1 files changed, 28 insertions, 26 deletions

diff --git a/arch/um/os-Linux/helper.c b/arch/um/os-Linux/helper.c
index cd15b9df5b5c..d13299cfa318 100644
--- a/arch/um/os-Linux/helper.c
+++ b/arch/um/os-Linux/helper.c
@@ -35,22 +35,23 @@ static int helper_child(void *arg)
 	char **argv = data->argv;
 	int errval;
 
-	if(helper_pause){
+	if (helper_pause){
 		signal(SIGHUP, helper_hup);
 		pause();
 	}
-	if(data->pre_exec != NULL)
+	if (data->pre_exec != NULL)
 		(*data->pre_exec)(data->pre_data);
 	execvp(argv[0], argv);
 	errval = -errno;
 	printk("helper_child - execve of '%s' failed - errno = %d\n", argv[0], errno);
 	os_write_file(data->fd, &errval, sizeof(errval));
 	kill(os_getpid(), SIGKILL);
-	return(0);
+	return 0;
 }
 
 /* Returns either the pid of the child process we run or -E* on failure.
- * XXX The alloc_stack here breaks if this is called in the tracing thread */
+ * XXX The alloc_stack here breaks if this is called in the tracing thread, so
+ * we need to receive a preallocated stack (a local buffer is ok). */
 int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv,
 	       unsigned long *stack_out)
 {
@@ -58,20 +59,21 @@ int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv,
 	unsigned long stack, sp;
 	int pid, fds[2], ret, n;
 
-	if((stack_out != NULL) && (*stack_out != 0))
+	if ((stack_out != NULL) && (*stack_out != 0))
 		stack = *stack_out;
-	else stack = alloc_stack(0, __cant_sleep());
-	if(stack == 0)
+	else
+		stack = alloc_stack(0, __cant_sleep());
+	if (stack == 0)
 		return -ENOMEM;
 
 	ret = os_pipe(fds, 1, 0);
-	if(ret < 0){
+	if (ret < 0) {
 		printk("run_helper : pipe failed, ret = %d\n", -ret);
 		goto out_free;
 	}
 
 	ret = os_set_exec_close(fds[1], 1);
-	if(ret < 0){
+	if (ret < 0) {
 		printk("run_helper : setting FD_CLOEXEC failed, ret = %d\n",
 		       -ret);
 		goto out_close;
@@ -83,7 +85,7 @@ int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv,
 	data.argv = argv;
 	data.fd = fds[1];
 	pid = clone(helper_child, (void *) sp, CLONE_VM | SIGCHLD, &data);
-	if(pid < 0){
+	if (pid < 0) {
 		ret = -errno;
 		printk("run_helper : clone failed, errno = %d\n", errno);
 		goto out_close;
@@ -95,10 +97,10 @@ int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv,
 	/* Read the errno value from the child, if the exec failed, or get 0 if
 	 * the exec succeeded because the pipe fd was set as close-on-exec. */
 	n = os_read_file(fds[0], &ret, sizeof(ret));
-	if(n == 0)
+	if (n == 0) {
 		ret = pid;
-	else {
-		if(n < 0){
+	} else {
+		if (n < 0) {
 			printk("run_helper : read on pipe failed, ret = %d\n",
 			       -n);
 			ret = n;
@@ -112,10 +114,9 @@ out_close:
 		close(fds[1]);
 	close(fds[0]);
 out_free:
-	if(stack_out == NULL)
+	if ((stack_out == NULL) || (*stack_out == 0))
 		free_stack(stack, 0);
-	else *stack_out = stack;
-	return(ret);
+	return ret;
 }
 
 int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags,
@@ -125,31 +126,32 @@ int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags,
 	int pid, status, err;
 
 	stack = alloc_stack(stack_order, __cant_sleep());
-	if(stack == 0) return(-ENOMEM);
+	if (stack == 0)
+		return -ENOMEM;
 
 	sp = stack + (page_size() << stack_order) - sizeof(void *);
 	pid = clone(proc, (void *) sp, flags | SIGCHLD, arg);
-	if(pid < 0){
+	if (pid < 0) {
 		err = -errno;
 		printk("run_helper_thread : clone failed, errno = %d\n",
 		       errno);
 		return err;
 	}
-	if(stack_out == NULL){
+	if (stack_out == NULL) {
 		CATCH_EINTR(pid = waitpid(pid, &status, 0));
-		if(pid < 0){
+		if (pid < 0) {
 			err = -errno;
 			printk("run_helper_thread - wait failed, errno = %d\n",
 			       errno);
 			pid = err;
 		}
-		if(!WIFEXITED(status) || (WEXITSTATUS(status) != 0))
+		if (!WIFEXITED(status) || (WEXITSTATUS(status) != 0))
 			printk("run_helper_thread - thread returned status "
 			       "0x%x\n", status);
 		free_stack(stack, stack_order);
-	}
-	else *stack_out = stack;
-	return(pid);
+	} else
+		*stack_out = stack;
+	return pid;
 }
 
 int helper_wait(int pid)
@@ -157,9 +159,9 @@ int helper_wait(int pid)
 	int ret;
 
 	CATCH_EINTR(ret = waitpid(pid, NULL, WNOHANG));
-	if(ret < 0){
+	if (ret < 0) {
 		ret = -errno;
 		printk("helper_wait : waitpid failed, errno = %d\n", errno);
 	}
-	return(ret);
+	return ret;
 }