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path: root/src/runtime/lock_futex.go
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2021-04-16runtime: move findrunnable timer delay computation closer to useMichael Pratt
findrunnable has a couple places where delta is recomputed from a new pollUntil value. This proves to be a pain in refactoring, as it is easy to forget to do properly. Move computation of delta closer to its use, where it is more logical anyways. This CL should have no functional changes. For #43997. For #44313. Change-Id: I89980fd7f40f8a4c56c7540cae03ff99e12e1422 Reviewed-on: https://go-review.googlesource.com/c/go/+/307910 Trust: Michael Pratt <mpratt@google.com> Run-TryBot: Michael Pratt <mpratt@google.com> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Michael Knyszek <mknyszek@google.com>
2021-02-20all: go fmt std cmd (but revert vendor)Russ Cox
Make all our package sources use Go 1.17 gofmt format (adding //go:build lines). Part of //go:build change (#41184). See https://golang.org/design/draft-gobuild Change-Id: Ia0534360e4957e58cd9a18429c39d0e32a6addb4 Reviewed-on: https://go-review.googlesource.com/c/go/+/294430 Trust: Russ Cox <rsc@golang.org> Run-TryBot: Russ Cox <rsc@golang.org> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com> Reviewed-by: Ian Lance Taylor <iant@golang.org>
2020-05-31runtime: fix race condition between timer and event handlerRichard Musiol
This change fixes a race condition between beforeIdle waking up the innermost event handler and a timer causing a different goroutine to wake up at the exact same moment. This messes up the wasm event handling and leads to memory corruption. The solution is to make beforeIdle return the goroutine that must run next and have findrunnable pick this goroutine without considering timers again. Fixes #38093 Fixes #38574 Change-Id: Iffbe99411d25c2730953d1c8b0741fd892f8e540 Reviewed-on: https://go-review.googlesource.com/c/go/+/230178 Run-TryBot: Richard Musiol <neelance@gmail.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Cherry Zhang <cherryyz@google.com>
2020-05-07runtime: incorporate Gscan acquire/release into lock ranking orderDan Scales
I added routines that can acquire/release a particular rank without acquiring/releasing an associated lock. I added lockRankGscan as a rank for acquiring/releasing the Gscan bit. castogscanstatus() and casGtoPreemptScan() are acquires of the Gscan bit. casfrom_Gscanstatus() is a release of the Gscan bit. casgstatus() is like an acquire and release of the Gscan bit, since it will wait if Gscan bit is currently set. We have a cycle between hchan and Gscan. The acquisition of Gscan and then hchan only happens in syncadjustsudogs() when the G is suspended, so the main normal ordering (get hchan, then get Gscan) can't be happening. So, I added a new rank lockRankHchanLeaf that is used when acquiring hchan locks in syncadjustsudogs. This ranking is set so no other locks can be acquired except other hchan locks. Fixes #38922 Change-Id: I58ce526a74ba856cb42078f7b9901f2832e1d45c Reviewed-on: https://go-review.googlesource.com/c/go/+/228417 Run-TryBot: Dan Scales <danscales@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Austin Clements <austin@google.com>
2020-04-07runtime: static lock ranking for the runtime (enabled by GOEXPERIMENT)Dan Scales
I took some of the infrastructure from Austin's lock logging CR https://go-review.googlesource.com/c/go/+/192704 (with deadlock detection from the logs), and developed a setup to give static lock ranking for runtime locks. Static lock ranking establishes a documented total ordering among locks, and then reports an error if the total order is violated. This can happen if a deadlock happens (by acquiring a sequence of locks in different orders), or if just one side of a possible deadlock happens. Lock ordering deadlocks cannot happen as long as the lock ordering is followed. Along the way, I found a deadlock involving the new timer code, which Ian fixed via https://go-review.googlesource.com/c/go/+/207348, as well as two