[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>

8 files changed, 14 insertions, 14 deletions

diff --git a/fs/afs/kafsasyncd.c b/fs/afs/kafsasyncd.c
index 6fc88ae8ad94..7ac07d0d47b9 100644
--- a/fs/afs/kafsasyncd.c
+++ b/fs/afs/kafsasyncd.c
@@ -116,7 +116,7 @@ static int kafsasyncd(void *arg)
                 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 86e710dd057e..65bc05ab8182 100644
--- a/fs/afs/kafstimod.c
+++ b/fs/afs/kafstimod.c
@@ -91,7 +91,7 @@ static int kafstimod(void *arg)
                         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 1e6f2e2ad4a3..5e7b43949517 100644
--- a/fs/jbd/journal.c
+++ b/fs/jbd/journal.c
@@ -167,7 +167,7 @@ loop:
         }
 
         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 @@ loop:
                  */
                 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 7c8387ed4192..79d07624bfe1 100644
--- a/fs/jfs/jfs_logmgr.c
+++ b/fs/jfs/jfs_logmgr.c
@@ -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);
diff --git a/fs/jfs/jfs_txnmgr.c b/fs/jfs/jfs_txnmgr.c
index 8cbaaff1d5fa..121c981ff453 100644
--- a/fs/jfs/jfs_txnmgr.c
+++ b/fs/jfs/jfs_txnmgr.c
@@ -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);
 
diff --git a/fs/lockd/clntproc.c b/fs/lockd/clntproc.c
index fd77ed1d710d..14b3ce87fa29 100644
--- a/fs/lockd/clntproc.c
+++ b/fs/lockd/clntproc.c
@@ -313,7 +313,7 @@ static int nlm_wait_on_grace(wait_queue_head_t *queue)
         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 c60e69431e11..df0cba239dd5 100644
--- a/fs/xfs/linux-2.6/xfs_buf.c
+++ b/fs/xfs/linux-2.6/xfs_buf.c
@@ -1771,9 +1771,9 @@ xfsbufd(
 
         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 5fe9af38aa20..f6dd7de25927 100644
--- a/fs/xfs/linux-2.6/xfs_super.c
+++ b/fs/xfs/linux-2.6/xfs_super.c
@@ -483,7 +483,7 @@ xfssyncd(
                 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;