[PATCH 4/5] UML - Simplify helper stack handling

Jeff Dike
2007-06-14T20:28:15Z

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>
--
arch/um/drivers/chan_user.c | 2 +-
arch/um/drivers/harddog_user.c | 2 +-
arch/um/drivers/net_user.c | 2 +-
arch/um/drivers/port_user.c | 2 +-
arch/um/drivers/slip_user.c | 2 +-
arch/um/drivers/slirp_user.c | 2 +-
arch/um/drivers/xterm.c | 2 +-
arch/um/include/os.h | 6 ++----
arch/um/os-Linux/aio.c | 11 ++++++-----
arch/um/os-Linux/drivers/ethertap_user.c | 2 +-
arch/um/os-Linux/drivers/tuntap_user.c | 2 +-
arch/um/os-Linux/helper.c | 19 +++++++------------
arch/um/os-Linux/sigio.c | 19 ++++++++++++-------
13 files changed, 36 insertions(+), 37 deletions(-)

Index: linux-2.6.21-mm/arch/um/drivers/harddog_user.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/drivers/harddog_user.c 2007-06-13 17:13:42.000000000 -0400
+++ linux-2.6.21-mm/arch/um/drivers/harddog_user.c 2007-06-13 18:44:41.000000000 -0400
@@ -68,7 +68,7 @@ int start_watchdog(int *in_fd_ret, int *
args = pid_args;
}

- pid = run_helper(pre_exec, &data, args, NULL);
+ pid = run_helper(pre_exec, &data, args);

os_close_file(out_fds[0]);
os_close_file(in_fds[1]);
Index: linux-2.6.21-mm/arch/um/drivers/net_user.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/drivers/net_user.c 2007-06-13 17:13:42.000000000 -0400
+++ linux-2.6.21-mm/arch/um/drivers/net_user.c 2007-06-14 11:20:36.000000000 -0400
@@ -187,7 +187,7 @@ static int change_tramp(char **argv, cha
}
pe_data.close_me = fds[0];
pe_data.stdout = fds[1];
- pid = run_helper(change_pre_exec, &pe_data, argv, NULL);
+ pid = run_helper(change_pre_exec, &pe_data, argv);

if (pid > 0) /* Avoid hang as we won't get data in failure case. */
read_output(fds[0], output, output_len);
Index: linux-2.6.21-mm/arch/um/drivers/port_user.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/drivers/port_user.c 2007-06-13 17:13:42.000000000 -0400
+++ linux-2.6.21-mm/arch/um/drivers/port_user.c 2007-06-14 11:20:36.000000000 -0400
@@ -188,7 +188,7 @@ int port_connection(int fd, int *socket,
{ .sock_fd = new,
.pipe_fd = socket[1] });

- err = run_helper(port_pre_exec, &data, argv, NULL);
+ err = run_helper(port_pre_exec, &data, argv);
if(err < 0)
goto out_shutdown;

Index: linux-2.6.21-mm/arch/um/drivers/slip_user.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/drivers/slip_user.c 2007-06-13 17:13:42.000000000 -0400
+++ linux-2.6.21-mm/arch/um/drivers/slip_user.c 2007-06-14 11:20:36.000000000 -0400
@@ -85,7 +85,7 @@ static int slip_tramp(char **argv, int f
pe_data.stdin = fd;
pe_data.stdout = fds[1];
pe_data.close_me = fds[0];
- err = run_helper(slip_pre_exec, &pe_data, argv, NULL);
+ err = run_helper(slip_pre_exec, &pe_data, argv);
if(err < 0)
goto out_close;
pid = err;
Index: linux-2.6.21-mm/arch/um/drivers/slirp_user.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/drivers/slirp_user.c 2007-06-13 17:13:42.000000000 -0400
+++ linux-2.6.21-mm/arch/um/drivers/slirp_user.c 2007-06-13 18:44:41.000000000 -0400
@@ -42,7 +42,7 @@ static int slirp_tramp(char **argv, int

pe_data.stdin = fd;
pe_data.stdout = fd;
- pid = run_helper(slirp_pre_exec, &pe_data, argv, NULL);
+ pid = run_helper(slirp_pre_exec, &pe_data, argv);

