Ingo Molnar wrote:
> On Wed, 24 Jul 2002, Christoph Hellwig wrote:
> > > - move the irqs-off check into preempt_schedule() and remove
> > > CONFIG_DEBUG_IRQ_SCHEDULE.
> > the config.in entry is still present..
> indeed. Fix is in -H5:
We need to verify correct usage of the
irq_enable/irq_restore() least we miss a preemption. The
attached patch allows one to enable a test on the these
macros to verify that they are being correctly used.
Ingo, I am not sure about the change in fork.c. Don't we
always want to check for preemption at the end of this
irq_disable?
Patch is against Ingo's H6.
--
George Anzinger geo...@mvista.com
High-res-timers:
http://sourceforge.net/projects/high-res-timers/
Real time sched: http://sourceforge.net/projects/rtsched/
Preemption patch:
http://www.kernel.org/pub/linux/kernel/people/rml
[
irq-test-2.5.27-ingo-H6.patch 6K ]
diff -urP -I \$Id:.*Exp \$ -X /usr/src/patch.exclude linux-2.5.27-ingo-H6-org/arch/i386/config.in linux/arch/i386/config.in
--- linux-2.5.27-ingo-H6-org/arch/i386/config.in Mon Jul 22 14:19:20 2002
+++ linux/arch/i386/config.in Wed Jul 24 12:13:56 2002
@@ -412,6 +412,7 @@
bool 'Kernel debugging' CONFIG_DEBUG_KERNEL
if [ "$CONFIG_DEBUG_KERNEL" != "n" ]; then
+ bool ' Debug IRQ preempt interaction' CONFIG_DEBUG_IRQ
bool ' Debug memory allocations' CONFIG_DEBUG_SLAB
bool ' Memory mapped I/O debugging' CONFIG_DEBUG_IOVIRT
bool ' Magic SysRq key' CONFIG_MAGIC_SYSRQ
diff -urP -I \$Id:.*Exp \$ -X /usr/src/patch.exclude linux-2.5.27-ingo-H6-org/include/asm-i386/system.h linux/include/asm-i386/system.h
--- linux-2.5.27-ingo-H6-org/include/asm-i386/system.h Wed Jul 24 12:50:03 2002
+++ linux/include/asm-i386/system.h Wed Jul 24 12:36:08 2002
@@ -312,9 +312,26 @@
/* interrupt control.. */
#define local_save_flags(x) __asm__ __volatile__("pushfl ; popl %0":"=g" (x): /* no input */)
-#define local_irq_restore(x) __asm__ __volatile__("pushl %0 ; popfl": /* no output */ :"g" (x):"memory", "cc")
+#define _local_irq_restore(x) __asm__ __volatile__("pushl %0 ; popfl": /* no output */ :"g" (x):"memory", "cc")
#define local_irq_disable() __asm__ __volatile__("cli": : :"memory")
-#define local_irq_enable() __asm__ __volatile__("sti": : :"memory")
+#define _local_irq_enable() __asm__ __volatile__("sti": : :"memory")
+#ifdef CONFIG_DEBUG_IRQ
+#define test_preempt() if (unlikely(! current_thread_info()->preempt_count)){ \
+ printk("bad: irq_restore() with preemption_enabled!\n");\
+ show_stack(NULL); }
+#else
+#define test_preempt()
+#endif
+#define local_irq_enable() \
+ do { _local_irq_enable(); test_preempt(); } while(0)
+#define local_irq_restore(x) \
+ do { _local_irq_restore(x); test_preempt(); } while(0)
+#define local_irq_enable_preempt() \
+ do { _local_irq_enable(); preempt_check_resched() ; } while(0)
+#define local_irq_restore_preempt(x) \
+ do { _local_irq_restore(x); preempt_check_resched(); } while(0)
+
+
/* used in the idle loop; sti takes one instruction cycle to complete */
#define safe_halt() __asm__ __volatile__("sti; hlt": : :"memory")
diff -urP -I \$Id:.*Exp \$ -X /usr/src/patch.exclude linux-2.5.27-ingo-H6-org/include/linux/spinlock.h linux/include/linux/spinlock.h
--- linux-2.5.27-ingo-H6-org/include/linux/spinlock.h Wed Jul 24 12:50:03 2002
+++ linux/include/linux/spinlock.h Wed Jul 24 12:39:39 2002
@@ -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 { _raw_spin_unlock(lock); local_irq_restore(flags); preempt_enable(); } while (0)
+#define spin_unlock_irqrestore(lock, flags) do { _raw_spin_unlock(lock); local_irq_restore_preempt(flags); } 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 { _raw_spin_unlock(lock); local_irq_enable(); preempt_enable(); } while (0)
+#define spin_unlock_irq(lock) do { _raw_spin_unlock(lock); local_irq_enable_preempt(); } while (0)
#define spin_unlock_bh(lock) do { spin_unlock(lock); local_bh_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_irqrestore(lock, flags) do { _raw_read_unlock(lock); local_irq_restore_preempt(flags); } while (0)
+#define read_unlock_irq(lock) do { _raw_read_unlock(lock); local_irq_enable_preempt(); } while (0)
#define read_unlock_bh(lock) do { read_unlock(lock); local_bh_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_irqrestore(lock, flags) do { _raw_write_unlock(lock); local_irq_restore_preempt(flags); } while (0)
+#define write_unlock_irq(lock) do { _raw_write_unlock(lock); local_irq_enable_preempt(); } 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); \
diff -urP -I \$Id:.*Exp \$ -X /usr/src/patch.exclude linux-2.5.27-ingo-H6-org/kernel/fork.c linux/kernel/fork.c
--- linux-2.5.27-ingo-H6-org/kernel/fork.c Wed Jul 24 12:50:03 2002
+++ linux/kernel/fork.c Wed Jul 24 12:46:52 2002
@@ -753,10 +753,8 @@
current->time_slice = 1;
preempt_disable();
scheduler_tick(0, 0);
- local_irq_restore(flags);
- preempt_enable();
- } else
- local_irq_restore(flags);
+ }
+ local_irq_restore_preempt(flags);
/*
* Ok, add it to the run-queues and make it
diff -urP -I \$Id:.*Exp \$ -X /usr/src/patch.exclude linux-2.5.27-ingo-H6-org/kernel/sched.c linux/kernel/sched.c
--- linux-2.5.27-ingo-H6-org/kernel/sched.c Wed Jul 24 12:50:03 2002
+++ linux/kernel/sched.c Wed Jul 24 12:12:02 2002
@@ -907,6 +907,7 @@
printk("bad: schedule() with irqs disabled!\n");
show_stack(NULL);
preempt_enable_no_resched();
+ return;
}
need_resched:
diff -urP -I \$Id:.*Exp \$ -X /usr/src/patch.exclude linux-2.5.27-ingo-H6-org/mm/slab.c linux/mm/slab.c
--- linux-2.5.27-ingo-H6-org/mm/slab.c Wed Jul 24 12:50:03 2002
+++ linux/mm/slab.c Wed Jul 24 12:38:27 2002
@@ -1386,9 +1386,8 @@
} else {
STATS_INC_ALLOCMISS(cachep);
objp = kmem_cache_alloc_batch(cachep,flags);
- local_irq_restore(save_flags);
/* end of non-preemptible region */
- preempt_enable();
+ local_irq_restore_preempt(save_flags);
if (!objp)
goto alloc_new_slab_nolock;
return objp;
by