[PATCH] irqlock patch 2.5.27-H6

 - init thread needs to have preempt_count of 1 until sched_init().
   (William Lee Irwin III)
 - clean up the irq-mask macros. (Linus)
 - add barrier() to irq_enter() and irq_exit(). (based on Oleg Nesterov's
   comment.)
 - move the irqs-off check into preempt_schedule() and remove
   CONFIG_DEBUG_IRQ_SCHEDULE.
 - remove spin_unlock_no_resched() and comment the affected places more
   agressively.
 - slab.c needs to spin_unlock_no_resched(), instead of spin_unlock(). (It
   also has to check for preemption in the right spot.) This should fix
   the memory corruption.
 - irq_exit() needs to run softirqs if interrupts not active - in the
   previous patch it ran them when preempt_count() was 0, which is
   incorrect.
 - spinlock macros are updated to enable preemption after enabling
   interrupts. Besides avoiding false positive warnings, this also
 - fork.c has to call scheduler_tick() with preemption disabled -
   otherwise scheduler_tick()'s spin_unlock can preempt!
 - irqs_disabled() macro introduced.
 - [ all other local_irq_enable() or sti instances conditional on
     CONFIG_DEBUG_IRQ_SCHEDULE are to fix false positive warnings. ]
 - fix buggy in_softirq(). Fortunately the bug made the test broader,
   which didnt result in algorithmical breakage, just suboptimal
   performance.
 - move do_softirq() processing into irq_exit() => this also fixes the
   softirq processing bugs present in apic.c IRQ handlers that did not
   test for softirqs after irq_exit().
 - simplify local_bh_enable().

1 files changed, 7 insertions, 14 deletions

diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h
index d9f4af4103e4..749d3054b2dc 100644
--- a/include/linux/spinlock.h
+++ b/include/linux/spinlock.h
@@ -26,17 +26,17 @@
 #define write_lock_irq(lock)			do { local_irq_disable();        write_lock(lock); } while (0)
 #define write_lock_bh(lock)			do { local_bh_disable();         write_lock(lock); } while (0)
 
-#define spin_unlock_irqrestore(lock, flags)	do { spin_unlock(lock);  local_irq_restore(flags); } while (0)
+#define spin_unlock_irqrestore(lock, flags)	do { _raw_spin_unlock(lock);  local_irq_restore(flags); preempt_enable(); } while (0)
 #define _raw_spin_unlock_irqrestore(lock, flags) do { _raw_spin_unlock(lock);  local_irq_restore(flags); } while (0)
-#define spin_unlock_irq(lock)			do { spin_unlock(lock);  local_irq_enable();       } while (0)
-#define spin_unlock_bh(lock)			do { spin_unlock(lock);  local_bh_enable();        } while (0)
+#define spin_unlock_irq(lock)			do { _raw_spin_unlock(lock);  local_irq_enable(); preempt_enable();       } while (0)
+#define spin_unlock_bh(lock)			do { spin_unlock(lock); local_bh_enable(); } while (0)
 
-#define read_unlock_irqrestore(lock, flags)	do { read_unlock(lock);  local_irq_restore(flags); } while (0)
-#define read_unlock_irq(lock)			do { read_unlock(lock);  local_irq_enable();       } while (0)
+#define read_unlock_irqrestore(lock, flags)	do { _raw_read_unlock(lock);  local_irq_restore(flags); preempt_enable(); } while (0)
+#define read_unlock_irq(lock)			do { _raw_read_unlock(lock);  local_irq_enable(); preempt_enable(); } while (0)
 #define read_unlock_bh(lock)			do { read_unlock(lock);  local_bh_enable();        } while (0)
 
-#define write_unlock_irqrestore(lock, flags)	do { write_unlock(lock); local_irq_restore(flags); } while (0)
-#define write_unlock_irq(lock)			do { write_unlock(lock); local_irq_enable();       } while (0)
+#define write_unlock_irqrestore(lock, flags)	do { _raw_write_unlock(lock); local_irq_restore(flags); preempt_enable(); } while (0)
+#define write_unlock_irq(lock)			do { _raw_write_unlock(lock); local_irq_enable(); preempt_enable();       } while (0)
 #define write_unlock_bh(lock)			do { write_unlock(lock); local_bh_enable();        } while (0)
 #define spin_trylock_bh(lock)			({ int __r; local_bh_disable();\
 						__r = spin_trylock(lock);      \
@@ -135,12 +135,6 @@ do { \
 	preempt_enable(); \
 } while (0)
 
-#define spin_unlock_no_resched(lock) \
-do { \
-	_raw_spin_unlock(lock); \
-	preempt_enable_no_resched(); \
-} while (0)
-
 #define read_lock(lock)		({preempt_disable(); _raw_read_lock(lock);})
 #define read_unlock(lock)	({_raw_read_unlock(lock); preempt_enable();})
 #define write_lock(lock)	({preempt_disable(); _raw_write_lock(lock);})
@@ -153,7 +147,6 @@ do { \
 #define spin_lock(lock)			_raw_spin_lock(lock)
 #define spin_trylock(lock)		_raw_spin_trylock(lock)
 #define spin_unlock(lock)		_raw_spin_unlock(lock)
-#define spin_unlock_no_resched(lock)	_raw_spin_unlock(lock)
 
 #define read_lock(lock)			_raw_read_lock(lock)
 #define read_unlock(lock)		_raw_read_unlock(lock)