[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/fs/afs/kafsasyncd.c b/fs/afs/kafsasyncd.c
index 6fc88ae..7ac07d0 100644
--- a/fs/afs/kafsasyncd.c
+++ b/fs/afs/kafsasyncd.c
@@ -116,7 +116,7 @@
remove_wait_queue(&kafsasyncd_sleepq, &myself);
set_current_state(TASK_RUNNING);
- try_to_freeze(PF_FREEZE);
+ try_to_freeze();
/* discard pending signals */
afs_discard_my_signals();
diff --git a/fs/afs/kafstimod.c b/fs/afs/kafstimod.c
index 86e710d..65bc05a 100644
--- a/fs/afs/kafstimod.c
+++ b/fs/afs/kafstimod.c
@@ -91,7 +91,7 @@
complete_and_exit(&kafstimod_dead, 0);
}
- try_to_freeze(PF_FREEZE);
+ try_to_freeze();
/* discard pending signals */
afs_discard_my_signals();
diff --git a/fs/jbd/journal.c b/fs/jbd/journal.c
index 1e6f2e2..5e7b439 100644
--- a/fs/jbd/journal.c
+++ b/fs/jbd/journal.c
@@ -167,7 +167,7 @@
}
wake_up(&journal->j_wait_done_commit);
- if (current->flags & PF_FREEZE) {
+ if (freezing(current)) {
/*
* The simpler the better. Flushing journal isn't a
* good idea, because that depends on threads that may
@@ -175,7 +175,7 @@
*/
jbd_debug(1, "Now suspending kjournald\n");
spin_unlock(&journal->j_state_lock);
- refrigerator(PF_FREEZE);
+ refrigerator();
spin_lock(&journal->j_state_lock);
} else {
/*
diff --git a/fs/jfs/jfs_logmgr.c b/fs/jfs/jfs_logmgr.c
index 7c8387e..79d0762 100644
--- a/fs/jfs/jfs_logmgr.c
+++ b/fs/jfs/jfs_logmgr.c
@@ -2359,9 +2359,9 @@
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);
diff --git a/fs/jfs/jfs_txnmgr.c b/fs/jfs/jfs_txnmgr.c
index 8cbaaff..121c981 100644
--- a/fs/jfs/jfs_txnmgr.c
+++ b/fs/jfs/jfs_txnmgr.c
@@ -2788,9 +2788,9 @@
/* 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 @@
/* 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);
diff --git a/fs/lockd/clntproc.c b/fs/lockd/clntproc.c
index fd77ed1..14b3ce8 100644
--- a/fs/lockd/clntproc.c
+++ b/fs/lockd/clntproc.c
@@ -313,7 +313,7 @@
prepare_to_wait(queue, &wait, TASK_INTERRUPTIBLE);
if (!signalled ()) {
schedule_timeout(NLMCLNT_GRACE_WAIT);
- try_to_freeze(PF_FREEZE);
+ try_to_freeze();
if (!signalled ())
status = 0;
}
diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c
index c60e694..df0cba2 100644
--- a/fs/xfs/linux-2.6/xfs_buf.c
+++ b/fs/xfs/linux-2.6/xfs_buf.c
@@ -1771,9 +1771,9 @@
INIT_LIST_HEAD(&tmp);
do {
- if (unlikely(current->flags & PF_FREEZE)) {
+ if (unlikely(freezing(current))) {
xfsbufd_force_sleep = 1;
- refrigerator(PF_FREEZE);
+ refrigerator();
} else {
xfsbufd_force_sleep = 0;
}
diff --git a/fs/xfs/linux-2.6/xfs_super.c b/fs/xfs/linux-2.6/xfs_super.c
index 5fe9af3..f6dd7de 100644
--- a/fs/xfs/linux-2.6/xfs_super.c
+++ b/fs/xfs/linux-2.6/xfs_super.c
@@ -483,7 +483,7 @@
set_current_state(TASK_INTERRUPTIBLE);
timeleft = schedule_timeout(timeleft);
/* swsusp */
- try_to_freeze(PF_FREEZE);
+ try_to_freeze();
if (vfsp->vfs_flag & VFS_UMOUNT)
break;