[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>

4 files changed, 5 insertions, 6 deletions

diff --git a/drivers/net/8139too.c b/drivers/net/8139too.c
index 047202c4d9a..5a4a08a7c95 100644
--- a/drivers/net/8139too.c
+++ b/drivers/net/8139too.c
@@ -1606,7 +1606,7 @@ static int rtl8139_thread (void *data)
                 do {
                         timeout = interruptible_sleep_on_timeout (&tp->thr_wait, timeout);
                         /* make swsusp happy with our thread */
-                        try_to_freeze(PF_FREEZE);
+                        try_to_freeze();
                 } while (!signal_pending (current) && (timeout > 0));
 
                 if (signal_pending (current)) {
diff --git a/drivers/net/irda/sir_kthread.c b/drivers/net/irda/sir_kthread.c
index 18cea109953..c65054364bc 100644
--- a/drivers/net/irda/sir_kthread.c
+++ b/drivers/net/irda/sir_kthread.c
@@ -135,8 +135,7 @@ static int irda_thread(void *startup)
                 remove_wait_queue(&irda_rq_queue.kick, &wait);
 
                 /* make swsusp happy with our thread */
-                if (current->flags & PF_FREEZE)
-                        refrigerator(PF_FREEZE);
+                try_to_freeze();
 
                 run_irda_queue();
         }
diff --git a/drivers/net/irda/stir4200.c b/drivers/net/irda/stir4200.c
index 66f488c1371..15f207323d9 100644
--- a/drivers/net/irda/stir4200.c
+++ b/drivers/net/irda/stir4200.c
@@ -763,7 +763,7 @@ static int stir_transmit_thread(void *arg)
         {
 #ifdef CONFIG_PM
                 /* if suspending, then power off and wait */
-                if (unlikely(current->flags & PF_FREEZE)) {
+                if (unlikely(freezing(current))) {
                         if (stir->receiving)
                                 receive_stop(stir);
                         else
@@ -771,7 +771,7 @@ static int stir_transmit_thread(void *arg)
 
                         write_reg(stir, REG_CTRL1, CTRL1_TXPWD|CTRL1_RXPWD);
 
-                        refrigerator(PF_FREEZE);
+                        refrigerator();
 
                         if (change_speed(stir, stir->speed))
                                 break;
diff --git a/drivers/net/wireless/airo.c b/drivers/net/wireless/airo.c
index fb10a2db63a..d72e0385e4f 100644
--- a/drivers/net/wireless/airo.c
+++ b/drivers/net/wireless/airo.c
@@ -2918,7 +2918,7 @@ static int airo_thread(void *data) {
                         flush_signals(current);
 
                 /* make swsusp happy with our thread */
-                try_to_freeze(PF_FREEZE);
+                try_to_freeze();
 
                 if (test_bit(JOB_DIE, &ai->flags))
                         break;