Freezer: Fix APM emulation breakage

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>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 8 insertions, 7 deletions

diff --git a/drivers/char/apm-emulation.c b/drivers/char/apm-emulation.c
index c99e43b837f5..17d54315e146 100644
--- 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 file *filp, u_int cmd, u_long arg)
                          * 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 file *filp, u_int cmd, u_long arg)
                          * 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;