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runtime: fix use of wrong g in gentraceback 

gentraceback gets the currently running g to do some sanity checks, but
should use gp everywhere to do its actual work. Some noncritical checks
later accidentally used g instead of gp. This seems like it could be a
problem in many different contexts, but I noticed in Windows profiling,
where profilem calls gentraceback on a goroutine from a different
thread.

Change-Id: I3da27a43e833b257f6411ee6893bdece45a9323f
Reviewed-on: https://go-review.googlesource.com/128895
Run-TryBot: Heschi Kreinick <heschi@google.com>
Reviewed-by: Austin Clements <austin@google.com>
This commit is contained in:
Heschi Kreinick 2018-08-17 16:32:02 -04:00
parent b15a1e3cfb
commit c9986d1452
1 changed files with 5 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
src/runtime/traceback.go
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@ -99,8 +99,9 @@ func gentraceback(pc0, sp0, lr0 uintptr, gp *g, skip int, pcbuf *uintptr, max in
if skip > 0 && callback != nil {
throw("gentraceback callback cannot be used with non-zero skip")
}
g := getg()
if g == gp && g == g.m.curg {
// Don't call this "g"; it's too easy get "g" and "gp" confused.
if ourg := getg(); ourg == gp && ourg == ourg.m.curg {
// The starting sp has been passed in as a uintptr, and the caller may
// have other uintptr-typed stack references as well.
// If during one of the calls that got us here or during one of the
@ -200,7 +201,7 @@ func gentraceback(pc0, sp0, lr0 uintptr, gp *g, skip int, pcbuf *uintptr, max in
// g0, this systemstack is at the top of the stack.
// if we're not on g0 or there's a no curg, then this is a regular call.
sp := frame.sp
if flags&_TraceJumpStack != 0 && f.funcID == funcID_systemstack && gp == g.m.g0 && gp.m.curg != nil {
if flags&_TraceJumpStack != 0 && f.funcID == funcID_systemstack && gp == gp.m.g0 && gp.m.curg != nil {
sp = gp.m.curg.sched.sp
frame.sp = sp
cgoCtxt = gp.m.curg.cgoCtxt
@ -425,7 +426,7 @@ func gentraceback(pc0, sp0, lr0 uintptr, gp *g, skip int, pcbuf *uintptr, max in
if frame.pc > f.entry {
print(" +", hex(frame.pc-f.entry))
}
if g.m.throwing > 0 && gp == g.m.curg || level >= 2 {
if gp.m != nil && gp.m.throwing > 0 && gp == gp.m.curg || level >= 2 {
print(" fp=", hex(frame.fp), " sp=", hex(frame.sp), " pc=", hex(frame.pc))
}
print("\n")