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| author | Matthew Dempsky <mdempsky@google.com> | 2021-08-05 13:05:23 -0700 |
|---|---|---|
| committer | Matthew Dempsky <mdempsky@google.com> | 2021-08-05 20:22:31 +0000 |
| commit | fd45e267c2f6ce7c6a88842e3ad94d3469223e42 (patch) | |
| tree | 0f721bdeb6a04dacbe298e6726c8bd09fe5af16d | |
| parent | 6e738868a7a943d7d4fd6bb1963e7f6d78111726 (diff) | |
| download | go-fd45e267c2f6ce7c6a88842e3ad94d3469223e42.tar.gz go-fd45e267c2f6ce7c6a88842e3ad94d3469223e42.zip | |
runtime: warn that KeepAlive is not an unsafe.Pointer workaround
Even experienced users occasionally mistake that runtime.KeepAlive can
be used as a workaround for following the unsafe.Pointer safety rules,
but it cannot. Add an explicit warning to this effect to dissuade
users from trying to use it as such.
Fixes #47562.
Change-Id: I842e33a3e1c080933c6b1bd1b6318448adbf495c
Reviewed-on: https://go-review.googlesource.com/c/go/+/340269
Trust: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
| -rw-r--r-- | src/runtime/mfinal.go | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/src/runtime/mfinal.go b/src/runtime/mfinal.go index fd318d49a8..c134a0f22d 100644 --- a/src/runtime/mfinal.go +++ b/src/runtime/mfinal.go @@ -466,6 +466,10 @@ okarg: // Without the KeepAlive call, the finalizer could run at the start of // syscall.Read, closing the file descriptor before syscall.Read makes // the actual system call. +// +// Note: KeepAlive should only be used to prevent finalizers from +// running prematurely. In particular, when used with unsafe.Pointer, +// the rules for valid uses of unsafe.Pointer still apply. func KeepAlive(x interface{}) { // Introduce a use of x that the compiler can't eliminate. // This makes sure x is alive on entry. We need x to be alive |