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authorRafael J. Wysocki <rjw@sisk.pl>2008-10-15 22:01:21 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-10-16 11:21:29 -0700
commit1bfcf1304ea79c46efc3724e548b13b4b442b418 (patch)
tree5adbf95b25d1d9e86fc0e5d0784550ccb9bf5be9
parent574f34cee2b6574d43bf4506f771c1cec6a5d391 (diff)
downloadop-kernel-dev-1bfcf1304ea79c46efc3724e548b13b4b442b418.zip
op-kernel-dev-1bfcf1304ea79c46efc3724e548b13b4b442b418.tar.gz
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>
-rw-r--r--include/linux/kmod.h3
-rw-r--r--kernel/kmod.c65
-rw-r--r--kernel/power/disk.c11
-rw-r--r--kernel/power/main.c7
-rw-r--r--kernel/power/user.c10
5 files changed, 58 insertions, 38 deletions
diff --git a/include/linux/kmod.h b/include/linux/kmod.h
index a1a9157..92213a9 100644
--- 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 2456d1a..ab7dd08 100644
--- 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 bbd85c6..331f983 100644
--- 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 540b16b..19122cf 100644
--- 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 a6332a3..005b93d 100644
--- 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;
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