X-Git-Url: http://pilppa.org/gitweb/gitweb.cgi?a=blobdiff_plain;f=kernel%2Fkmod.c;h=c6a4f8aebeba5c8a74a6bfc063e4ad08c3f14792;hb=71a27fecaf836093a30fe538c5ab98ef0b25bfc8;hp=78d365c524ed6ffac44da5c2d1e8fb672008b4a8;hpb=cdf4a6482dd4c739f8c1132c5a9356912911fec5;p=linux-2.6-omap-h63xx.git

diff --git a/kernel/kmod.c b/kernel/kmod.c
index 78d365c524e..c6a4f8aebeb 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -33,6 +33,8 @@
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/resource.h>
+#include <linux/notifier.h>
+#include <linux/suspend.h>
 #include <asm/uaccess.h>
 
 extern int max_threads;
@@ -265,13 +267,95 @@ static void __call_usermodehelper(struct work_struct *work)
 	}
 }
 
+#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.
  */
@@ -369,12 +453,13 @@ int call_usermodehelper_exec(struct subprocess_info *sub_info,
 	DECLARE_COMPLETION_ONSTACK(done);
 	int retval;
 
+	helper_lock();
 	if (sub_info->path[0] == '\0') {
 		retval = 0;
 		goto out;
 	}
 
-	if (!khelper_wq) {
+	if (!khelper_wq || usermodehelper_disabled) {
 		retval = -EBUSY;
 		goto out;
 	}
@@ -390,6 +475,7 @@ int call_usermodehelper_exec(struct subprocess_info *sub_info,
 
   out:
 	call_usermodehelper_freeinfo(sub_info);
+	helper_unlock();
 	return retval;
 }
 EXPORT_SYMBOL(call_usermodehelper_exec);
@@ -419,7 +505,7 @@ 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);
@@ -431,4 +517,5 @@ void __init usermodehelper_init(void)
 {
 	khelper_wq = create_singlethread_workqueue("khelper");
 	BUG_ON(!khelper_wq);
+	register_pm_notifier_callback();
 }