uml: simplify helper stack handling

run_helper and run_helper_thread had arguments which were the same in all
callers.  run_helper's stack_out was always NULL and run_helper_thread's
stack_order was always 0.  These are now gone, and the constants folded
into the code.

Also fixed leaks of the helper stack in the AIO and SIGIO code.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

5 files changed, 27 insertions, 26 deletions

diff --git a/arch/um/os-Linux/aio.c b/arch/um/os-Linux/aio.c
index 9bf944f6a1db..b126df4ea168 100644
--- a/arch/um/os-Linux/aio.c
+++ b/arch/um/os-Linux/aio.c
@@ -177,6 +177,7 @@ static int do_not_aio(struct aio_thread_req *req)
 static int aio_req_fd_r = -1;
 static int aio_req_fd_w = -1;
 static int aio_pid = -1;
+static unsigned long aio_stack;
 
 static int not_aio_thread(void *arg)
 {
@@ -212,7 +213,6 @@ static int not_aio_thread(void *arg)
 
 static int init_aio_24(void)
 {
-        unsigned long stack;
         int fds[2], err;
 
         err = os_pipe(fds, 1, 1);
@@ -227,7 +227,7 @@ static int init_aio_24(void)
                 goto out_close_pipe;
 
         err = run_helper_thread(not_aio_thread, NULL,
-                                CLONE_FILES | CLONE_VM | SIGCHLD, &stack, 0);
+                                CLONE_FILES | CLONE_VM | SIGCHLD, &aio_stack);
         if(err < 0)
                 goto out_close_pipe;
 
@@ -252,7 +252,6 @@ out:
 #define DEFAULT_24_AIO 0
 static int init_aio_26(void)
 {
-        unsigned long stack;
         int err;
 
         if(io_setup(256, &ctx)){
@@ -263,7 +262,7 @@ static int init_aio_26(void)
         }
 
         err = run_helper_thread(aio_thread, NULL,
-                                CLONE_FILES | CLONE_VM | SIGCHLD, &stack, 0);
+                                CLONE_FILES | CLONE_VM | SIGCHLD, &aio_stack);
         if(err < 0)
                 return err;
 
@@ -365,8 +364,10 @@ __initcall(init_aio);
 
 static void exit_aio(void)
 {
-        if(aio_pid != -1)
+        if (aio_pid != -1) {
                 os_kill_process(aio_pid, 1);
+                free_stack(aio_stack, 0);
+        }
 }
 
 __uml_exitcall(exit_aio);
diff --git a/arch/um/os-Linux/drivers/ethertap_user.c b/arch/um/os-Linux/drivers/ethertap_user.c
index acba30161287..cac01b31ea95 100644
--- a/arch/um/os-Linux/drivers/ethertap_user.c
+++ b/arch/um/os-Linux/drivers/ethertap_user.c
@@ -117,7 +117,7 @@ static int etap_tramp(char *dev, char *gate, int control_me,
         pe_data.control_remote = control_remote;
         pe_data.control_me = control_me;
         pe_data.data_me = data_me;
-        pid = run_helper(etap_pre_exec, &pe_data, args, NULL);
+        pid = run_helper(etap_pre_exec, &pe_data, args);
 
         if(pid < 0)
                 err = pid;
diff --git a/arch/um/os-Linux/drivers/tuntap_user.c b/arch/um/os-Linux/drivers/tuntap_user.c
index 11a9779dc9f1..f848b4ea9343 100644
--- a/arch/um/os-Linux/drivers/tuntap_user.c
+++ b/arch/um/os-Linux/drivers/tuntap_user.c
@@ -83,7 +83,7 @@ static int tuntap_open_tramp(char *gate, int *fd_out, int me, int remote,
         data.stdout = remote;
         data.close_me = me;
 
-        pid = run_helper(tuntap_pre_exec, &data, argv, NULL);
+        pid = run_helper(tuntap_pre_exec, &data, argv);
 
         if(pid < 0)
                 return -pid;
diff --git a/arch/um/os-Linux/helper.c b/arch/um/os-Linux/helper.c
index 97bed16bf4c7..9cf48d0577cc 100644
--- a/arch/um/os-Linux/helper.c
+++ b/arch/um/os-Linux/helper.c
@@ -44,17 +44,13 @@ static int helper_child(void *arg)
 /* 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, 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)
+int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv)
 {
         struct helper_data data;
         unsigned long stack, sp;
         int pid, fds[2], ret, n;
 
