X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=kernel%2Fkmod.c;h=bb7df2a28bd719d07978593cb10f7264b6f43f3b;hb=3ba5619f06300cd0944150901ed20de87483ad8c;hp=d2dce71115d8cddf28dbe089b2b7bb29b59034c1;hpb=0ab4dc92278a0f3816e486d6350c6652a72e06c8;p=linux-2.6 diff --git a/kernel/kmod.c b/kernel/kmod.c index d2dce71115..bb7df2a28b 100644 --- a/kernel/kmod.c +++ b/kernel/kmod.c @@ -33,6 +33,8 @@ #include #include #include +#include +#include #include extern int max_threads; @@ -119,7 +121,7 @@ struct subprocess_info { char **argv; char **envp; struct key *ring; - int wait; + enum umh_wait wait; int retval; struct file *stdin; void (*cleanup)(char **argv, char **envp); @@ -225,7 +227,7 @@ static int wait_for_helper(void *data) sub_info->retval = ret; } - if (sub_info->wait < 0) + if (sub_info->wait == UMH_NO_WAIT) call_usermodehelper_freeinfo(sub_info); else complete(sub_info->complete); @@ -238,35 +240,122 @@ static void __call_usermodehelper(struct work_struct *work) struct subprocess_info *sub_info = container_of(work, struct subprocess_info, work); pid_t pid; - int wait = sub_info->wait; + enum umh_wait wait = sub_info->wait; /* CLONE_VFORK: wait until the usermode helper has execve'd * successfully We need the data structures to stay around * until that is done. */ - if (wait) + if (wait == UMH_WAIT_PROC || wait == UMH_NO_WAIT) pid = kernel_thread(wait_for_helper, sub_info, CLONE_FS | CLONE_FILES | SIGCHLD); else pid = kernel_thread(____call_usermodehelper, sub_info, CLONE_VFORK | SIGCHLD); - if (wait < 0) - return; + switch (wait) { + case UMH_NO_WAIT: + break; - if (pid < 0) { + case UMH_WAIT_PROC: + if (pid > 0) + break; sub_info->retval = pid; + /* FALLTHROUGH */ + + case UMH_WAIT_EXEC: complete(sub_info->complete); - } else if (!wait) - complete(sub_info->complete); + } +} + +#ifdef CONFIG_PM +/* + * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY + * (used for preventing user land processes from being created after the user + * land has been frozen during a system-wide hibernation or suspend operation). + */ +static int usermodehelper_disabled; + +/* Number of helpers running */ +static atomic_t running_helpers = ATOMIC_INIT(0); + +/* + * Wait queue head used by usermodehelper_pm_callback() to wait for all running + * helpers to finish. + */ +static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq); + +/* + * Time to wait for running_helpers to become zero before the setting of + * usermodehelper_disabled in usermodehelper_pm_callback() fails + */ +#define RUNNING_HELPERS_TIMEOUT (5 * HZ) + +static int usermodehelper_pm_callback(struct notifier_block *nfb, + unsigned long action, + void *ignored) +{ + long retval; + + switch (action) { + case PM_HIBERNATION_PREPARE: + case PM_SUSPEND_PREPARE: + usermodehelper_disabled = 1; + smp_mb(); + /* + * From now on call_usermodehelper_exec() won't start any new + * helpers, so it is sufficient if running_helpers turns out to + * be zero at one point (it may be increased later, but that + * doesn't matter). + */ + retval = wait_event_timeout(running_helpers_waitq, + atomic_read(&running_helpers) == 0, + RUNNING_HELPERS_TIMEOUT); + if (retval) { + return NOTIFY_OK; + } else { + usermodehelper_disabled = 0; + return NOTIFY_BAD; + } + case PM_POST_HIBERNATION: + case PM_POST_SUSPEND: + usermodehelper_disabled = 0; + return NOTIFY_OK; + } + + return NOTIFY_DONE; +} + +static void helper_lock(void) +{ + atomic_inc(&running_helpers); + smp_mb__after_atomic_inc(); } +static void helper_unlock(void) +{ + if (atomic_dec_and_test(&running_helpers)) + wake_up(&running_helpers_waitq); +} + +static void register_pm_notifier_callback(void) +{ + pm_notifier(usermodehelper_pm_callback, 0); +} +#else /* CONFIG_PM */ +#define usermodehelper_disabled 0 + +static inline void helper_lock(void) {} +static inline void helper_unlock(void) {} +static inline void register_pm_notifier_callback(void) {} +#endif /* CONFIG_PM */ + /** * call_usermodehelper_setup - prepare to call a usermode helper - * @path - path to usermode executable - * @argv - arg vector for process - * @envp - environment for process + * @path: path to usermode executable + * @argv: arg vector for process + * @envp: environment for process * - * 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 * exec the process and free the structure. */ @@ -359,17 +448,16 @@ EXPORT_SYMBOL(call_usermodehelper_stdinpipe); * (ie. it runs with full root capabilities). */ int call_usermodehelper_exec(struct subprocess_info *sub_info, - int wait) + enum umh_wait wait) { DECLARE_COMPLETION_ONSTACK(done); - int retval; + int retval = 0; - if (sub_info->path[0] == '\0') { - retval = 0; + helper_lock(); + if (sub_info->path[0] == '\0') goto out; - } - if (!khelper_wq) { + if (!khelper_wq || usermodehelper_disabled) { retval = -EBUSY; goto out; } @@ -378,13 +466,15 @@ int call_usermodehelper_exec(struct subprocess_info *sub_info, sub_info->wait = wait; queue_work(khelper_wq, &sub_info->work); - if (wait < 0) /* task has freed sub_info */ - return 0; + if (wait == UMH_NO_WAIT) /* task has freed sub_info */ + goto unlock; wait_for_completion(&done); retval = sub_info->retval; - out: +out: call_usermodehelper_freeinfo(sub_info); +unlock: + helper_unlock(); return retval; } EXPORT_SYMBOL(call_usermodehelper_exec); @@ -414,7 +504,7 @@ int call_usermodehelper_pipe(char *path, char **argv, char **envp, if (ret < 0) goto out; - return call_usermodehelper_exec(sub_info, 1); + return call_usermodehelper_exec(sub_info, UMH_WAIT_EXEC); out: call_usermodehelper_freeinfo(sub_info); @@ -426,4 +516,5 @@ void __init usermodehelper_init(void) { khelper_wq = create_singlethread_workqueue("khelper"); BUG_ON(!khelper_wq); + register_pm_notifier_callback(); }