diff --git a/include/linux/kmod.h b/include/linux/kmod.h index 722f477c4ef7..1b5985855ffc 100644 --- a/include/linux/kmod.h +++ b/include/linux/kmod.h @@ -54,6 +54,8 @@ enum umh_wait { UMH_WAIT_PROC = 1, /* wait for the process to complete */ }; +#define UMH_KILLABLE 4 /* wait for EXEC/PROC killable */ + struct subprocess_info { struct work_struct work; struct completion *complete; diff --git a/kernel/kmod.c b/kernel/kmod.c index 8ea25944ce33..f92f917c450c 100644 --- a/kernel/kmod.c +++ b/kernel/kmod.c @@ -201,7 +201,15 @@ EXPORT_SYMBOL(call_usermodehelper_freeinfo); static void umh_complete(struct subprocess_info *sub_info) { - complete(sub_info->complete); + struct completion *comp = xchg(&sub_info->complete, NULL); + /* + * See call_usermodehelper_exec(). If xchg() returns NULL + * we own sub_info, the UMH_KILLABLE caller has gone away. + */ + if (comp) + complete(comp); + else + call_usermodehelper_freeinfo(sub_info); } /* Keventd can't block, but this (a child) can. */ @@ -252,6 +260,9 @@ static void __call_usermodehelper(struct work_struct *work) enum umh_wait wait = sub_info->wait; pid_t pid; + if (wait != UMH_NO_WAIT) + wait &= ~UMH_KILLABLE; + /* CLONE_VFORK: wait until the usermode helper has execve'd * successfully We need the data structures to stay around * until that is done. */ @@ -461,9 +472,21 @@ int call_usermodehelper_exec(struct subprocess_info *sub_info, queue_work(khelper_wq, &sub_info->work); if (wait == UMH_NO_WAIT) /* task has freed sub_info */ goto unlock; - wait_for_completion(&done); - retval = sub_info->retval; + if (wait & UMH_KILLABLE) { + retval = wait_for_completion_killable(&done); + if (!retval) + goto wait_done; + + /* umh_complete() will see NULL and free sub_info */ + if (xchg(&sub_info->complete, NULL)) + goto unlock; + /* fallthrough, umh_complete() was already called */ + } + + wait_for_completion(&done); +wait_done: + retval = sub_info->retval; out: call_usermodehelper_freeinfo(sub_info); unlock: