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[PATCH] Cleanup patch for process freezing

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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>
This commit is contained in:
Christoph Lameter
2005-06-24 23:13:50 -07:00
committed by Linus Torvalds
parent b3e112bcc1
commit 3e1d1d28d9
47 changed files with 126 additions and 113 deletions
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4
drivers/usb/storage/usb.c
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@@ -847,10 +847,8 @@ retry:
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 */