other potential deadlocks. See the constants at the top of runtime/lockrank.go to show the static lock ranking that I ended up with, along with some comments. This is great documentation of the current intended lock ordering when acquiring multiple locks in the runtime. I also added an array lockPartialOrder[] which shows and enforces the current partial ordering among locks (which is embedded within the total ordering). This is more specific about the dependencies among locks. I don't try to check the ranking within a lock class with multiple locks that can be acquired at the same time (i.e. check the ranking when multiple hchan locks are acquired). Currently, I am doing a lockInit() call to set the lock rank of most locks. Any lock that is not otherwise initialized is assumed to be a leaf lock (a very high rank lock), so that eliminates the need to do anything for a bunch of locks (including all architecture-dependent locks). For two locks, root.lock and notifyList.lock (only in the runtime/sema.go file), it is not as easy to do lock initialization, so instead, I am passing the lock rank with the lock calls. For Windows compilation, I needed to increase the StackGuard size from 896 to 928 because of the new lock-rank checking functions. Checking of the static lock ranking is enabled by setting GOEXPERIMENT=staticlockranking before doing a run. To make sure that the static lock ranking code has no overhead in memory or CPU when not enabled by GOEXPERIMENT, I changed 'go build/install' so that it defines a build tag (with the same name) whenever any experiment has been baked into the toolchain (by checking Expstring()). This allows me to avoid increasing the size of the 'mutex' type when static lock ranking is not enabled. Fixes #38029 Change-Id: I154217ff307c47051f8dae9c2a03b53081acd83a Reviewed-on: https://go-review.googlesource.com/c/go/+/207619 Reviewed-by: Dan Scales <danscales@google.com> Reviewed-by: Keith Randall <khr@golang.org> Run-TryBot: Dan Scales <danscales@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org>
2019-10-21runtime: add wasm support for timers on P'sIan Lance Taylor
When we put timers on P's, the wasm code will not be able to rely on the timer goroutine. Use the beforeIdle hook to schedule a wakeup. Updates #6239 Updates #27707 Change-Id: Idf6309944778b8c3d7178f5d09431940843ea233 Reviewed-on: https://go-review.googlesource.com/c/go/+/171827 Run-TryBot: Ian Lance Taylor <iant@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Michael Knyszek <mknyszek@google.com> Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
2018-11-10all: add support for synchronous callbacks to js/wasmRichard Musiol
With this change, callbacks returned by syscall/js.NewCallback get executed synchronously. This is necessary for the APIs of many JavaScript libraries. A callback triggered during a call from Go to JavaScript gets executed on the same goroutine. A callback triggered by JavaScript's event loop gets executed on an extra goroutine. Fixes #26045 Fixes #27441 Change-Id: I591b9e85ab851cef0c746c18eba95fb02ea9e85b Reviewed-on: https://go-review.googlesource.com/c/142004 Reviewed-by: Cherry Zhang <cherryyz@google.com> Run-TryBot: Cherry Zhang <cherryyz@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org>
2018-06-14runtime, sycall/js: add support for callbacks from JavaScriptRichard Musiol
This commit adds support for JavaScript callbacks back into WebAssembly. This is experimental API, just like the rest of the syscall/js package. The time package now also uses this mechanism to properly support timers without resorting to a busy loop. JavaScript code can call into the same entry point multiple times. The new RUN register is used to keep track of the program's run state. Possible values are: starting, running, paused and exited. If no goroutine is ready any more, the scheduler can put the program into the "paused" state and the WebAssembly code will stop running. When a callback occurs, the JavaScript code puts the callback data into a queue and then calls into WebAssembly to allow the Go code to continue running. Updates #18892 Updates #25506 Change-Id: Ib8701cfa0536d10d69bd541c85b0e2a754eb54fb Reviewed-on: https://go-review.googlesource.com/114197 Reviewed-by: Austin Clements <austin@google.com> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2018-04-26runtime: remove the dummy arg of getcallerspCherry Zhang
