pm: rework disabling of user mode helpers during suspend/hibernation

We currently use a PM notifier to disable user mode helpers before suspend
and hibernation and to re-enable them during resume.  However, this is not
an ideal solution, because if any drivers want to upload firmware into
memory before suspend, they have to use a PM notifier for this purpose and
there is no guarantee that the ordering of PM notifiers will be as
expected (ie.  the notifier that disables user mode helpers has to be run
after the driver's notifier used for uploading the firmware).

For this reason, it seems better to move the disabling and enabling of
user mode helpers to separate functions that will be called by the PM core
as necessary.

[akpm@linux-foundation.org: remove unneeded ifdefs]
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/kmod.h b/include/linux/kmod.h
index a1a91577813c6bfb25ea89c9304f0c2128a87464..92213a9194e15753b91a21170cb641e97d82513d 100644 (file)
--- a/include/linux/kmod.h
+++ b/include/linux/kmod.h
@@ -99,4 +99,7 @@ struct file;
 extern int call_usermodehelper_pipe(char *path, char *argv[], char *envp[],
                                    struct file **filp);
 
+extern int usermodehelper_disable(void);
+extern void usermodehelper_enable(void);
+
 #endif /* __LINUX_KMOD_H__ */

diff --git a/kernel/kmod.c b/kernel/kmod.c
index 2456d1a0befbd45b91cd7cb7a97ae6d2fb270c4c..ab7dd08472fce4c56311f29d7d3920a4e3bbd500 100644 (file)
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -265,7 +265,7 @@ static void __call_usermodehelper(struct work_struct *work)
        }
 }
 
-#ifdef CONFIG_PM
+#ifdef CONFIG_PM_SLEEP
 /*
  * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY
  * (used for preventing user land processes from being created after the user
@@ -288,39 +288,37 @@ static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq);
  */
 #define RUNNING_HELPERS_TIMEOUT        (5 * HZ)
 
-static int usermodehelper_pm_callback(struct notifier_block *nfb,
-                                       unsigned long action,
-                                       void *ignored)
+/**
+ * usermodehelper_disable - prevent new helpers from being started
+ */
+int usermodehelper_disable(void)
 {
        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,
+       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;
-       }
+       if (retval)
+               return 0;
 
-       return NOTIFY_DONE;
+       usermodehelper_disabled = 0;
+       return -EAGAIN;
+}
+
+/**
+ * usermodehelper_enable - allow new helpers to be started again
+ */
+void usermodehelper_enable(void)
+{
+       usermodehelper_disabled = 0;
 }
 
 static void helper_lock(void)
@@ -334,18 +332,12 @@ 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 */
+#else /* CONFIG_PM_SLEEP */
 #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 */
+#endif /* CONFIG_PM_SLEEP */
 
 /**
  * call_usermodehelper_setup - prepare to call a usermode helper
@@ -515,5 +507,4 @@ void __init usermodehelper_init(void)
 {
        khelper_wq = create_singlethread_workqueue("khelper");
        BUG_ON(!khelper_wq);
-       register_pm_notifier_callback();
 }

diff --git a/kernel/power/disk.c b/kernel/power/disk.c
index bbd85c60f7419f5fca1cbf1d0b5d6e6aad37f625..331f9836383feaba687c89c3e4596edff76fb2fe 100644 (file)
--- a/kernel/power/disk.c
+++ b/kernel/power/disk.c
@@ -14,6 +14,7 @@
 #include <linux/reboot.h>
 #include <linux/string.h>
 #include <linux/device.h>
+#include <linux/kmod.h>
 #include <linux/delay.h>
 #include <linux/fs.h>
 #include <linux/mount.h>
@@ -520,6 +521,10 @@ int hibernate(void)
        if (error)
                goto Exit;
 
+       error = usermodehelper_disable();
+       if (error)
+               goto Exit;
+
        /* Allocate memory management structures */
        error = create_basic_memory_bitmaps();
        if (error)
@@ -558,6 +563,7 @@ int hibernate(void)
        thaw_processes();
  Finish:
        free_basic_memory_bitmaps();
+       usermodehelper_enable();
  Exit:
        pm_notifier_call_chain(PM_POST_HIBERNATION);
        pm_restore_console();
@@ -634,6 +640,10 @@ static int software_resume(void)
        if (error)
                goto Finish;
 
+       error = usermodehelper_disable();
+       if (error)
+               goto Finish;
+
        error = create_basic_memory_bitmaps();
        if (error)
                goto Finish;
@@ -656,6 +666,7 @@ static int software_resume(void)
        thaw_processes();
  Done:
        free_basic_memory_bitmaps();
+       usermodehelper_enable();
  Finish:
        pm_notifier_call_chain(PM_POST_RESTORE);
        pm_restore_console();

diff --git a/kernel/power/main.c b/kernel/power/main.c
index 540b16b68565e74fb9f51f68134f68cc3011b0a0..19122cf6d827d13d03e8a7520d0120d5adf92bbc 100644 (file)
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -14,6 +14,7 @@
 #include <linux/string.h>
 #include <linux/delay.h>
 #include <linux/errno.h>
+#include <linux/kmod.h>
 #include <linux/init.h>
 #include <linux/console.h>
 #include <linux/cpu.h>
@@ -237,6 +238,10 @@ static int suspend_prepare(void)
        if (error)
                goto Finish;
 
+       error = usermodehelper_disable();
+       if (error)
+               goto Finish;
+
        if (suspend_freeze_processes()) {
                error = -EAGAIN;
                goto Thaw;
@@ -256,6 +261,7 @@ static int suspend_prepare(void)
 
  Thaw:
        suspend_thaw_processes();
+       usermodehelper_enable();
  Finish:
        pm_notifier_call_chain(PM_POST_SUSPEND);
        pm_restore_console();
@@ -376,6 +382,7 @@ int suspend_devices_and_enter(suspend_state_t state)
 static void suspend_finish(void)
 {
        suspend_thaw_processes();
+       usermodehelper_enable();
        pm_notifier_call_chain(PM_POST_SUSPEND);
        pm_restore_console();
 }

diff --git a/kernel/power/user.c b/kernel/power/user.c
index a6332a3132620b4563e3be8a0fbfb9639b1e5405..005b93d839ba1268da0c80c3106739ee388d996a 100644 (file)
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -212,13 +212,20 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd,
        case SNAPSHOT_FREEZE:
                if (data->frozen)
                        break;
+
                printk("Syncing filesystems ... ");
                sys_sync();
                printk("done.\n");
 
-               error = freeze_processes();
+               error = usermodehelper_disable();
                if (error)
+                       break;
+
+               error = freeze_processes();
+               if (error) {
                        thaw_processes();
+                       usermodehelper_enable();
+               }
                if (!error)
                        data->frozen = 1;
                break;
@@ -227,6 +234,7 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd,
                if (!data->frozen || data->ready)
                        break;
                thaw_processes();
+               usermodehelper_enable();
                data->frozen = 0;
                break;