From: David Mosberger <davidm@napali.hpl.hp.com>
Care needs to be taken when taking the address of a CPU-local
variable, because otherwise things may break when comparing addresses
on a platform which uses virtual remapping to implement such
variables. In particular, it's almost always unsafe to use the
address of a per-CPU variable which contains a "struct list", because
the list-manipulation routines use the list-head address to detect the
end of the list etc.
The patch below makes 2.5.74+ work on ia64 by reverting to the old
definition of this_rq(). Ditto for kernel/timer.c.
kernel/sched.c | 2 +-
kernel/timer.c | 8 ++++----
2 files changed, 5 insertions(+), 5 deletions(-)
diff -puN kernel/sched.c~ia64-percpu-revert kernel/sched.c
--- 25/kernel/sched.c~ia64-percpu-revert 2003-07-09 16:13:04.000000000 -0700
+++ 25-akpm/kernel/sched.c 2003-07-09 16:13:04.000000000 -0700
@@ -176,7 +176,7 @@ struct runqueue {
static DEFINE_PER_CPU(struct runqueue, runqueues);
#define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
-#define this_rq() (&__get_cpu_var(runqueues))
+#define this_rq() (cpu_rq(smp_processor_id())) /* not __get_cpu_var(runqueues)! */
#define task_rq(p) cpu_rq(task_cpu(p))
#define cpu_curr(cpu) (cpu_rq(cpu)->curr)
#define rt_task(p) ((p)->prio < MAX_RT_PRIO)
diff -puN kernel/timer.c~ia64-percpu-revert kernel/timer.c
--- 25/kernel/timer.c~ia64-percpu-revert 2003-07-09 16:13:04.000000000 -0700
+++ 25-akpm/kernel/timer.c 2003-07-09 16:13:04.000000000 -0700
@@ -160,7 +160,7 @@ static void internal_add_timer(tvec_base
*/
void add_timer(struct timer_list *timer)
{
- tvec_base_t *base = &get_cpu_var(tvec_bases);
+ tvec_base_t *base = &per_cpu(tvec_bases, get_cpu());
unsigned long flags;
BUG_ON(timer_pending(timer) || !timer->function);
@@ -171,7 +171,7 @@ void add_timer(struct timer_list *timer)
internal_add_timer(base, timer);
timer->base = base;
spin_unlock_irqrestore(&base->lock, flags);
- put_cpu_var(tvec_bases);
+ put_cpu();
}
/***
@@ -234,7 +234,7 @@ int mod_timer(struct timer_list *timer,
return 1;
spin_lock_irqsave(&timer->lock, flags);
- new_base = &__get_cpu_var(tvec_bases);
+ new_base = &per_cpu(tvec_bases, smp_processor_id());
repeat:
old_base = timer->base;
@@ -792,7 +792,7 @@ seqlock_t xtime_lock __cacheline_aligned
*/
static void run_timer_softirq(struct softirq_action *h)
{
- tvec_base_t *base = &__get_cpu_var(tvec_bases);
+ tvec_base_t *base = &per_cpu(tvec_bases, smp_processor_id());
if (time_after_eq(jiffies, base->timer_jiffies))
__run_timers(base);
_