[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 d8d8f3d4304d..36a2dffc8ebd 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 a4799d633ef4..5aab87eae1f9 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 08540bc4ba3e..2451a3a99440 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 b9b8f4e20fad..ac5b1e975c5c 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 50311eb07a24..5aef7e406ef5 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 7c8437da09d5..8aaeb6f4e750 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 98b7ba95d581..98590a989f3d 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)