add LockOSThread and UnlockOSThread to

runtime package for use by debugger,
which needs to make sure that all ptrace calls
about a given pid come from the same thread.

R=r
DELTA=175  (90 added, 63 deleted, 22 changed)
OCL=31546
CL=31558

1 files changed, 14 insertions, 0 deletions

diff --git a/src/pkg/runtime/extern.go b/src/pkg/runtime/extern.go
index 6fb5756d6..1f6561394 100644
--- a/src/pkg/runtime/extern.go
+++ b/src/pkg/runtime/extern.go
@@ -26,3 +26,17 @@ func	Breakpoint()
 // program counter, file name, and line number within the file of the corresponding
 // call.  The boolean ok is false if it was not possible to recover the information.
 func	Caller(n int) (pc uintptr, file string, line int, ok bool)
+
+// mid returns the current os thread (m) id.
+func mid() uint32
+
+// LockOSThread wires the calling goroutine to its current operating system thread.
+// Until the calling goroutine exits or calls UnlockOSThread, it will always
+// execute in that thread, and no other goroutine can.
+// LockOSThread cannot be used during init functions.
+func LockOSThread()
+
+// UnlockOSThread unwires the calling goroutine from its fixed operating system thread.
+// If the calling goroutine has not called LockOSThread, UnlockOSThread is a no-op.
+func UnlockOSThread()
+