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Subject[PATCH] show_task() and thread_saved_pc() fix for x86
	* thread_saved_pc() on x86 returns (thread->esp)[3]. Bogus, since the
third word from the stack top has absolutely nothing to return address of
any kind. Correct value: (thread->esp)[0][1] - ebp is on top of the stack
and the rest is obvious. Current code gives completely bogus addresses -
try to say Alt-SysRq-T and watch the show.

* kernel/sched::show_state() used the wrong check for process being
on some CPU - p==current is nice for UP, but on SMP it's obviously wrong.
Moroever, nothing prevents schedule() another CPU while we are going through
the process state. Fix: show_state() grabs runqueue_lock, show_task() checks
p->has_cpu instead of p == current.

Please, apply.
Cheers,
Al

diff -urN rc11-2/include/asm-i386/processor.h rc11-2-show_task/include/asm-i386/processor.h
--- rc11-2/include/asm-i386/processor.h Fri Nov 10 09:14:04 2000
+++ rc11-2-show_task/include/asm-i386/processor.h Fri Nov 10 16:08:15 2000
@@ -412,7 +412,7 @@
*/
extern inline unsigned long thread_saved_pc(struct thread_struct *t)
{
- return ((unsigned long *)t->esp)[3];
+ return ((unsigned long **)t->esp)[0][1];
}

unsigned long get_wchan(struct task_struct *p);
diff -urN rc11-2/kernel/sched.c rc11-2-show_task/kernel/sched.c
--- rc11-2/kernel/sched.c Fri Nov 10 09:18:43 2000
+++ rc11-2-show_task/kernel/sched.c Fri Nov 10 16:11:39 2000
@@ -1121,12 +1121,12 @@
else
printk(" ");
#if (BITS_PER_LONG == 32)
- if (p == current)
+ if (p->has_cpu)
printk(" current ");
else
printk(" %08lX ", thread_saved_pc(&p->thread));
#else
- if (p == current)
+ if (p->has_cpu)
printk(" current task ");
else
printk(" %016lx ", thread_saved_pc(&p->thread));
@@ -1186,6 +1186,7 @@
void show_state(void)
{
struct task_struct *p;
+ unsigned long flags;

#if (BITS_PER_LONG == 32)
printk("\n"
@@ -1196,10 +1197,12 @@
" free sibling\n");
printk(" task PC stack pid father child younger older\n");
#endif
+ spin_lock_irqsave(&runqueue_lock, flags);
read_lock(&tasklist_lock);
for_each_task(p)
show_task(p);
read_unlock(&tasklist_lock);
+ spin_unlock_irqrestore(&runqueue_lock, flags);
}

/*
-
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