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-rw-r--r--include/linux/kmod.h21
-rw-r--r--kernel/kmod.c47
-rw-r--r--kernel/power/process.c3
3 files changed, 58 insertions, 13 deletions
diff --git a/include/linux/kmod.h b/include/linux/kmod.h
index b087377..dd99c329 100644
--- a/include/linux/kmod.h
+++ b/include/linux/kmod.h
@@ -110,10 +110,27 @@ call_usermodehelper(char *path, char **argv, char **envp, int wait)
extern struct ctl_table usermodehelper_table[];
+enum umh_disable_depth {
+ UMH_ENABLED = 0,
+ UMH_FREEZING,
+ UMH_DISABLED,
+};
+
extern void usermodehelper_init(void);
-extern int usermodehelper_disable(void);
-extern void usermodehelper_enable(void);
+extern int __usermodehelper_disable(enum umh_disable_depth depth);
+extern void __usermodehelper_set_disable_depth(enum umh_disable_depth depth);
+
+static inline int usermodehelper_disable(void)
+{
+ return __usermodehelper_disable(UMH_DISABLED);
+}
+
+static inline void usermodehelper_enable(void)
+{
+ __usermodehelper_set_disable_depth(UMH_ENABLED);
+}
+
extern int usermodehelper_read_trylock(void);
extern long usermodehelper_read_lock_wait(long timeout);
extern void usermodehelper_read_unlock(void);
diff --git a/kernel/kmod.c b/kernel/kmod.c
index da7fcca..05698a7 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -322,7 +322,7 @@ static void __call_usermodehelper(struct work_struct *work)
* land has been frozen during a system-wide hibernation or suspend operation).
* Should always be manipulated under umhelper_sem acquired for write.
*/
-static int usermodehelper_disabled = 1;
+static enum umh_disable_depth usermodehelper_disabled = UMH_DISABLED;
/* Number of helpers running */
static atomic_t running_helpers = ATOMIC_INIT(0);
@@ -347,13 +347,30 @@ static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_disabled_waitq);
int usermodehelper_read_trylock(void)
{
+ DEFINE_WAIT(wait);
int ret = 0;
down_read(&umhelper_sem);
- if (usermodehelper_disabled) {
+ for (;;) {
+ prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
+ TASK_INTERRUPTIBLE);
+ if (!usermodehelper_disabled)
+ break;
+
+ if (usermodehelper_disabled == UMH_DISABLED)
+ ret = -EAGAIN;
+
up_read(&umhelper_sem);
- ret = -EAGAIN;
+
+ if (ret)
+ break;
+
+ schedule();
+ try_to_freeze();
+
+ down_read(&umhelper_sem);
}
+ finish_wait(&usermodehelper_disabled_waitq, &wait);
return ret;
}
EXPORT_SYMBOL_GPL(usermodehelper_read_trylock);
@@ -392,25 +409,35 @@ void usermodehelper_read_unlock(void)
EXPORT_SYMBOL_GPL(usermodehelper_read_unlock);
/**
- * usermodehelper_enable - allow new helpers to be started again
+ * __usermodehelper_set_disable_depth - Modify usermodehelper_disabled.
+ * depth: New value to assign to usermodehelper_disabled.
+ *
+ * Change the value of usermodehelper_disabled (under umhelper_sem locked for
+ * writing) and wakeup tasks waiting for it to change.
*/
-void usermodehelper_enable(void)
+void __usermodehelper_set_disable_depth(enum umh_disable_depth depth)
{
down_write(&umhelper_sem);
- usermodehelper_disabled = 0;
+ usermodehelper_disabled = depth;
wake_up(&usermodehelper_disabled_waitq);
up_write(&umhelper_sem);
}
/**
- * usermodehelper_disable - prevent new helpers from being started
+ * __usermodehelper_disable - Prevent new helpers from being started.
+ * @depth: New value to assign to usermodehelper_disabled.
+ *
+ * Set usermodehelper_disabled to @depth and wait for running helpers to exit.
*/
-int usermodehelper_disable(void)
+int __usermodehelper_disable(enum umh_disable_depth depth)
{
long retval;
+ if (!depth)
+ return -EINVAL;
+
down_write(&umhelper_sem);
- usermodehelper_disabled = 1;
+ usermodehelper_disabled = depth;
up_write(&umhelper_sem);
/*
@@ -425,7 +452,7 @@ int usermodehelper_disable(void)
if (retval)
return 0;
- usermodehelper_enable();
+ __usermodehelper_set_disable_depth(UMH_ENABLED);
return -EAGAIN;
}
diff --git a/kernel/power/process.c b/kernel/power/process.c
index 56eaac7..19db29f 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -123,7 +123,7 @@ int freeze_processes(void)
{
int error;
- error = usermodehelper_disable();
+ error = __usermodehelper_disable(UMH_FREEZING);
if (error)
return error;
@@ -135,6 +135,7 @@ int freeze_processes(void)
error = try_to_freeze_tasks(true);
if (!error) {
printk("done.");
+ __usermodehelper_set_disable_depth(UMH_DISABLED);
oom_killer_disable();
}
printk("\n");
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