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;
 }