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SubjectRe: [PATCH] call_usermodehelper() increase reliability
KOSAKI Motohiro wrote:
> Now, 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 caller pass 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>
> CC: Li Zefan <lizf@cn.fujitsu.com>
> CC: Jeremy Fitzhardinge <jeremy@xensource.com>
> CC: Rusty Russell <rusty@rustcorp.com.au>
> CC: Andi Kleen <andi@firstfloor.org>
>

Yes, looks good.

Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

> ---
> include/linux/kmod.h | 11 +++++++----
> kernel/kmod.c | 9 +++++----
> kernel/sys.c | 2 +-
> 3 files changed, 13 insertions(+), 9 deletions(-)
>
> Index: b/kernel/kmod.c
> ===================================================================
> --- a/kernel/kmod.c
> +++ b/kernel/kmod.c
> @@ -352,16 +352,17 @@ static inline void register_pm_notifier_
> * @path: path to usermode executable
> * @argv: arg vector for process
> * @envp: environment for process
> + * @gfp_mask: gfp mask for memory allocation
> *
> * Returns either %NULL on allocation failure, or a subprocess_info
> * structure. This should be passed to call_usermodehelper_exec to
> * exec the process and free the 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)
> {
> 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)
> goto out;
>
> @@ -494,7 +495,7 @@ int call_usermodehelper_pipe(char *path,
> struct subprocess_info *sub_info;
> int ret;
>
> - sub_info = call_usermodehelper_setup(path, argv, envp);
> + sub_info = call_usermodehelper_setup(path, argv, envp, GFP_KERNEL);
> if (sub_info == NULL)
> return -ENOMEM;
>
> Index: b/include/linux/kmod.h
> ===================================================================
> --- 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>
> @@ -40,8 +41,8 @@ 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,
> @@ -68,8 +69,9 @@ 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);
> @@ -80,8 +82,9 @@ call_usermodehelper_keys(char *path, cha
> 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;
>
> Index: b/kernel/sys.c
> ===================================================================
> --- a/kernel/sys.c
> +++ b/kernel/sys.c
> @@ -1795,7 +1795,7 @@ int orderly_poweroff(bool force)
> goto out;
> }
>
> - info = call_usermodehelper_setup(argv[0], argv, envp);
> + info = call_usermodehelper_setup(argv[0], argv, envp, GFP_ATOMIC);
> if (info == NULL) {
> argv_free(argv);
> goto out;
>
>
> --
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