Revert "runtime/cgo: store M for C-created thread in pthread key"

This reverts CL 392854.

Reason for revert: caused #59294, which was derived from google
internal tests. The attempted fix of #59294 caused more breakage.

Change-Id: I5a061561ac2740856b7ecc09725ac28bd30f8bba
Reviewed-on: https://go-review.googlesource.com/c/go/+/481060
Reviewed-by: Heschi Kreinick <heschi@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

15 files changed, 0 insertions, 184 deletions

diff --git a/src/runtime/cgo/asm_386.s b/src/runtime/cgo/asm_386.s
index 086e20b02f..2e7e9512e2 100644
--- a/src/runtime/cgo/asm_386.s
+++ b/src/runtime/cgo/asm_386.s
@@ -4,14 +4,6 @@
 
 #include "textflag.h"
 
-// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
-// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
-TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
-	MOVL	_crosscall2_ptr(SB), AX
-	MOVL	$crosscall2(SB), BX
-	MOVL	BX, (AX)
-	RET
-
 // Called by C code generated by cmd/cgo.
 // func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
 // Saves C callee-saved registers and calls cgocallback with three arguments.
diff --git a/src/runtime/cgo/asm_amd64.s b/src/runtime/cgo/asm_amd64.s
index f254622f23..e223a6c870 100644
--- a/src/runtime/cgo/asm_amd64.s
+++ b/src/runtime/cgo/asm_amd64.s
@@ -5,14 +5,6 @@
 #include "textflag.h"
 #include "abi_amd64.h"
 
-// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
-// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
-TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
-	MOVQ	_crosscall2_ptr(SB), AX
-	MOVQ	$crosscall2(SB), BX
-	MOVQ	BX, (AX)
-	RET
-
 // Called by C code generated by cmd/cgo.
 // func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
 // Saves C callee-saved registers and calls cgocallback with three arguments.
diff --git a/src/runtime/cgo/asm_arm.s b/src/runtime/cgo/asm_arm.s
index f7f99772a6..ea55e173c1 100644
--- a/src/runtime/cgo/asm_arm.s
+++ b/src/runtime/cgo/asm_arm.s
@@ -4,14 +4,6 @@
 
 #include "textflag.h"
 
-// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
-// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
-TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
-	MOVW	_crosscall2_ptr(SB), R1
-	MOVW	$crosscall2(SB), R2
-	MOVW	R2, (R1)
-	RET
-
 // Called by C code generated by cmd/cgo.
 // func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
 // Saves C callee-saved registers and calls cgocallback with three arguments.
diff --git a/src/runtime/cgo/asm_arm64.s b/src/runtime/cgo/asm_arm64.s
index ce8909b492..e808dedcfc 100644
--- a/src/runtime/cgo/asm_arm64.s
+++ b/src/runtime/cgo/asm_arm64.s
@@ -5,14 +5,6 @@
 #include "textflag.h"
 #include "abi_arm64.h"
 
-// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
-// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
-TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
-	MOVD	_crosscall2_ptr(SB), R1
-	MOVD	$crosscall2(SB), R2
-	MOVD	R2, (R1)
-	RET
-
 // Called by C code generated by cmd/cgo.
 // func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
 // Saves C callee-saved registers and calls cgocallback with three arguments.
diff --git a/src/runtime/cgo/asm_loong64.s b/src/runtime/cgo/asm_loong64.s
index 3b514ffc4a..aea4f8e6b9 100644
--- a/src/runtime/cgo/asm_loong64.s
+++ b/src/runtime/cgo/asm_loong64.s
@@ -5,14 +5,6 @@
 #include "textflag.h"
 #include "abi_loong64.h"
 
-// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
-// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
-TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
-	MOVV	_crosscall2_ptr(SB), R5
-	MOVV	$crosscall2(SB), R6
-	MOVV	R6, (R5)
-	RET
-
 // Called by C code generated by cmd/cgo.
 // func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
 // Saves C callee-saved registers and calls cgocallback with three arguments.
diff --git a/src/runtime/cgo/asm_mips64x.s b/src/runtime/cgo/asm_mips64x.s
index 0a8fbbbef0..904f781d87 100644
--- a/src/runtime/cgo/asm_mips64x.s
+++ b/src/runtime/cgo/asm_mips64x.s
@@ -6,14 +6,6 @@
 
