runtime: split minit() to mpreinit() and minit()

mpreinit() is called on the parent thread and with mcache (can allocate memory),
minit() is called on the child thread and can not allocate memory.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/7389043

9 files changed, 68 insertions, 12 deletions

diff --git a/src/pkg/runtime/proc.c b/src/pkg/runtime/proc.c
index 67d6dad488..5c36ddf745 100644
--- a/src/pkg/runtime/proc.c
+++ b/src/pkg/runtime/proc.c
@@ -370,6 +370,8 @@ mcommoninit(M *mp)
 
 	runtime·callers(1, mp->createstack, nelem(mp->createstack));
 
+	runtime·mpreinit(mp);
+
 	// Add to runtime·allm so garbage collector doesn't free m
 	// when it is just in a register or thread-local storage.
 	mp->alllink = runtime·allm;
diff --git a/src/pkg/runtime/runtime.h b/src/pkg/runtime/runtime.h
index 8162874bbe..4ca7cc7dc9 100644
--- a/src/pkg/runtime/runtime.h
+++ b/src/pkg/runtime/runtime.h
@@ -660,6 +660,7 @@ int32	runtime·atoi(byte*);
 void	runtime·newosproc(M *mp, G *gp, void *stk, void (*fn)(void));
 G*	runtime·malg(int32);
 void	runtime·asminit(void);
+void	runtime·mpreinit(M*);
 void	runtime·minit(void);
 void	runtime·unminit(void);
 void	runtime·signalstack(byte*, int32);
diff --git a/src/pkg/runtime/thread_darwin.c b/src/pkg/runtime/thread_darwin.c
index 1d6037b48b..1a13eba1cd 100644
--- a/src/pkg/runtime/thread_darwin.c
+++ b/src/pkg/runtime/thread_darwin.c
@@ -109,12 +109,19 @@ runtime·newosproc(M *mp, G *gp, void *stk, void (*fn)(void))
 }
 
 // Called to initialize a new m (including the bootstrap m).
+// Called on the parent thread (main thread in case of bootstrap), can allocate memory.
+void
+runtime·mpreinit(M *mp)
+{
+	mp->gsignal = runtime·malg(32*1024);	// OS X wants >=8K, Linux >=2K
+}
+
+// Called to initialize a new m (including the bootstrap m).
+// Called on the new thread, can not allocate memory.
 void
 runtime·minit(void)
 {
 	// Initialize signal handling.
-	if(m->gsignal == nil)
-		m->gsignal = runtime·malg(32*1024);	// OS X wants >=8K, Linux >=2K
 	runtime·signalstack((byte*)m->gsignal->stackguard - StackGuard, 32*1024);
 
 	runtime·sigprocmask(SIG_SETMASK, &sigset_none, nil);
diff --git a/src/pkg/runtime/thread_freebsd.c b/src/pkg/runtime/thread_freebsd.c
index 4d5f69a9f3..d7758eaafb 100644
--- a/src/pkg/runtime/thread_freebsd.c
+++ b/src/pkg/runtime/thread_freebsd.c
@@ -121,11 +121,19 @@ runtime·goenvs(void)
 }
 
 // Called to initialize a new m (including the bootstrap m).
+// Called on the parent thread (main thread in case of bootstrap), can allocate memory.
+void
+runtime·mpreinit(M *mp)
+{
+	mp->gsignal = runtime·malg(32*1024);
+}
+
+// Called to initialize a new m (including the bootstrap m).
+// Called on the new thread, can not allocate memory.
 void
 runtime·minit(void)
 {
 	// Initialize signal handling
-	m->gsignal = runtime·malg(32*1024);
 	runtime·signalstack((byte*)m->gsignal->stackguard - StackGuard, 32*1024);
 	runtime·sigprocmask(&sigset_none, nil);
 }
diff --git a/src/pkg/runtime/thread_linux.c b/src/pkg/runtime/thread_linux.c
index 02a5eaee2f..85c3e6b8cf 100644
--- a/src/pkg/runtime/thread_linux.c
+++ b/src/pkg/runtime/thread_linux.c
@@ -171,12 +171,19 @@ runtime·goenvs(void)
 }
 