getcallersp is intrinsified, and so the dummy arg is no longer needed. Remove it, as well as a few dummy args that are solely to feed getcallersp. Change-Id: Ibb6c948ff9c56537042b380ac3be3a91b247aaa6 Reviewed-on: https://go-review.googlesource.com/109596 Run-TryBot: Cherry Zhang <cherryyz@google.com> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-05-29runtime: fix stack split at bad time when disable inliningWei Xiao
key32 is called between entersyscallblock and exitsyscall stack split may occur if disable inlining and the G is preempted Fix the problem by describing key32 as nosplit function Fixes #20510 Change-Id: I1f0787995936f34ef0052cf79fde036f1b338865 Reviewed-on: https://go-review.googlesource.com/44390 Reviewed-by: Ian Lance Taylor <iant@golang.org> Run-TryBot: Ian Lance Taylor <iant@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org>
2017-03-24runtime: access _cgo_yield indirectlyCherry Zhang
The darwin linker for ARM does not allow PC-relative relocation of external symbol in text section. Work around it by accessing it indirectly: putting its address in a global variable (which is not external), and accessing through that variable. Fixes #19684. Change-Id: I41361bbb281b5dbdda0d100ae49d32c69ed85a81 Reviewed-on: https://go-review.googlesource.com/38596 Run-TryBot: Cherry Zhang <cherryyz@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org> Reviewed-by: Elias Naur <elias.naur@gmail.com>
2017-03-09runtime: fix _cgo_yield usage with sysmon and on BSDBryan C. Mills
There are a few problems from change 35494, discovered during testing of change 37852. 1. I was confused about the usage of n.key in the sema variant, so we were looping on the wrong condition. The error was not caught by the TryBots (presumably due to missing TSAN coverage in the BSD and darwin builders?). 2. The sysmon goroutine sometimes skips notetsleep entirely, using direct usleep syscalls instead. In that case, we were not calling _cgo_yield, leading to missed signals under TSAN. 3. Some notetsleep calls have long finite timeouts. They should be broken up into smaller chunks with a yield at the end of each chunk. updates #18717 Change-Id: I91175af5dea3857deebc686f51a8a40f9d690bcc Reviewed-on: https://go-review.googlesource.com/37867 Run-TryBot: Bryan Mills <bcmills@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
2017-03-08runtime: poll libc to deliver signals under TSANBryan C. Mills
fixes #18717 Change-Id: I7244463d2e7489e0b0fe3b74c4b782e71210beb2 Reviewed-on: https://go-review.googlesource.com/35494 Run-TryBot: Bryan Mills <bcmills@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
2016-04-14runtime: find a home for orphaned commentsJeremy Jackins
These comments were left behind after runtime.h was converted from C to Go. I examined the original code and tried to move these to the places that the most sense. Change-Id: I8769d60234c0113d682f9de3bd8d6c34c450c188 Reviewed-on: https://go-review.googlesource.com/21969 Reviewed-by: Matthew Dempsky <mdempsky@google.com> Run-TryBot: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org>
2016-03-02all: single space after period.Brad Fitzpatrick
The tree's pretty inconsistent about single space vs double space after a period in documentation. Make it consistently a single space, per earlier decisions. This means contributors won't be confused by misleading precedence. This CL doesn't use go/doc to parse. It only addresses // comments. It was generated with: $ perl -i -npe 's,^(\s*// .+[a-z]\.) +([A-Z]),$1 $2,' $(git grep -l -E '^\s*//(.+\.) +([A-Z])') $ go test go/doc -update Change-Id: Iccdb99c37c797ef1f804a94b22ba5ee4b500c4f7 Reviewed-on: https://go-review.googlesource.com/20022 Reviewed-by: Rob Pike <r@golang.org> Reviewed-by: Dave Day <djd@golang.org> Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org>