 #include "textflag.h"
 
-// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
-// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
-TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
-	MOVV	_crosscall2_ptr(SB), R5
-	MOVV	$crosscall2(SB), R6
-	MOVV	R6, (R5)
-	RET
-
 // Called by C code generated by cmd/cgo.
 // func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
 // Saves C callee-saved registers and calls cgocallback with three arguments.
diff --git a/src/runtime/cgo/asm_mipsx.s b/src/runtime/cgo/asm_mipsx.s
index a57ae97d7e..5e2db0b56e 100644
--- a/src/runtime/cgo/asm_mipsx.s
+++ b/src/runtime/cgo/asm_mipsx.s
@@ -6,14 +6,6 @@
 
 #include "textflag.h"
 
-// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
-// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
-TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
-	MOVW	_crosscall2_ptr(SB), R5
-	MOVW	$crosscall2(SB), R6
-	MOVW	R6, (R5)
-	RET
-
 // Called by C code generated by cmd/cgo.
 // func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
 // Saves C callee-saved registers and calls cgocallback with three arguments.
diff --git a/src/runtime/cgo/asm_ppc64x.s b/src/runtime/cgo/asm_ppc64x.s
index 8eb4a42157..fea749670b 100644
--- a/src/runtime/cgo/asm_ppc64x.s
+++ b/src/runtime/cgo/asm_ppc64x.s
@@ -7,26 +7,6 @@
 #include "textflag.h"
 #include "asm_ppc64x.h"
 
-// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
-// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
-TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
-	MOVD	_crosscall2_ptr(SB), R5
-#ifdef GOARCH_ppc64
-	MOVD	$_crosscall2<>(SB), R6
-#else
-	MOVD	$crosscall2(SB), R6
-#endif
-	MOVD	R6, (R5)
-	RET
-
-#ifdef GO_PPC64X_HAS_FUNCDESC
-// _crosscall2<> is a function descriptor to the real crosscall2.
-DATA    _crosscall2<>+0(SB)/8, $crosscall2(SB)
-DATA    _crosscall2<>+8(SB)/8, $TOC(SB)
-DATA    _crosscall2<>+16(SB)/8, $0
-GLOBL   _crosscall2<>(SB), NOPTR, $24
-#endif
-
 // Called by C code generated by cmd/cgo.
 // func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
 // Saves C callee-saved registers and calls cgocallback with three arguments.
@@ -52,12 +32,8 @@ TEXT crosscall2(SB),NOSPLIT|NOFRAME,$0
 
 #ifdef GO_PPC64X_HAS_FUNCDESC
 	// Load the real entry address from the first slot of the function descriptor.
-	// The first argument fn might be null, that means dropm in pthread key destructor.
-	CMP	R3, $0
-	BEQ	nil_fn
 	MOVD	8(R3), R2
 	MOVD	(R3), R3
-nil_fn:
 #endif
 	MOVD	R3, FIXED_FRAME+0(R1)	// fn unsafe.Pointer
 	MOVD	R4, FIXED_FRAME+8(R1)	// a unsafe.Pointer
diff --git a/src/runtime/cgo/asm_riscv64.s b/src/runtime/cgo/asm_riscv64.s
index 08c4ed8466..45151bf02b 100644
--- a/src/runtime/cgo/asm_riscv64.s
+++ b/src/runtime/cgo/asm_riscv64.s
@@ -4,14 +4,6 @@
 
 #include "textflag.h"
 
-// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
-// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
-TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
-	MOV	_crosscall2_ptr(SB), X7
-	MOV	$crosscall2(SB), X8
-	MOV	X8, (X7)
-	RET
-
 // Called by C code generated by cmd/cgo.
 // func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
 // Saves C callee-saved registers and calls cgocallback with three arguments.
diff --git a/src/runtime/cgo/asm_s390x.s b/src/runtime/cgo/asm_s390x.s
index bb0dfc1e31..8bf16e75e2 100644
--- a/src/runtime/cgo/asm_s390x.s
+++ b/src/runtime/cgo/asm_s390x.s
@@ -4,14 +4,6 @@
 
 #include "textflag.h"
 
-// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
-// It's such a pointer chain: _crosscall2_ptr -> x_crosscall2_ptr -> crosscall2
-TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
-	MOVD	_crosscall2_ptr(SB), R1
-	MOVD	$crosscall2(SB), R2
-	MOVD	R2, (R1)
-	RET
-
 // Called by C code generated by cmd/cgo.
 // func crosscall2(fn, a unsafe.Pointer, n int32, ctxt uintptr)
 // Saves C callee-saved registers and calls cgocallback with three arguments.
diff --git a/src/runtime/cgo/asm_wasm.s b/src/runtime/cgo/asm_wasm.s
index e7f01bdc56..cb140eb7b8 100644
--- a/src/runtime/cgo/asm_wasm.s
+++ b/src/runtime/cgo/asm_wasm.s
@@ -4,8 +4,5 @@
 
 #include "textflag.h"
 
-TEXT ·set_crosscall2(SB),NOSPLIT,$0-0
-	UNDEF
-
 TEXT crosscall2(SB), NOSPLIT, $0
 	UNDEF
diff --git a/src/runtime/cgo/callbacks.go b/src/runtime/cgo/callbacks.go
index 792dd7d086..e7c8ef3e07 100644
--- a/src/runtime/cgo/callbacks.go
+++ b/src/runtime/cgo/callbacks.go
@@ -71,42 +71,6 @@ var _cgo_thread_start = &x_cgo_thread_start
 var x_cgo_sys_thread_create byte
 var _cgo_sys_thread_create = &x_cgo_sys_thread_create
 
-// Indicates whether a dummy thread key has been created or not.
-//
-// When calling go exported function from C, we register a destructor
-// callback, for a dummy thread key, by using pthread_key_create.
-
-//go:cgo_import_static x_cgo_pthread_key_created
-//go:linkname x_cgo_pthread_key_created x_cgo_pthread_key_created
-//go:linkname _cgo_pthread_key_created _cgo_pthread_key_created
-var x_cgo_pthread_key_created byte
-var _cgo_pthread_key_created = &x_cgo_pthread_key_created
-
-// Export crosscall2 to a c function pointer variable.
-// Used to dropm in pthread key destructor, while C thread is exiting.
-
-//go:cgo_import_static x_crosscall2_ptr
-//go:linkname x_crosscall2_ptr x_crosscall2_ptr
-//go:linkname _crosscall2_ptr _crosscall2_ptr
-var x_crosscall2_ptr byte
-var _crosscall2_ptr = &x_crosscall2_ptr
-
-// Set the x_crosscall2_ptr C function pointer variable point to crosscall2.
-// It's for the runtime package to call at init time.
-func set_crosscall2()
-
-//go:linkname _set_crosscall2 runtime.set_crosscall2
-var _set_crosscall2 = set_crosscall2
-
-// Store the g into the thread-specific value.
-// So that pthread_key_destructor will dropm when the thread is exiting.
-
-//go:cgo_import_static x_cgo_bindm
-//go:linkname x_cgo_bindm x_cgo_bindm
-//go:linkname _cgo_bindm _cgo_bindm
-var x_cgo_bindm byte
-var _cgo_bindm = &x_cgo_bindm
-
 // Notifies that the runtime has been initialized.
 //
 // We currently block at every CGO entry point (via _cgo_wait_runtime_init_done)
diff --git a/src/runtime/cgo/gcc_libinit.c b/src/runtime/cgo/gcc_libinit.c
index 9676593211..57620fe4de 100644
--- a/src/runtime/cgo/gcc_libinit.c
+++ b/src/runtime/cgo/gcc_libinit.c
@@ -17,14 +17,6 @@ static pthread_cond_t runtime_init_cond = PTHREAD_COND_INITIALIZER;
 static pthread_mutex_t runtime_init_mu = PTHREAD_MUTEX_INITIALIZER;
 static int runtime_init_done;
 
-// pthread_g is a pthread specific key, for storing the g that binded to the C thread.
-// The registered pthread_key_destructor will dropm, when the pthread-specified value g is not NULL,
-// while a C thread is exiting.
-static pthread_key_t pthread_g;
-static void pthread_key_destructor(void* g);
-uintptr_t x_cgo_pthread_key_created;
-void (*x_crosscall2_ptr)(void (*fn)(void *), void *, int, size_t);
-
 // The context function, used when tracing back C calls into Go.
 static void (*cgo_context_function)(struct context_arg*);
 
