Merge branch 'upstream-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/linvil...

[pandora-kernel.git] / arch / um / os-Linux / helper.c

diff --git a/arch/um/os-Linux/helper.c b/arch/um/os-Linux/helper.c
index 6490a4f..d13299c 100644 (file)
--- 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("execvp of '%s' failed - errno = %d\n", argv[0], errno);
+       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)
-               return(-ENOMEM);
+       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;
@@ -92,19 +94,19 @@ int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv,
        close(fds[1]);
        fds[1] = -1;
 
-       /*Read the errno value from the child.*/
+       /* 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){
-               printk("run_helper : read on pipe failed, ret = %d\n", -n);
-               ret = n;
-               kill(pid, SIGKILL);
-               CATCH_EINTR(waitpid(pid, NULL, 0));
-       }
-       else if(n != 0){
-               CATCH_EINTR(n = waitpid(pid, NULL, 0));
-               ret = -errno;
-       } else {
+       if (n == 0) {
                ret = pid;
+       } else {
+               if (n < 0) {
+                       printk("run_helper : read on pipe failed, ret = %d\n",
+                              -n);
+                       ret = n;
+                       kill(pid, SIGKILL);
+               }
+               CATCH_EINTR(waitpid(pid, NULL, 0));
        }
 
 out_close:
@@ -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;
 }