2015-11-10runtime: break atomics out into package runtime/internal/atomicMichael Matloob
This change breaks out most of the atomics functions in the runtime into package runtime/internal/atomic. It adds some basic support in the toolchain for runtime packages, and also modifies linux/arm atomics to remove the dependency on the runtime's mutex. The mutexes have been replaced with spinlocks. all trybots are happy! In addition to the trybots, I've tested on the darwin/arm64 builder, on the darwin/arm builder, and on a ppc64le machine. Change-Id: I6698c8e3cf3834f55ce5824059f44d00dc8e3c2f Reviewed-on: https://go-review.googlesource.com/14204 Run-TryBot: Michael Matloob <matloob@golang.org> Reviewed-by: Russ Cox <rsc@golang.org>
2015-07-27runtime: make notetsleep_internal nowritebarrierAustin Clements
When notetsleep_internal is called from notetsleepg, notetsleepg has just given up the P, so write barriers are not allowed in notetsleep_internal. Change-Id: I1b214fa388b1ea05b8ce2dcfe1c0074c0a3c8870 Reviewed-on: https://go-review.googlesource.com/12647 Reviewed-by: Rick Hudson <rlh@golang.org> Reviewed-by: Russ Cox <rsc@golang.org>
2015-02-02runtime: rename m.gcing to m.preemptoff and make it a stringAustin Clements
m.gcing has become overloaded to mean "don't preempt this g" in general. Once the garbage collector is preemptible, the one thing it *won't* mean is that we're in the garbage collector. So, rename gcing to "preemptoff" and make it a string giving a reason that preemption is disabled. gcing was never set to anything but 0 or 1, so we don't have to worry about there being a stack of reasons. Change-Id: I4337c29e8e942e7aa4f106fc29597e1b5de4ef46 Reviewed-on: https://go-review.googlesource.com/3660 Reviewed-by: Russ Cox <rsc@golang.org>
2015-01-05Revert "liblink, cmd/ld, runtime: remove stackguard1"Russ Cox
This reverts commit ab0535ae3fb45ba734d47542cc4845f27f708d1b. I think it will remain useful to distinguish code that must run on a system stack from code that can run on either stack, even if that distinction is no longer based on the implementation language. That is, I expect to add a //go:systemstack comment that, in terms of the old implementation, tells the compiler, to pretend this function was written in C. Change-Id: I33d2ebb2f99ae12496484c6ec8ed07233d693275 Reviewed-on: https://go-review.googlesource.com/2275 Reviewed-by: Russ Cox <rsc@golang.org>
2014-12-29liblink, cmd/ld, runtime: remove stackguard1Shenghou Ma
Now that we've removed all the C code in runtime and the C compilers, there is no need to have a separate stackguard field to check for C code on Go stack. Remove field g.stackguard1 and rename g.stackguard0 to g.stackguard. Adjust liblink and cmd/ld as necessary. Change-Id: I54e75db5a93d783e86af5ff1a6cd497d669d8d33 Reviewed-on: https://go-review.googlesource.com/2144 Reviewed-by: Keith Randall <khr@golang.org>
2014-12-28runtime: rename gothrow to throwKeith Randall
Rename "gothrow" to "throw" now that the C version of "throw" is no longer needed. This change is purely mechanical except in panic.go where the old version of "throw" has been deleted. sed -i "" 's/[[:<:]]gothrow[[:>:]]/throw/g' runtime/*.go Change-Id: Icf0752299c35958b92870a97111c67bcd9159dc3 Reviewed-on: https://go-review.googlesource.com/2150 Reviewed-by: Minux Ma <minux@golang.org> Reviewed-by: Dave Cheney <dave@cheney.net>
2014-11-11[dev.cc] runtime: convert scheduler from C to GoRuss Cox
The conversion was done with an automated tool and then modified only as necessary to make it compile and run. [This CL is part of the removal of C code from package runtime. See golang.org/s/dev.cc for an overview.] LGTM=r R=r, daniel.morsing CC=austin, dvyukov, golang-codereviews, iant, khr https://golang.org/cl/172260043
2014-09-08build: move package sources from src/pkg to srcRuss Cox
Preparation was in CL 134570043. This CL contains only the effect of 'hg mv src/pkg/* src'. For more about the move, see golang.org/s/go14nopkg.