Revert "OS-6467 LX go 1.9 aborts on unexpected signal interpositioning"166

This reverts commit b036e0fd770de1dd266db82dad196891746e92e1.

4 files changed, 15 insertions, 55 deletions

diff --git a/usr/src/lib/brand/lx/lx_brand/common/clone.c b/usr/src/lib/brand/lx/lx_brand/common/clone.c
index 109baf3d0a..f8d5d9cd02 100644
--- a/usr/src/lib/brand/lx/lx_brand/common/clone.c
+++ b/usr/src/lib/brand/lx/lx_brand/common/clone.c
@@ -391,23 +391,8 @@ lx_clone(uintptr_t p1, uintptr_t p2, uintptr_t p3, uintptr_t p4, uintptr_t p5)
 		/*
 		 * Suspend signal delivery, run the stack management prefork
 		 * handler and perform the actual fork(2) operation.
-		 *
-		 * During vfork, Linux will not deliver any signals to any
-		 * thread in the parent. Some applications (e.g. Go) depend on
-		 * this. For example, we must prevent the following sequence:
-		 * 1) Parent with many threads, one thread calls vfork
-		 * 2) vforked child resets all signal handlers
-		 * 3) a different child of the parent exits and SIGCHLD is sent
-		 *    to parent before the vforked child execs/exits
-		 * The parent cannot receive the SIGCHLD until afer we repair
-		 * the parent's signal handlers in lx_sighandlers_restore, once
-		 * the parent resumes after the vfork.
 		 */
-		if (flags & LX_CLONE_VFORK) {
-			lx_block_all_signals();
-		} else {
-			_sigoff();
-		}
+		_sigoff();
 		lx_stack_prefork();
 		if (flags & LX_CLONE_VFORK) {
 			lx_sighandlers_t saved;
@@ -459,20 +444,16 @@ lx_clone(uintptr_t p1, uintptr_t p2, uintptr_t p3, uintptr_t p4, uintptr_t p5)
 				(void) uucopy(&rval, ptidp, sizeof (int));
 			}
 
-			/*
-			 * Re-enable signal delivery in the parent process.
-			 */
-			if (flags & LX_CLONE_VFORK) {
-				lx_unblock_all_signals();
-			} else {
-				_sigon();
-			}
-
 			if (rval > 0) {
 				lx_ptrace_stop_if_option(ptrace_event, B_FALSE,
 				    (ulong_t)rval, NULL);
 			}
 
+			/*
+			 * Re-enable signal delivery in the parent process.
+			 */
+			_sigon();
+
 			return ((rval < 0) ? -errno : rval);
 		}
 
@@ -581,18 +562,14 @@ lx_clone(uintptr_t p1, uintptr_t p2, uintptr_t p3, uintptr_t p4, uintptr_t p5)
 		}
 
 		/*
-		 * Re-enable signal delivery in the child process.
+		 * Stop for ptrace if required.
 		 */
-		if (flags & LX_CLONE_VFORK) {
-			lx_unblock_all_signals();
-		} else {
-			_sigon();
-		}
+		lx_ptrace_stop_if_option(ptrace_event, B_TRUE, 0, NULL);
 
 		/*
-		 * Stop for ptrace if required.
+		 * Re-enable signal delivery in the child process.
 		 */
-		lx_ptrace_stop_if_option(ptrace_event, B_TRUE, 0, NULL);
+		_sigon();
 
 		/*
 		 * The child process returns via the regular emulated system
diff --git a/usr/src/lib/brand/lx/lx_brand/common/fork.c b/usr/src/lib/brand/lx/lx_brand/common/fork.c
index beb76fcf59..aa14267185 100644
--- a/usr/src/lib/brand/lx/lx_brand/common/fork.c
+++ b/usr/src/lib/brand/lx/lx_brand/common/fork.c
@@ -22,7 +22,7 @@
 /*
  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
- * Copyright 2017 Joyent, Inc.
+ * Copyright 2016 Joyent, Inc.  All rights reserved.
  */
 
 #include <errno.h>
@@ -124,7 +124,7 @@ lx_vfork(void)
 	 * the comments in lx_clone for more detail.
 	 */
 
-	lx_block_all_signals();
+	_sigoff();
 	lx_stack_prefork();
 	lx_sighandlers_save(&saved);
 	lx_tsd->lxtsd_is_vforked++;
@@ -138,7 +138,7 @@ lx_vfork(void)
 	switch (ret) {
 	case -1:
 		lx_stack_postfork();
-		lx_unblock_all_signals();
+		_sigon();
 		return (-errno);
 
 	case 0:
@@ -158,8 +158,6 @@ lx_vfork(void)
 		lx_debug("\tvfork native stack sp %p",
 		    vforkuc.uc_brand_data[1]);
 
-		lx_unblock_all_signals();
-
 		/* Stop for ptrace if required. */
 		lx_ptrace_stop_if_option(LX_PTRACE_O_TRACEVFORK, B_TRUE, 0,
 		    NULL);
@@ -178,9 +176,9 @@ lx_vfork(void)
 	default:
 		/* parent - child should have exited or exec-ed by now */
 		lx_stack_postfork();
-		lx_unblock_all_signals();
 		lx_ptrace_stop_if_option(LX_PTRACE_O_TRACEVFORK, B_FALSE,
 		    (ulong_t)ret, NULL);
+		_sigon();
 		return (ret);
 	}
 }
diff --git a/usr/src/lib/brand/lx/lx_brand/common/signal.c b/usr/src/lib/brand/lx/lx_brand/common/signal.c
index a8e3601cb9..c46d8b44ec 100644
--- a/usr/src/lib/brand/lx/lx_brand/common/signal.c
+++ b/usr/src/lib/brand/lx/lx_brand/common/signal.c
@@ -2378,15 +2378,3 @@ lx_signalfd4(int fd, uintptr_t mask, size_t msize, int flags)
 
 	return (r == -1 ? -errno : r);
 }
-
-void
-lx_block_all_signals()
-{
-	(void) syscall(SYS_brand, B_BLOCK_ALL_SIGS);
-}
-
-void
-lx_unblock_all_signals()
-{
-	(void) syscall(SYS_brand, B_UNBLOCK_ALL_SIGS);
-}
diff --git a/usr/src/lib/brand/lx/lx_brand/sys/lx_misc.h b/usr/src/lib/brand/lx/lx_brand/sys/lx_misc.h
index ce241db8bc..5879311cef 100644
--- a/usr/src/lib/brand/lx/lx_brand/sys/lx_misc.h
+++ b/usr/src/lib/brand/lx/lx_brand/sys/lx_misc.h
@@ -25,7 +25,7 @@
  */
 
 /*
- * Copyright 2017 Joyent, Inc.
+ * Copyright 2016 Joyent, Inc.  All rights reserved.
  */
 
 #ifndef _SYS_LX_H
@@ -147,9 +147,6 @@ extern void lx_free_other_stacks(void);
 extern void lx_stack_prefork(void);
 extern void lx_stack_postfork(void);
 
-extern void lx_block_all_signals();
-extern void lx_unblock_all_signals();
-
 /*
  * NO_UUCOPY disables calls to the uucopy* system calls to help with
  * debugging brand library accesses to linux application memory.