// Copyright 2017 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package runtime
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import "unsafe"
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var labelSync uintptr
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//go:linkname runtime_setProfLabel runtime/pprof.runtime_setProfLabel
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func runtime_setProfLabel(labels unsafe.Pointer) {
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// Introduce race edge for read-back via profile.
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// This would more properly use &getg().labels as the sync address,
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// but we do the read in a signal handler and can't call the race runtime then.
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//
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// This uses racereleasemerge rather than just racerelease so
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// the acquire in profBuf.read synchronizes with *all* prior
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// setProfLabel operations, not just the most recent one. This
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// is important because profBuf.read will observe different
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// labels set by different setProfLabel operations on
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// different goroutines, so it needs to synchronize with all
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// of them (this wouldn't be an issue if we could synchronize
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// on &getg().labels since we would synchronize with each
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// most-recent labels write separately.)
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//
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// racereleasemerge is like a full read-modify-write on
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// labelSync, rather than just a store-release, so it carries
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// a dependency on the previous racereleasemerge, which
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// ultimately carries forward to the acquire in profBuf.read.
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if raceenabled {
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racereleasemerge(unsafe.Pointer(&labelSync))
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}
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getg().labels = labels
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}
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//go:linkname runtime_getProfLabel runtime/pprof.runtime_getProfLabel
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func runtime_getProfLabel() unsafe.Pointer {
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return getg().labels
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}
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