From ca56d576241c6783eb36eea526b42c4f3fbf697b Mon Sep 17 00:00:00 2001
From: Nikhil Benesch <nikhil.benesch@gmail.com>
Date: Tue, 13 Oct 2020 07:17:55 +0000
Subject: [PATCH] runtime: correct semaphore implementation on netbsd

NetBSD's semaphores use the underlying lighweight process mechanism
(LWP) on NetBSD, rather than pthreads. This means the m.prodcid needs
to be set to the LWP ID rather than the pthread ID in order for unpark
notifications to get sent to the right place.

Introduce a new getProcID() method that selects the correct ID for the
platform.

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/261742
---
 gcc/go/gofrontend/MERGE        |  2 +-
 libgo/go/runtime/os_aix.go     |  4 ++++
 libgo/go/runtime/os_gccgo.go   |  3 +--
 libgo/go/runtime/os_hurd.go    |  4 ++++
 libgo/go/runtime/os_linux.go   |  4 ++++
 libgo/go/runtime/os_netbsd.go  | 17 ++++++++++++-----
 libgo/go/runtime/os_solaris.go |  4 ++++
 7 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/gcc/go/gofrontend/MERGE b/gcc/go/gofrontend/MERGE
index 2c7a9bde825..c37df37db51 100644
--- a/gcc/go/gofrontend/MERGE
+++ b/gcc/go/gofrontend/MERGE
@@ -1,4 +1,4 @@
-6cb7b9e924d84125f21f4a2a96aa0d59466056fe
+c5505c4e626fa4217911443b4db8b065855a0206
 
 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/os_aix.go b/libgo/go/runtime/os_aix.go
index 951aeb6cffd..f49b83ccbe4 100644
--- a/libgo/go/runtime/os_aix.go
+++ b/libgo/go/runtime/os_aix.go
@@ -21,6 +21,10 @@ type mOS struct {
 	waitsema uintptr // semaphore for parking on locks
 }
 
+func getProcID() uint64 {
+	return uint64(gettid())
+}
+
 //extern malloc
 func libc_malloc(uintptr) unsafe.Pointer
 
diff --git a/libgo/go/runtime/os_gccgo.go b/libgo/go/runtime/os_gccgo.go
index ab190229860..a8859c085a3 100644
--- a/libgo/go/runtime/os_gccgo.go
+++ b/libgo/go/runtime/os_gccgo.go
@@ -27,8 +27,7 @@ func mpreinit(mp *m) {
 func minit() {
 	minitSignals()
 
-	// FIXME: only works on linux for now.
-	getg().m.procid = uint64(gettid())
+	getg().m.procid = getProcID()
 }
 
 // Called from dropm to undo the effect of an minit.
diff --git a/libgo/go/runtime/os_hurd.go b/libgo/go/runtime/os_hurd.go
index b3c6f8062ca..1613b410e2c 100644
--- a/libgo/go/runtime/os_hurd.go
+++ b/libgo/go/runtime/os_hurd.go
@@ -18,6 +18,10 @@ type mOS struct {
 	waitsema uintptr // semaphore for parking on locks
 }
 
+func getProcID() uint64 {
+	return uint64(gettid())
+}
+
 //extern malloc
 func libc_malloc(uintptr) unsafe.Pointer
 
diff --git a/libgo/go/runtime/os_linux.go b/libgo/go/runtime/os_linux.go
index 5d550646715..627b6d6d43c 100644
--- a/libgo/go/runtime/os_linux.go
+++ b/libgo/go/runtime/os_linux.go
@@ -13,6 +13,10 @@ type mOS struct {
 	unused byte
 }
 
+func getProcID() uint64 {
+	return uint64(gettid())
+}
+
 func futex(addr unsafe.Pointer, op int32, val uint32, ts, addr2 unsafe.Pointer, val3 uint32) int32 {
 	return int32(syscall(_SYS_futex, uintptr(addr), uintptr(op), uintptr(val), uintptr(ts), uintptr(addr2), uintptr(val3)))
 }
diff --git a/libgo/go/runtime/os_netbsd.go b/libgo/go/runtime/os_netbsd.go
index 69d2c710449..89a8d076f12 100644
--- a/libgo/go/runtime/os_netbsd.go
+++ b/libgo/go/runtime/os_netbsd.go
@@ -14,12 +14,19 @@ type mOS struct {
 	waitsemacount uint32
 }
 
+func getProcID() uint64 {
+	return uint64(lwp_self())
+}
+
+//extern _lwp_self
+func lwp_self() int32
+
 //go:noescape
-//extern lwp_park
+//extern _lwp_park
 func lwp_park(ts int32, rel int32, abstime *timespec, unpark int32, hint, unparkhint unsafe.Pointer) int32
 
 //go:noescape
-//extern lwp_unpark
+//extern _lwp_unpark
 func lwp_unpark(lwp int32, hint unsafe.Pointer) int32
 
 //go:noescape
@@ -88,7 +95,7 @@ func semasleep(ns int64) int32 {
 			tsp = &ts
 		}
 		ret := lwp_park(_CLOCK_MONOTONIC, _TIMER_RELTIME, tsp, 0, unsafe.Pointer(&_g_.m.waitsemacount), nil)
-		if ret == _ETIMEDOUT {
+		if ret != 0 && errno() == _ETIMEDOUT {
 			return -1
 		}
 	}
@@ -101,10 +108,10 @@ func semawakeup(mp *m) {
 	// "If the target LWP is not currently waiting, it will return
 	// immediately upon the next call to _lwp_park()."
 	ret := lwp_unpark(int32(mp.procid), unsafe.Pointer(&mp.waitsemacount))
-	if ret != 0 && ret != _ESRCH {
+	if ret != 0 && errno() != _ESRCH {
 		// semawakeup can be called on signal stack.
 		systemstack(func() {
-			print("thrwakeup addr=", &mp.waitsemacount, " sem=", mp.waitsemacount, " ret=", ret, "\n")
+			print("thrwakeup addr=", &mp.waitsemacount, " sem=", mp.waitsemacount, " errno=", errno(), "\n")
 		})
 	}
 }
diff --git a/libgo/go/runtime/os_solaris.go b/libgo/go/runtime/os_solaris.go
index 63b5cd70c8c..c568629e566 100644
--- a/libgo/go/runtime/os_solaris.go
+++ b/libgo/go/runtime/os_solaris.go
@@ -10,6 +10,10 @@ type mOS struct {
 	waitsema uintptr // semaphore for parking on locks
 }
 
+func getProcID() uint64 {
+	return uint64(gettid())
+}
+
 //extern malloc
 func libc_malloc(uintptr) unsafe.Pointer
 
-- 
2.30.2