviewed-on: https://go-review.googlesource.com/34851
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-01-05 17:50:56 +00:00
Lion Yang
a2b615d527 crypto: detect BMI usability on AMD64 for sha1 and sha256
The existing implementations on AMD64 only detects AVX2 usability,
when they also contains BMI (bit-manipulation instructions).
These instructions crash the running program as 'unknown instructions'
on the architecture, e.g. i3-4000M, which supports AVX2 but not
support BMI.

This change added the detections for BMI1 and BMI2 to AMD64 runtime with
two flags as the result, `support_bmi1` and `support_bmi2`,
in runtime/runtime2.go. It also completed the condition to run AVX2 version
in packages crypto/sha1 and crypto/sha256.

Fixes #18512

Change-Id: I917bf0de365237740999de3e049d2e8f2a4385ad
Reviewed-on: https://go-review.googlesource.com/34850
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-01-05 15:37:37 +00:00
Russ Cox
f5608c20f7 .gitignore: fix attempt at rooted paths
When I wrote the lines

	bin/
	pkg/

I was trying to match just the top-level bin and pkg directories, and I put the
final slash in because 'git help gitignore' says:

       o   If the pattern does not contain a slash /, Git treats it as a shell
           glob pattern and checks for a match against the pathname relative
           to the location of the .gitignore file (relative to the toplevel of
           the work tree if not from a .gitignore file).

       o   Otherwise, Git treats the pattern as a shell glob suitable for
           consumption by fnmatch(3) with the FNM_PATHNAME flag: wildcards in
           the pattern will not match a / in the pathname. For example,
           "Documentation/*.html" matches "Documentation/git.html" but not
           "Documentation/ppc/ppc.html" or
           "tools/perf/Documentation/perf.html".

Putting a trailing slash was my way of opting in to the "rooted path" semantics
without looking different from the surrounding rooted paths like "src/go/build/zcgo.go".

But HA HA GIT FOOLED YOU! above those two bullets the docs say:

       o   If the pattern ends with a slash, it is removed for the purpose of
           the following description, ...

Change all the patterns to use a leading slash for "rooted" behavior.

This bit me earlier today because I had a perfectly reasonable source
code directory go/src/cmd/go/testdata/src/empty/pkg that was
not added by 'git add empty'.

Change-Id: I6f8685b3c5be22029c33de9ccd735487089a1c03
Reviewed-on: https://go-review.googlesource.com/34832
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2017-01-05 01:29:25 +00:00
Brad Fitzpatrick
c3fc9b4b81 lib/time: update tzdata to 2016j
Fixes #18500

Change-Id: I4dddd1b99aecf86b9431b0c14f452152dff9b95a
Reviewed-on: https://go-review.googlesource.com/34816
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-01-05 01:00:53 +00:00
Kale Blankenship
2547aec42a cmd/go: retain test binary when go test is run with -mutexprofile
Fixes #18494

Change-Id: I8a190acae6d5f1d20d4e4e4547d84e10e8a7fe68
Reviewed-on: https://go-review.googlesource.com/34793
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
2017-01-05 00:57:43 +00:00
Brad Fitzpatrick
2815045a50 net/http/httputil: make DumpRequest and DumpRequestOut recognize http.NoBody
Fixes #18506

Change-Id: I6b0b107296311178938609e878e1ef47a30a463f
Reviewed-on: https://go-review.googlesource.com/34814
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2017-01-04 23:02:08 +00:00
Brad Fitzpatrick
ecac827573 net/http: make Server cancel its ReadTimeout between requests
Fixes #18447

Change-Id: I5d60c3632a5ce625d3bac9d85533ce689e301707
Reviewed-on: https://go-review.googlesource.com/34813
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-01-04 21:17:22 +00:00
Ian Lance Taylor
7fb1640613 testing: add missing newlines to error messages
No test because in practice these errors never occur.

Change-Id: I11c77893ae931fc621c98920cba656790d18ed93
Reviewed-on: https://go-review.googlesource.com/34811
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2017-01-04 20:54:33 +00:00
Russ Cox
3fa53f1229 cmd/go: add sync/atomic dependency when needed by test coverage
Fixes #18486.

Change-Id: I359dc4169e04b4123bd41679ea939b06fa754ac2
Reviewed-on: https://go-review.googlesource.com/34830
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2017-01-04 20:01:46 +00:00