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Subject[patch 41/73] Freezer: Fix APM emulation breakage
2.6.23-stable review patch.  If anyone has any objections, please let us know.
------------------
From: Rafael J. Wysocki <rjw@sisk.pl>
The APM emulation is currently broken as a result of commit
831441862956fffa17b9801db37e6ea1650b0f69
"Freezer: make kernel threads nonfreezable by default"
that removed the PF_NOFREEZE annotations from apm_ioctl() without
adding the appropriate freezer hooks. Fix it and remove the
unnecessary variable flags from apm_ioctl().

This problem has been fixed in the mainline by
commit cb43c54ca05c01533c45e4d3abfe8f99b7acf624
"Freezer: Fix APM emulation breakage".

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/char/apm-emulation.c | 15 ++++++++-------
include/linux/freezer.h | 23 +++++++++++++++++++++++
2 files changed, 31 insertions(+), 7 deletions(-)
--- a/drivers/char/apm-emulation.c
+++ b/drivers/char/apm-emulation.c
@@ -295,7 +295,6 @@ static int
apm_ioctl(struct inode * inode, struct file *filp, u_int cmd, u_long arg)
{
struct apm_user *as = filp->private_data;
- unsigned long flags;
int err = -EINVAL;

if (!as->suser || !as->writer)
@@ -331,10 +330,16 @@ apm_ioctl(struct inode * inode, struct f
* Wait for the suspend/resume to complete. If there
* are pending acknowledges, we wait here for them.
*/
- flags = current->flags;
+ freezer_do_not_count();

wait_event(apm_suspend_waitqueue,
as->suspend_state == SUSPEND_DONE);
+
+ /*
+ * Since we are waiting until the suspend is done, the
+ * try_to_freeze() in freezer_count() will not trigger
+ */
+ freezer_count();
} else {
as->suspend_state = SUSPEND_WAIT;
mutex_unlock(&state_lock);
@@ -362,14 +367,10 @@ apm_ioctl(struct inode * inode, struct f
* Wait for the suspend/resume to complete. If there
* are pending acknowledges, we wait here for them.
*/
- flags = current->flags;
-
- wait_event_interruptible(apm_suspend_waitqueue,
+ wait_event_freezable(apm_suspend_waitqueue,
as->suspend_state == SUSPEND_DONE);
}

- current->flags = flags;
-
mutex_lock(&state_lock);
err = as->suspend_result;
as->suspend_state = SUSPEND_NONE;
--- a/include/linux/freezer.h
+++ b/include/linux/freezer.h
@@ -4,6 +4,7 @@
#define FREEZER_H_INCLUDED

#include <linux/sched.h>
+#include <linux/wait.h>

#ifdef CONFIG_PM_SLEEP
/*
@@ -126,6 +127,24 @@ static inline void set_freezable(void)
current->flags &= ~PF_NOFREEZE;
}

+/*
+ * Freezer-friendly wrapper around wait_event_interruptible(), originally
+ * defined in <linux/wait.h>
+ */
+
+#define wait_event_freezable(wq, condition) \
+({ \
+ int __retval; \
+ do { \
+ __retval = wait_event_interruptible(wq, \
+ (condition) || freezing(current)); \
+ if (__retval && !freezing(current)) \
+ break; \
+ else if (!(condition)) \
+ __retval = -ERESTARTSYS; \
+ } while (try_to_freeze()); \
+ __retval; \
+})
#else /* !CONFIG_PM_SLEEP */
static inline int frozen(struct task_struct *p) { return 0; }
static inline int freezing(struct task_struct *p) { return 0; }
@@ -143,6 +162,10 @@ static inline void freezer_do_not_count(
static inline void freezer_count(void) {}
static inline int freezer_should_skip(struct task_struct *p) { return 0; }
static inline void set_freezable(void) {}
+
+#define wait_event_freezable(wq, condition) \
+ wait_event_interruptible(wq, condition)
+
#endif /* !CONFIG_PM_SLEEP */

#endif /* FREEZER_H_INCLUDED */
--


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