[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>

7 files changed, 7 insertions, 16 deletions

diff --git a/arch/frv/kernel/signal.c b/arch/frv/kernel/signal.c
index d8d8f3d..36a2dff 100644
--- a/arch/frv/kernel/signal.c
+++ b/arch/frv/kernel/signal.c
@@ -536,10 +536,8 @@ int do_signal(struct pt_regs *regs, sigset_t *oldset)
 	if (!user_mode(regs))
 		return 1;
 
-	if (current->flags & PF_FREEZE) {
-		refrigerator(0);
+	if (try_to_freeze())
 		goto no_signal;
-	}
 
 	if (!oldset)
 		oldset = &current->blocked;
diff --git a/arch/h8300/kernel/signal.c b/arch/h8300/kernel/signal.c
index a4799d6..5aab87e 100644
--- a/arch/h8300/kernel/signal.c
+++ b/arch/h8300/kernel/signal.c
@@ -517,10 +517,8 @@ asmlinkage int do_signal(struct pt_regs *regs, sigset_t *oldset)
 	if ((regs->ccr & 0x10))
 		return 1;
 
-	if (current->flags & PF_FREEZE) {
-		refrigerator(0);
+	if (try_to_freeze())
 		goto no_signal;
-	}
 
 	current->thread.esp0 = (unsigned long) regs;
 
diff --git a/arch/i386/kernel/io_apic.c b/arch/i386/kernel/io_apic.c
index 08540bc..2451a3a 100644
--- a/arch/i386/kernel/io_apic.c
+++ b/arch/i386/kernel/io_apic.c
@@ -573,7 +573,7 @@ static int balanced_irq(void *unused)
 	for ( ; ; ) {
 		set_current_state(TASK_INTERRUPTIBLE);
 		time_remaining = schedule_timeout(time_remaining);
-		try_to_freeze(PF_FREEZE);
+		try_to_freeze();
 		if (time_after(jiffies,
 				prev_balance_time+balanced_irq_interval)) {
 			do_irq_balance();
diff --git a/arch/i386/kernel/signal.c b/arch/i386/kernel/signal.c
index b9b8f4e..ac5b1e9 100644
--- a/arch/i386/kernel/signal.c
+++ b/arch/i386/kernel/signal.c
@@ -608,10 +608,8 @@ int fastcall do_signal(struct pt_regs *regs, sigset_t *oldset)
 	if (!user_mode(regs))
 		return 1;
 
-	if (current->flags & PF_FREEZE) {
-		refrigerator(0);
+	if (try_to_freeze)
 		goto no_signal;
-	}
 
 	if (!oldset)
 		oldset = &current->blocked;
diff --git a/arch/m32r/kernel/signal.c b/arch/m32r/kernel/signal.c
index 50311eb..5aef7e4 100644
--- a/arch/m32r/kernel/signal.c
+++ b/arch/m32r/kernel/signal.c
@@ -371,10 +371,8 @@ int do_signal(struct pt_regs *regs, sigset_t *oldset)
 	if (!user_mode(regs))
 		return 1;
 
-	if (current->flags & PF_FREEZE) {
-		refrigerator(0);
+	if (try_to_freeze()) 
 		goto no_signal;
-	}
 
 	if (!oldset)
 		oldset = &current->blocked;
diff --git a/arch/ppc/kernel/signal.c b/arch/ppc/kernel/signal.c
index 7c8437da..8aaeb6f 100644
--- a/arch/ppc/kernel/signal.c
+++ b/arch/ppc/kernel/signal.c
@@ -705,8 +705,7 @@ int do_signal(sigset_t *oldset, struct pt_regs *regs)
 	unsigned long frame, newsp;
 	int signr, ret;
 
-	if (current->flags & PF_FREEZE) {
-		refrigerator(PF_FREEZE);
+	if (try_to_freeze()) {
 		signr = 0;
 		if (!signal_pending(current))
 			goto no_signal;
diff --git a/arch/x86_64/kernel/signal.c b/arch/x86_64/kernel/signal.c
index 98b7ba9..98590a9 100644
--- a/arch/x86_64/kernel/signal.c
+++ b/arch/x86_64/kernel/signal.c
@@ -425,7 +425,7 @@ int do_signal(struct pt_regs *regs, sigset_t *oldset)
 	if (!user_mode(regs))
 		return 1;
 
-	if (try_to_freeze(0))
+	if (try_to_freeze())
 		goto no_signal;
 
 	if (!oldset)