From a282a875c8856b024b51b8c643d080a6ea2dd8ab Mon Sep 17 00:00:00 2001 From: Ian Lance Taylor Date: Mon, 12 Jun 2017 23:14:05 +0000 Subject: [PATCH] runtime: ignore _Gscan bit when checking status in CgocallDone Also always access the atomicstatus field atomically. The effect of not checking the _Gscan bit is that if the GC decides to scan the stack just as the goroutine is leaving the system call, the goroutine might fail to call exitsyscall. Then then typically causes a runtime assertion failure later on. If we do call exitsyscall as we should, it will stall (in casgstatus) until the _Gscan bit is cleared. No separate test. I've observed causing sporadic failures running the misc/cgo tests, but we don't currently have a way to run those routinely for gccgo. I should fix that. Reviewed-on: https://go-review.googlesource.com/45392 From-SVN: r249138 --- gcc/go/gofrontend/MERGE | 2 +- libgo/go/runtime/cgo_gccgo.go | 2 +- libgo/go/runtime/proc.go | 2 +- 3 files changed, 3 insertions(+), 3 deletions(-) diff --git a/gcc/go/gofrontend/MERGE b/gcc/go/gofrontend/MERGE index aebab77b1d3..d4a312908f0 100644 --- a/gcc/go/gofrontend/MERGE +++ b/gcc/go/gofrontend/MERGE @@ -1,4 +1,4 @@ -61222d34c1b33a369bd86008a0541455dd17727e +908fc7e46ebe36658ed86b65a3d165fccb2e8576 The first line of this file holds the git revision number of the last merge done from the gofrontend repository. diff --git a/libgo/go/runtime/cgo_gccgo.go b/libgo/go/runtime/cgo_gccgo.go index a55fb436bc5..b0ad2f12a63 100644 --- a/libgo/go/runtime/cgo_gccgo.go +++ b/libgo/go/runtime/cgo_gccgo.go @@ -54,7 +54,7 @@ func CgocallDone() { // If we are invoked because the C function called _cgo_panic, // then _cgo_panic will already have exited syscall mode. - if gp.atomicstatus == _Gsyscall { + if readgstatus(gp)&^_Gscan == _Gsyscall { exitsyscall(0) } diff --git a/libgo/go/runtime/proc.go b/libgo/go/runtime/proc.go index 64735e2a653..038f20e977e 100644 --- a/libgo/go/runtime/proc.go +++ b/libgo/go/runtime/proc.go @@ -1459,7 +1459,7 @@ func dropm() { // gccgo sets the stack to Gdead here, because the splitstack // context is not initialized. - mp.curg.atomicstatus = _Gdead + atomic.Store(&mp.curg.atomicstatus, _Gdead) mp.curg.gcstack = nil mp.curg.gcnextsp = nil -- 2.30.2