* Daniel Walker <[EMAIL PROTECTED]> wrote:
> In the interest of CC'ing everyone here's another patch .
>
> This checks for wake_up_process() calls inside was preempt off
> sections. So if it was a spinlock , and you call wake_up_process() it
> will trigger a warning.. These are problematic cause in RT the
> wake_up_process() (if it's an RT task) will cause a context switch
> immediately , but with out RT you don't context switch till you unlock
> the last spinlock ..
this certainly makes sense, a 'naked' wakeup is almost certainly a bug.
I've applied your patch, and have released the -52-13 PREEMPT_RT
patchset. [ But please be more careful with the coding style next time,
see below the number of fixups i had to do relative to your patch
(whitespaces, line length, code structure format, etc.). ]
> There is also some checking on lock_depth , includes all types of
> locks that are not rt_mutex types. I noticed that my test system went
> to lock depth ~17 !
i've further upped the lock depth from 20 to 25 - if 17 happens then 20
is most likely not enough.
Ingo
--- linux/kernel/rt.c.orig
+++ linux/kernel/rt.c
@@ -251,11 +251,11 @@ void zap_rt_locks(void)
#ifdef CONFIG_DEBUG_PREEMPT
int check_locking_preempt_off(struct task_struct *p)
{
- int i = 0;
+ int i;
- for (;i < p->lock_count; i++) {
- if (p->owned_lock[i]->was_preempt_off) return 1;
- }
+ for (i = 0; i < p->lock_count; i++)
+ if (p->owned_lock[i]->was_preempt_off)
+ return 1;
return 0;
}
@@ -264,17 +264,18 @@ void check_preempt_wakeup(struct task_st
/*
* Possible PREEMPT_RT race scenario when
* wake_up_proces() is usually called with
- * preemption off , but PREEMPT_RT enables
+ * preemption off, but PREEMPT_RT enables
* it. If the task is dependent on preventing
* context switches either with spinlocks
- * or rcu locks , then this could result in
+ * or rcu locks, then this could result in
* hangs and race conditions.
*/
- if (!preempt_count() &&
+ if (!preempt_count() &&
p->prio < current->prio &&
rt_task(p) &&
(current->rcu_read_lock_nesting != 0 ||
- check_locking_preempt_off(current)) ) {
+ check_locking_preempt_off(current))) {
+
printk("BUG: %s/%d, possible wake_up race on %s/%d\n",
current->comm, current->pid, p->comm, p->pid);
dump_stack();
@@ -917,10 +918,12 @@ void set_new_owner(struct rt_mutex *lock
lock->acquire_eip = eip;
#endif
#ifdef CONFIG_DEBUG_PREEMPT
- if (new_owner->task->lock_count < 0 || new_owner->task->lock_count >=
MAX_LOCK_STACK) {
+ if (new_owner->task->lock_count < 0 ||
+ new_owner->task->lock_count >= MAX_LOCK_STACK) {
TRACE_OFF();
- printk("BUG: %s/%d: lock count of %lu\n",
- new_owner->task->comm, new_owner->task->pid,
new_owner->task->lock_count);
+ printk("BUG: %s/%d: lock count of %lu\n",
+ new_owner->task->comm, new_owner->task->pid,
+ new_owner->task->lock_count);
dump_stack();
}
new_owner->task->owned_lock[new_owner->task->lock_count] = lock;
@@ -1055,7 +1058,7 @@ static int __grab_lock(struct rt_mutex *
#ifdef CONFIG_DEBUG_PREEMPT
if (owner->lock_count < 0 || owner->lock_count >= MAX_LOCK_STACK) {
TRACE_OFF();
- printk("BUG: %s/%d: lock count of %lu\n",
+ printk("BUG: %s/%d: lock count of %lu\n",
owner->comm, owner->pid, owner->lock_count);
dump_stack();
}
