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runtime: avoid staticinit dependency with sigsetAllExiting

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Currently, package runtime runs `osinit` before dynamic initialization
of package-scope variables; but on GOOS=linux, `osinit` involves
mutating `sigsetAllExiting`.

This currently works because cmd/compile and gccgo have
non-spec-conforming optimizations that statically initialize
`sigsetAllExiting`, but disabling that optimization causes
`sigsetAllExiting` to be dynamically initialized instead. This in turn
causes the mutations in `osinit` to get lost.

This CL moves the initialization of `sigsetAllExiting` from `osinit`
into its initialization expression, and then removes the special case
for continuing to perform the static-initialization optimization for
package runtime.

Updates #51913.

Change-Id: I3be31454277c103372c9701d227dc774b2311dad
Reviewed-on: https://go-review.googlesource.com/c/go/+/405549
Auto-Submit: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Heschi Kreinick <heschi@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
This commit is contained in:
Matthew Dempsky 2022-05-11 12:44:06 -07:00 committed by Gopher Robot
parent 3556d3b9bf
commit 1cdabf0c8b
2 changed files with 28 additions and 22 deletions
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18
src/runtime/os_linux.go
View File

@ -346,24 +346,6 @@ func getHugePageSize() uintptr {
func osinit() {
ncpu = getproccount()
physHugePageSize = getHugePageSize()
if iscgo {
// #42494 glibc and musl reserve some signals for
// internal use and require they not be blocked by
// the rest of a normal C runtime. When the go runtime
// blocks...unblocks signals, temporarily, the blocked
// interval of time is generally very short. As such,
// these expectations of *libc code are mostly met by
// the combined go+cgo system of threads. However,
// when go causes a thread to exit, via a return from
// mstart(), the combined runtime can deadlock if
// these signals are blocked. Thus, don't block these
// signals when exiting threads.
// - glibc: SIGCANCEL (32), SIGSETXID (33)
// - musl: SIGTIMER (32), SIGCANCEL (33), SIGSYNCCALL (34)
sigdelset(&sigsetAllExiting, 32)
sigdelset(&sigsetAllExiting, 33)
sigdelset(&sigsetAllExiting, 34)
}
osArchInit()
}

32
src/runtime/signal_unix.go
View File

@ -1177,10 +1177,34 @@ func msigrestore(sigmask sigset) {
}
// sigsetAllExiting is used by sigblock(true) when a thread is
// exiting. sigset_all is defined in OS specific code, and per GOOS
// behavior may override this default for sigsetAllExiting: see
// osinit().
var sigsetAllExiting = sigset_all
// exiting.
var sigsetAllExiting = func() sigset {
res := sigset_all
// Apply GOOS-specific overrides here, rather than in osinit,
// because osinit may be called before sigsetAllExiting is
// initialized (#51913).
if GOOS == "linux" && iscgo {
// #42494 glibc and musl reserve some signals for
// internal use and require they not be blocked by
// the rest of a normal C runtime. When the go runtime
// blocks...unblocks signals, temporarily, the blocked
// interval of time is generally very short. As such,
// these expectations of *libc code are mostly met by
// the combined go+cgo system of threads. However,
// when go causes a thread to exit, via a return from
// mstart(), the combined runtime can deadlock if
// these signals are blocked. Thus, don't block these
// signals when exiting threads.
// - glibc: SIGCANCEL (32), SIGSETXID (33)
// - musl: SIGTIMER (32), SIGCANCEL (33), SIGSYNCCALL (34)
sigdelset(&res, 32)
sigdelset(&res, 33)
sigdelset(&res, 34)
}
return res
}()
// sigblock blocks signals in the current thread's signal mask.
// This is used to block signals while setting up and tearing down g