[ALSA] opl3sa2 - Add Neomagic MagicWave 3D ISA PnP ID

[pandora-kernel.git] / kernel / kmod.c

diff --git a/kernel/kmod.c b/kernel/kmod.c
index 78d365c..beedbdc 100644 (file)
--- 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;
@@ -265,6 +267,88 @@ 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
@@ -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);
@@ -431,4 +517,5 @@ void __init usermodehelper_init(void)
 {
        khelper_wq = create_singlethread_workqueue("khelper");
        BUG_ON(!khelper_wq);
+       register_pm_notifier_callback();
 }