return(pid);
}
Index: linux-2.6.21-mm/arch/um/drivers/xterm.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/drivers/xterm.c 2007-06-13 17:13:42.000000000 -0400
+++ linux-2.6.21-mm/arch/um/drivers/xterm.c 2007-06-13 18:44:41.000000000 -0400
@@ -132,7 +132,7 @@ static int xterm_open(int input, int out
}

sprintf(title, data->title, data->device);
- pid = run_helper(NULL, NULL, argv, NULL);
+ pid = run_helper(NULL, NULL, argv);
if (pid < 0) {
err = pid;
printk(UM_KERN_ERR "xterm_open : run_helper failed, "
Index: linux-2.6.21-mm/arch/um/include/os.h
===================================================================
--- linux-2.6.21-mm.orig/arch/um/include/os.h 2007-06-13 17:13:42.000000000 -0400
+++ linux-2.6.21-mm/arch/um/include/os.h 2007-06-13 18:44:41.000000000 -0400
@@ -239,11 +239,9 @@ extern unsigned long __do_user_copy(void
/* execvp.c */
extern int execvp_noalloc(char *buf, const char *file, char *const argv[]);
/* helper.c */
-extern int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv,
- unsigned long *stack_out);
+extern int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv);
extern int run_helper_thread(int (*proc)(void *), void *arg,
- unsigned int flags, unsigned long *stack_out,
- int stack_order);
+ unsigned int flags, unsigned long *stack_out);
extern int helper_wait(int pid);

Index: linux-2.6.21-mm/arch/um/os-Linux/aio.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/os-Linux/aio.c 2007-06-13 17:13:42.000000000 -0400
+++ linux-2.6.21-mm/arch/um/os-Linux/aio.c 2007-06-13 18:44:41.000000000 -0400
@@ -177,6 +177,7 @@ static int do_not_aio(struct aio_thread_
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);
Index: linux-2.6.21-mm/arch/um/os-Linux/drivers/ethertap_user.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/os-Linux/drivers/ethertap_user.c 2007-06-13 17:13:42.000000000 -0400
+++ linux-2.6.21-mm/arch/um/os-Linux/drivers/ethertap_user.c 2007-06-14 11:20:36.000000000 -0400
@@ -117,7 +117,7 @@ static int etap_tramp(char *dev, char *g
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;
Index: linux-2.6.21-mm/arch/um/os-Linux/drivers/tuntap_user.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/os-Linux/drivers/tuntap_user.c 2007-06-13 17:13:42.000000000 -0400
+++ linux-2.6.21-mm/arch/um/os-Linux/drivers/tuntap_user.c 2007-06-13 18:44:41.000000000 -0400
@@ -83,7 +83,7 @@ static int tuntap_open_tramp(char *gate,
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;
Index: linux-2.6.21-mm/arch/um/os-Linux/helper.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/os-Linux/helper.c 2007-06-13 17:13:42.000000000 -0400
+++ linux-2.6.21-mm/arch/um/os-Linux/helper.c 2007-06-14 11:20:36.000000000 -0400
@@ -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 *
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;
Index: linux-2.6.21-mm/arch/um/os-Linux/sigio.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/os-Linux/sigio.c 2007-06-13 17:13:42.000000000 -0400
+++ linux-2.6.21-mm/arch/um/os-Linux/sigio.c 2007-06-14 11:20:36.000000000 -0400
@@ -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

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);
Index: linux-2.6.21-mm/arch/um/drivers/chan_user.c
===================================================================
--- linux-2.6.21-mm.orig/arch/um/drivers/chan_user.c 2007-06-13 18:44:36.000000000 -0400
+++ linux-2.6.21-mm/arch/um/drivers/chan_user.c 2007-06-13 18:44:41.000000000 -0400
@@ -161,7 +161,7 @@ static int winch_tramp(int fd, struct tt
* problem with /dev/net/tun, which if held open by this
* thread, prevents the TUN/TAP device from being reused.
*/
- err = run_helper_thread(winch_thread, &data, CLONE_FILES, stack_out, 0);
+ err = run_helper_thread(winch_thread, &data, CLONE_FILES, stack_out);
if(err < 0){
printk("fork of winch_thread failed - errno = %d\n", -err);
goto out_close;