redonkable
/
alistair23-linux
1
0
Fork 0
Code Releases Activity

apm-emulation: use wait_event_freezable() instead of freezer_[do_not_]count() 

vfork is moving away from freezer_[do_not_]count() one way or the
other leaving apm_ioctl() as the only user.  apm_ioctl() just wants to
wait for suspend/resume cycle to complete without hindering the
freezer.  Use wait_event_freezable() instead.

The only annoyance is that wait_event_freezable() wakes up with
-ERESTART if there are pending signals while apm_ioctl() wants to
ignore all signals until suspend is complete.  We can play with
@current->[real_]blocked but this is hardly a performance or latency
critical path - simply chill a bit on each iteration until
SUSPEND_DONE for unlikely cases where there are pending signals.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
hifive-unleashed-5.1
Tejun Heo 2011-08-18 10:06:53 +02:00 committed by Jiri Kosina
parent 51414d4108
commit 1d927c3b5a
1 changed files with 6 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
drivers/char/apm-emulation.c
View File

@ -300,17 +300,13 @@ apm_ioctl(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.
* wait_event_freezable() is interruptible and pending
* signal can cause busy looping. We aren't doing
* anything critical, chill a bit on each iteration.
*/
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();
while (wait_event_freezable(apm_suspend_waitqueue,
as->suspend_state == SUSPEND_DONE))
msleep(10);
break;
case SUSPEND_ACKTO:
as->suspend_result = -ETIMEDOUT;