[PATCH] Cleanup patch for process freezing
1. Establish a simple API for process freezing defined in linux/include/sched.h:
frozen(process) Check for frozen process
freezing(process) Check if a process is being frozen
freeze(process) Tell a process to freeze (go to refrigerator)
thaw_process(process) Restart process
frozen_process(process) Process is frozen now
2. Remove all references to PF_FREEZE and PF_FROZEN from all
kernel sources except sched.h
3. Fix numerous locations where try_to_freeze is manually done by a driver
4. Remove the argument that is no longer necessary from two function calls.
5. Some whitespace cleanup
6. Clear potential race in refrigerator (provides an open window of PF_FREEZE
cleared before setting PF_FROZEN, recalc_sigpending does not check
PF_FROZEN).
This patch does not address the problem of freeze_processes() violating the rule
that a task may only modify its own flags by setting PF_FREEZE. This is not clean
in an SMP environment. freeze(process) is therefore not SMP safe!
Signed-off-by: Christoph Lameter <christoph@lameter.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index d2d648e..a8d879a 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -2808,7 +2808,7 @@
do {
hub_events();
wait_event_interruptible(khubd_wait, !list_empty(&hub_event_list));
- try_to_freeze(PF_FREEZE);
+ try_to_freeze();
} while (!signal_pending(current));
pr_debug ("%s: khubd exiting\n", usbcore_name);
diff --git a/drivers/usb/gadget/file_storage.c b/drivers/usb/gadget/file_storage.c
index 037a7f1..a9be851 100644
--- a/drivers/usb/gadget/file_storage.c
+++ b/drivers/usb/gadget/file_storage.c
@@ -1554,8 +1554,7 @@
rc = wait_event_interruptible(fsg->thread_wqh,
fsg->thread_wakeup_needed);
fsg->thread_wakeup_needed = 0;
- if (current->flags & PF_FREEZE)
- refrigerator(PF_FREEZE);
+ try_to_freeze();
return (rc ? -EINTR : 0);
}
diff --git a/drivers/usb/storage/usb.c b/drivers/usb/storage/usb.c
index 35c1ca6..77e7fc2 100644
--- a/drivers/usb/storage/usb.c
+++ b/drivers/usb/storage/usb.c
@@ -847,10 +847,8 @@
wait_event_interruptible_timeout(us->delay_wait,
test_bit(US_FLIDX_DISCONNECTING, &us->flags),
delay_use * HZ);
- if (current->flags & PF_FREEZE) {
- refrigerator(PF_FREEZE);
+ if (try_to_freeze())
goto retry;
- }
}
/* If the device is still connected, perform the scanning */