 // Called to initialize a new m (including the bootstrap m).
+// Called on the parent thread (main thread in case of bootstrap), can allocate memory.
+void
+runtime·mpreinit(M *mp)
+{
+	mp->gsignal = runtime·malg(32*1024);	// OS X wants >=8K, Linux >=2K
+}
+
+// Called to initialize a new m (including the bootstrap m).
+// Called on the new thread, can not allocate memory.
 void
 runtime·minit(void)
 {
 	// Initialize signal handling.
-	if(m->gsignal == nil)
-		m->gsignal = runtime·malg(32*1024);	// OS X wants >=8K, Linux >=2K
 	runtime·signalstack((byte*)m->gsignal->stackguard - StackGuard, 32*1024);
 	runtime·rtsigprocmask(SIG_SETMASK, &sigset_none, nil, sizeof(Sigset));
 }
diff --git a/src/pkg/runtime/thread_netbsd.c b/src/pkg/runtime/thread_netbsd.c
index ebef45e757..aba8fea7a2 100644
--- a/src/pkg/runtime/thread_netbsd.c
+++ b/src/pkg/runtime/thread_netbsd.c
@@ -187,14 +187,21 @@ runtime·goenvs(void)
 }
 
 // Called to initialize a new m (including the bootstrap m).
+// Called on the parent thread (main thread in case of bootstrap), can allocate memory.
+void
+runtime·mpreinit(M *mp)
+{
+	mp->gsignal = runtime·malg(32*1024);
+}
+
+// Called to initialize a new m (including the bootstrap m).
+// Called on the new thread, can not allocate memory.
 void
 runtime·minit(void)
 {
 	m->procid = runtime·lwp_self();
 
 	// Initialize signal handling
-	if(m->gsignal == nil)
-		m->gsignal = runtime·malg(32*1024);
 	runtime·signalstack((byte*)m->gsignal->stackguard - StackGuard, 32*1024);
 	runtime·sigprocmask(SIG_SETMASK, &sigset_none, nil);
 }
diff --git a/src/pkg/runtime/thread_openbsd.c b/src/pkg/runtime/thread_openbsd.c
index 8433e8bae5..525dc697e0 100644
--- a/src/pkg/runtime/thread_openbsd.c
+++ b/src/pkg/runtime/thread_openbsd.c
@@ -166,12 +166,19 @@ runtime·goenvs(void)
 }
 
 // Called to initialize a new m (including the bootstrap m).
+// Called on the parent thread (main thread in case of bootstrap), can allocate memory.
+void
+runtime·mpreinit(M *mp)
+{
+	mp->gsignal = runtime·malg(32*1024);
+}
+
+// Called to initialize a new m (including the bootstrap m).
+// Called on the new thread, can not allocate memory.
 void
 runtime·minit(void)
 {
 	// Initialize signal handling
-	if(m->gsignal == nil)
-		m->gsignal = runtime·malg(32*1024);
 	runtime·signalstack((byte*)m->gsignal->stackguard - StackGuard, 32*1024);
 	runtime·sigprocmask(SIG_SETMASK, sigset_none);
 }
diff --git a/src/pkg/runtime/thread_plan9.c b/src/pkg/runtime/thread_plan9.c
index bca0deac62..625c8b48d4 100644
--- a/src/pkg/runtime/thread_plan9.c
+++ b/src/pkg/runtime/thread_plan9.c
@@ -11,13 +11,21 @@ extern SigTab runtime·sigtab[];
 
 int32 runtime·postnote(int32, int8*);
 
+// Called to initialize a new m (including the bootstrap m).
+// Called on the parent thread (main thread in case of bootstrap), can allocate memory.
 void
-runtime·minit(void)
+runtime·mpreinit(M *mp)
 {
 	// Initialize stack and goroutine for note handling.
-	m->gsignal = runtime·malg(32*1024);
-	m->notesig = (int8*)runtime·malloc(ERRMAX*sizeof(int8));
+	mp->gsignal = runtime·malg(32*1024);
+	mp->notesig = (int8*)runtime·malloc(ERRMAX*sizeof(int8));
+}
 
+// Called to initialize a new m (including the bootstrap m).
+// Called on the new thread, can not allocate memory.
+void
+runtime·minit(void)
+{
 	// Mask all SSE floating-point exceptions
 	// when running on the 64-bit kernel.
 	runtime·setfpmasks();
diff --git a/src/pkg/runtime/thread_windows.c b/src/pkg/runtime/thread_windows.c
index 7110c6efe4..4d95e99870 100644
--- a/src/pkg/runtime/thread_windows.c
+++ b/src/pkg/runtime/thread_windows.c
@@ -206,6 +206,15 @@ runtime·newosproc(M *mp, G *gp, void *stk, void (*fn)(void))
 }
 
 // Called to initialize a new m (including the bootstrap m).
+// Called on the parent thread (main thread in case of bootstrap), can allocate memory.
+void
+runtime·mpreinit(M *mp)
+{
+	USED(mp);
+}
+
+// Called to initialize a new m (including the bootstrap m).
+// Called on the new thread, can not allocate memory.
 void
 runtime·minit(void)
 {