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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
fs/jfs/jfs_logmgr.c
View File

@@ -2359,9 +2359,9 @@ int jfsIOWait(void *arg)
lbmStartIO(bp);
spin_lock_irq(&log_redrive_lock);
}
if (current->flags & PF_FREEZE) {
if (freezing(current)) {
spin_unlock_irq(&log_redrive_lock);
refrigerator(PF_FREEZE);
refrigerator();
} else {
add_wait_queue(&jfs_IO_thread_wait, &wq);
set_current_state(TASK_INTERRUPTIBLE);

8
fs/jfs/jfs_txnmgr.c
View File

@@ -2788,9 +2788,9 @@ int jfs_lazycommit(void *arg)
/* In case a wakeup came while all threads were active */
jfs_commit_thread_waking = 0;
if (current->flags & PF_FREEZE) {
if (freezing(current)) {
LAZY_UNLOCK(flags);
refrigerator(PF_FREEZE);
refrigerator();
} else {
DECLARE_WAITQUEUE(wq, current);
@@ -2987,9 +2987,9 @@ int jfs_sync(void *arg)
/* Add anon_list2 back to anon_list */
list_splice_init(&TxAnchor.anon_list2, &TxAnchor.anon_list);
if (current->flags & PF_FREEZE) {
if (freezing(current)) {
TXN_UNLOCK();
refrigerator(PF_FREEZE);
refrigerator();
} else {
DECLARE_WAITQUEUE(wq, current);