call_usermodehelper(): increase reliability

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>

1 files changed, 7 insertions, 4 deletions

diff --git a/include/linux/kmod.h b/include/linux/kmod.h
index 0509c4ce485..a1a91577813 100644
--- a/include/linux/kmod.h
+++ b/include/linux/kmod.h
@@ -19,6 +19,7 @@
  *      Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
+#include <linux/gfp.h>
 #include <linux/stddef.h>
 #include <linux/errno.h>
 #include <linux/compiler.h>
@@ -41,8 +42,8 @@ struct file;
 struct subprocess_info;
 
 /* Allocate a subprocess_info structure */
-struct subprocess_info *call_usermodehelper_setup(char *path,
-                                                  char **argv, char **envp);
+struct subprocess_info *call_usermodehelper_setup(char *path, char **argv,
+                                                  char **envp, gfp_t gfp_mask);
 
 /* Set various pieces of state into the subprocess_info structure */
 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)
 {
         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)
                 return -ENOMEM;
         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 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)
                 return -ENOMEM;