@@ -47,12 +39,6 @@ _cgo_wait_runtime_init_done(void) {
 		pthread_cond_wait(&runtime_init_cond, &runtime_init_mu);
 	}
 
-	// The key and x_cgo_pthread_key_created are for the whole program,
-	// whereas the specific and destructor is per thread.
-	if (x_cgo_pthread_key_created == 0 && pthread_key_create(&pthread_g, pthread_key_destructor) == 0) {
-		x_cgo_pthread_key_created = 1;
-	}
-
 	// TODO(iant): For the case of a new C thread calling into Go, such
 	// as when using -buildmode=c-archive, we know that Go runtime
 	// initialization is complete but we do not know that all Go init
@@ -75,16 +61,6 @@ _cgo_wait_runtime_init_done(void) {
 	return 0;
 }
 
-// Store the g into a thread-specific value associated with the pthread key pthread_g.
-// And pthread_key_destructor will dropm when the thread is exiting.
-void x_cgo_bindm(void* g) {
-	// We assume this will always succeed, otherwise, there might be extra M leaking,
-	// when a C thread exits after a cgo call.
-	// We only invoke this function once per thread in runtime.needAndBindM,
-	// and the next calls just reuse the bound m.
-	pthread_setspecific(pthread_g, g);
-}
-
 void
 x_cgo_notify_runtime_init_done(void* dummy __attribute__ ((unused))) {
 	pthread_mutex_lock(&runtime_init_mu);
@@ -134,14 +110,3 @@ _cgo_try_pthread_create(pthread_t* thread, const pthread_attr_t* attr, void* (*p
 	}
 	return EAGAIN;
 }
-
-static void
-pthread_key_destructor(void* g) {
-	if (x_crosscall2_ptr != NULL) {
-		// fn == NULL means dropm.
-		// We restore g by using the stored g, before dropm in runtime.cgocallback,
-		// since the g stored in the TLS by Go might be cleared in some platforms,
-		// before this destructor invoked.
-		x_crosscall2_ptr(NULL, g, 0, 0);
-	}
-}
diff --git a/src/runtime/cgo/gcc_libinit_windows.c b/src/runtime/cgo/gcc_libinit_windows.c
index 9a8c65ea29..fdcf027424 100644
--- a/src/runtime/cgo/gcc_libinit_windows.c
+++ b/src/runtime/cgo/gcc_libinit_windows.c
@@ -30,9 +30,6 @@ static CRITICAL_SECTION runtime_init_cs;
 static HANDLE runtime_init_wait;
 static int runtime_init_done;
 
-uintptr_t x_cgo_pthread_key_created;
-void (*x_crosscall2_ptr)(void (*fn)(void *), void *, int, size_t);
-
 // Pre-initialize the runtime synchronization objects
 void
 _cgo_preinit_init() {
@@ -94,12 +91,6 @@ _cgo_wait_runtime_init_done(void) {
 	return 0;
 }
 
-// Should not be used since x_cgo_pthread_key_created will always be zero.
-void x_cgo_bindm(void* dummy) {
-	fprintf(stderr, "unexpected cgo_bindm on Windows\n");
-	abort();
-}
-
 void
 x_cgo_notify_runtime_init_done(void* dummy) {
 	 _cgo_maybe_run_preinit();
diff --git a/src/runtime/cgo/libcgo.h b/src/runtime/cgo/libcgo.h
index 04755f0f20..af4960e7e9 100644
--- a/src/runtime/cgo/libcgo.h
+++ b/src/runtime/cgo/libcgo.h
@@ -52,11 +52,6 @@ extern void (*_cgo_thread_start)(ThreadStart *ts);
 extern void (*_cgo_sys_thread_create)(void* (*func)(void*), void* arg);
 
 /*
- * Indicates whether a dummy pthread per-thread variable is allocated.
- */
-extern uintptr_t *_cgo_pthread_key_created;
-
-/*
  * Creates the new operating system thread (OS, arch dependent).
  */
 void _cgo_sys_thread_start(ThreadStart *ts);