[PATCH 2/2] Freezer: Fix APM emulation breakage

Rafael J. Wysocki
2007-11-21T22:26:33Z

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().

Special thanks to Franck Bui-Huu <vagabon.xyz@gmail.com> for pointing out the
problem.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Franck Bui-Huu <vagabon.xyz@gmail.com>
Cc: Nigel Cunningham <nigel@nigel.suspend2.net>
---
drivers/char/apm-emulation.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)

Index: linux-2.6/drivers/char/apm-emulation.c
===================================================================
--- linux-2.6.orig/drivers/char/apm-emulation.c
+++ linux-2.6/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;