-        if ((stack_out != NULL) && (*stack_out != 0))
-                stack = *stack_out;
-        else
-                stack = alloc_stack(0, __cant_sleep());
+        stack = alloc_stack(0, __cant_sleep());
         if (stack == 0)
                 return -ENOMEM;
 
@@ -113,22 +109,21 @@ out_close:
                 close(fds[1]);
         close(fds[0]);
 out_free:
-        if ((stack_out == NULL) || (*stack_out == 0))
-                free_stack(stack, 0);
+        free_stack(stack, 0);
         return ret;
 }
 
 int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags,
-                      unsigned long *stack_out, int stack_order)
+                      unsigned long *stack_out)
 {
         unsigned long stack, sp;
         int pid, status, err;
 
-        stack = alloc_stack(stack_order, __cant_sleep());
+        stack = alloc_stack(0, __cant_sleep());
         if (stack == 0)
                 return -ENOMEM;
 
-        sp = stack + (UM_KERN_PAGE_SIZE << stack_order) - sizeof(void *);
+        sp = stack + UM_KERN_PAGE_SIZE - sizeof(void *);
         pid = clone(proc, (void *) sp, flags | SIGCHLD, arg);
         if (pid < 0) {
                 err = -errno;
@@ -147,7 +142,7 @@ int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags,
                 if (!WIFEXITED(status) || (WEXITSTATUS(status) != 0))
                         printk("run_helper_thread - thread returned status "
                                "0x%x\n", status);
-                free_stack(stack, stack_order);
+                free_stack(stack, 0);
         } else
                 *stack_out = stack;
         return pid;
diff --git a/arch/um/os-Linux/sigio.c b/arch/um/os-Linux/sigio.c
index 8d4e0c6b8c92..2c23cb261188 100644
--- a/arch/um/os-Linux/sigio.c
+++ b/arch/um/os-Linux/sigio.c
@@ -26,6 +26,7 @@
  * exitcall.
  */
 static int write_sigio_pid = -1;
+static unsigned long write_sigio_stack;
 
 /* These arrays are initialized before the sigio thread is started, and
  * the descriptors closed after it is killed.  So, it can't see them change.
@@ -144,8 +145,10 @@ static void update_thread(void)
         return;
  fail:
         /* Critical section start */
-        if(write_sigio_pid != -1)
+        if (write_sigio_pid != -1) {
                 os_kill_process(write_sigio_pid, 1);
+                free_stack(write_sigio_stack, 0);
+        }
         write_sigio_pid = -1;
         close(sigio_private[0]);
         close(sigio_private[1]);
@@ -243,7 +246,6 @@ static struct pollfd *setup_initial_poll(int fd)
 
 static void write_sigio_workaround(void)
 {
-        unsigned long stack;
         struct pollfd *p;
         int err;
         int l_write_sigio_fds[2];
@@ -293,7 +295,8 @@ static void write_sigio_workaround(void)
         memcpy(sigio_private, l_sigio_private, sizeof(l_sigio_private));
 
         write_sigio_pid = run_helper_thread(write_sigio_thread, NULL,
-                                            CLONE_FILES | CLONE_VM, &stack, 0);
+                                            CLONE_FILES | CLONE_VM,
+                                            &write_sigio_stack);
 
         if (write_sigio_pid < 0)
                 goto out_clear;
@@ -356,10 +359,12 @@ out:
 
 static void sigio_cleanup(void)
 {
-        if(write_sigio_pid != -1){
-                os_kill_process(write_sigio_pid, 1);
-                write_sigio_pid = -1;
-        }
+        if (write_sigio_pid == -1)
+                return;
+
+        os_kill_process(write_sigio_pid, 1);
+        free_stack(write_sigio_stack, 0);
+        write_sigio_pid = -1;
 }
 
 __uml_exitcall(sigio_cleanup);