6c13a1db2e
Calling cgocallback from a signal handler can fail when using the race detector. Calling cgocallback will lead to a call to newextram which will call oneNewExtraM which will call racegostart. The racegostart function will set up some race detector data structures, and doing that will sometimes call the C memory allocator. If we are running the signal handler from a signal that interrupted the C memory allocator, we will crash or hang. Instead, change the signal handler code to call needm and dropm. The needm function will grab allocated m and g structures and initialize the g to use the current stack--the signal stack. That is all we need to safely call code that allocates memory and checks whether it needs to split the stack. This may temporarily leave us with no m available to run a cgo callback, but that is OK in this case since the code we call will quickly either crash or call dropm to return the m. Implementing this required changing some of the setSignalstackSP functions to avoid a write barrier. These functions never need a write barrier but in some cases generated one anyhow because on some systems the ss_sp field is a pointer. Change-Id: I3893f47c3a66278f85eab7f94c1ab11d4f3be133 Reviewed-on: https://go-review.googlesource.com/30218 Run-TryBot: Ian Lance Taylor <iant@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> |
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The Go Programming Language
Go is an open source programming language that makes it easy to build simple, reliable, and efficient software.
For documentation about how to install and use Go, visit https://golang.org/ or load doc/install-source.html in your web browser.
Our canonical Git repository is located at https://go.googlesource.com/go. There is a mirror of the repository at https://github.com/golang/go.
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--
Binary Distribution Notes
If you have just untarred a binary Go distribution, you need to set the environment variable $GOROOT to the full path of the go directory (the one containing this file). You can omit the variable if you unpack it into /usr/local/go, or if you rebuild from sources by running all.bash (see doc/install-source.html). You should also add the Go binary directory $GOROOT/bin to your shell's path.
For example, if you extracted the tar file into $HOME/go, you might put the following in your .profile:
export GOROOT=$HOME/go
export PATH=$PATH:$GOROOT/bin
See https://golang.org/doc/install or doc/install.html for more details.