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call_usermodehelper(): increase reliability

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Presently call_usermodehelper_setup() uses GFP_ATOMIC.  but it can return
NULL _very_ easily.

GFP_ATOMIC is needed only when we can't sleep.  and, GFP_KERNEL is robust
and better.

thus, I add gfp_mask argument to call_usermodehelper_setup().

So, its callers pass the gfp_t as below:

call_usermodehelper() and call_usermodehelper_keys():
	depend on 'wait' argument.
call_usermodehelper_pipe():
	always GFP_KERNEL because always run under process context.
orderly_poweroff():
	pass to GFP_ATOMIC because may run under interrupt context.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: "Paul Menage" <menage@google.com>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
KOSAKI Motohiro 2008-07-25 01:45:38 -07:00 committed by Linus Torvalds
parent f557d0996a
commit ac331d158e
3 changed files with 13 additions and 9 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

11
include/linux/kmod.h
View file

@ -19,6 +19,7 @@
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/ */
#include <linux/gfp.h>
#include <linux/stddef.h> #include <linux/stddef.h>
#include <linux/errno.h> #include <linux/errno.h>
#include <linux/compiler.h> #include <linux/compiler.h>
@ -41,8 +42,8 @@ struct file;
struct subprocess_info; struct subprocess_info;
/* Allocate a subprocess_info structure */ /* Allocate a subprocess_info structure */
struct subprocess_info *call_usermodehelper_setup(char *path, struct subprocess_info *call_usermodehelper_setup(char *path, char **argv,
char **argv, char **envp); char **envp, gfp_t gfp_mask);
/* Set various pieces of state into the subprocess_info structure */ /* Set various pieces of state into the subprocess_info structure */
void call_usermodehelper_setkeys(struct subprocess_info *info, void call_usermodehelper_setkeys(struct subprocess_info *info,
@ -69,8 +70,9 @@ static inline int
call_usermodehelper(char *path, char **argv, char **envp, enum umh_wait wait) call_usermodehelper(char *path, char **argv, char **envp, enum umh_wait wait)
{ {
struct subprocess_info *info; struct subprocess_info *info;
gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
info = call_usermodehelper_setup(path, argv, envp); info = call_usermodehelper_setup(path, argv, envp, gfp_mask);
if (info == NULL) if (info == NULL)
return -ENOMEM; return -ENOMEM;
return call_usermodehelper_exec(info, wait); return call_usermodehelper_exec(info, wait);
@ -81,8 +83,9 @@ call_usermodehelper_keys(char *path, char **argv, char **envp,
struct key *session_keyring, enum umh_wait wait) struct key *session_keyring, enum umh_wait wait)
{ {
struct subprocess_info *info; struct subprocess_info *info;
gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
info = call_usermodehelper_setup(path, argv, envp); info = call_usermodehelper_setup(path, argv, envp, gfp_mask);
if (info == NULL) if (info == NULL)
return -ENOMEM; return -ENOMEM;

9
kernel/kmod.c
View file

@ -352,16 +352,17 @@ static inline void register_pm_notifier_callback(void) {}
* @path: path to usermode executable * @path: path to usermode executable
* @argv: arg vector for process * @argv: arg vector for process
* @envp: environment for process * @envp: environment for process
* @gfp_mask: gfp mask for memory allocation
* *
* Returns either %NULL on allocation failure, or a subprocess_info * Returns either %NULL on allocation failure, or a subprocess_info
* structure. This should be passed to call_usermodehelper_exec to * structure. This should be passed to call_usermodehelper_exec to
* exec the process and free the structure. * exec the process and free the structure.
*/ */
struct subprocess_info *call_usermodehelper_setup(char *path, struct subprocess_info *call_usermodehelper_setup(char *path, char **argv,
char **argv, char **envp) char **envp, gfp_t gfp_mask)
{ {
struct subprocess_info *sub_info; struct subprocess_info *sub_info;
sub_info = kzalloc(sizeof(struct subprocess_info), GFP_ATOMIC); sub_info = kzalloc(sizeof(struct subprocess_info), gfp_mask);
if (!sub_info) if (!sub_info)
goto out; goto out;
@ -494,7 +495,7 @@ int call_usermodehelper_pipe(char *path, char **argv, char **envp,
struct subprocess_info *sub_info; struct subprocess_info *sub_info;
int ret; int ret;
sub_info = call_usermodehelper_setup(path, argv, envp); sub_info = call_usermodehelper_setup(path, argv, envp, GFP_KERNEL);
if (sub_info == NULL) if (sub_info == NULL)
return -ENOMEM; return -ENOMEM;

2
kernel/sys.c
View file

@ -1795,7 +1795,7 @@ int orderly_poweroff(bool force)
goto out; goto out;
} }
info = call_usermodehelper_setup(argv[0], argv, envp); info = call_usermodehelper_setup(argv[0], argv, envp, GFP_ATOMIC);
if (info == NULL) { if (info == NULL) {
argv_free(argv); argv_free(argv);
goto out; goto out;