@@ -1370,7 +1373,7 @@ ____up_mutex(struct rt_mutex *lock, int
#ifdef CONFIG_DEBUG_PREEMPT
if (current->lock_count < 0 || current->lock_count >= MAX_LOCK_STACK) {
TRACE_OFF();
- printk("BUG: %s/%d: lock count of %lu\n",
+ printk("BUG: %s/%d: lock count of %lu\n",
current->comm, current->pid, current->lock_count);
dump_stack();
}
--- linux/kernel/sched.c.orig
+++ linux/kernel/sched.c
@@ -1567,6 +1567,7 @@ EXPORT_SYMBOL(wake_up_process);
int fastcall wake_up_process_sync(task_t * p)
{
int ret;
+
check_preempt_wakeup(p);
ret = try_to_wake_up(p, TASK_STOPPED | TASK_TRACED |
TASK_RUNNING_MUTEX | TASK_INTERRUPTIBLE |
--- linux/include/linux/init_task.h.orig
+++ linux/include/linux/init_task.h
@@ -63,12 +63,6 @@
extern struct group_info init_groups;
-#ifdef CONFIG_DEBUG_PREEMPT
-# define INIT_LOCK_COUNT(x) .lock_count = x,
-#else
-# define INIT_LOCK_COUNT(x)
-#endif
-
/*
* INIT_TASK is used to set up the first task table, touch at
* your own risk!. Base=0, limit=0x1fffff (=2MB)
@@ -80,7 +74,6 @@ extern struct group_info init_groups;
.usage = ATOMIC_INIT(2), \
.flags = 0, \
.lock_depth = -1, \
- INIT_LOCK_COUNT(0) \
.prio = MAX_PRIO-20, \
.static_prio = MAX_PRIO-20, \
.normal_prio = MAX_PRIO-20, \
--- linux/include/linux/sched.h.orig
+++ linux/include/linux/sched.h
@@ -58,8 +58,8 @@ extern int debug_direct_keyboard;
extern int check_locking_preempt_off(struct task_struct *p);
extern void check_preempt_wakeup(struct task_struct * p);
#else
-#define check_locking_preempt_off(x) (0)
-#define check_preempt_wakeup(p) do { } while(0)
+#define check_locking_preempt_off(x) 0
+#define check_preempt_wakeup(p) do { } while (0)
#endif
#ifdef CONFIG_RT_DEADLOCK_DETECT
@@ -898,7 +898,7 @@ struct task_struct {
/* Protection of proc_dentry: nesting proc_lock, dcache_lock,
write_lock_irq(&tasklist_lock); */
spinlock_t proc_lock;
-#define MAX_PREEMPT_TRACE 20
+#define MAX_PREEMPT_TRACE 25
#ifdef CONFIG_PREEMPT_TRACE
unsigned long preempt_trace_eip[MAX_PREEMPT_TRACE];
--- linux/include/linux/rt_lock.h.orig
+++ linux/include/linux/rt_lock.h
@@ -102,7 +102,7 @@ struct rt_mutex_waiter {
#ifdef CONFIG_DEBUG_PREEMPT
# define __WAS_PREEMPT_OFF(x) , .was_preempt_off = x
#else
-# define __WAS_PREEMPT_OFF(x) , .was_preempt_off = x
+# define __WAS_PREEMPT_OFF(x)
#endif
#ifdef CONFIG_RT_DEADLOCK_DETECT
@@ -133,7 +133,7 @@ struct rt_mutex_waiter {
#define __RT_MUTEX_INITIALIZER(lockname) \
{ .wait_lock = __RAW_SPIN_LOCK_UNLOCKED \
__PLIST_INIT(lockname) \
- __WAS_PREEMPT_OFF(0) \
+ __WAS_PREEMPT_OFF(0) \
__RT_MUTEX_DEADLOCK_DETECT_INITIALIZER(lockname) \
__RT_MUTEX_DEBUG_RT_LOCKING_MODE_INITIALIZER }
@@ -165,7 +165,7 @@ typedef struct {
.wait_lock = __RAW_SPIN_LOCK_UNLOCKED, .save_state = 1 \
__PLIST_INIT((lockname).lock.lock) \
, .file = __FILE__, .line = __LINE__ \
- __WAS_PREEMPT_OFF(1) \
+ __WAS_PREEMPT_OFF(1) \
__RT_MUTEX_DEBUG_RT_LOCKING_MODE_INITIALIZER
# define _RW_LOCK_UNLOCKED(lockname) \
(rwlock_t) { { { __RW_LOCK_UNLOCKED(lockname), .name = #lockname } } }
@@ -199,7 +199,7 @@ typedef struct {
.wait_lock = __RAW_SPIN_LOCK_UNLOCKED \
__PLIST_INIT(((lockname).lock)) \
, .save_state = 1, .file = __FILE__, .line = __LINE__ \
- __WAS_PREEMPT_OFF(1) \
+ __WAS_PREEMPT_OFF(1) \
__RT_MUTEX_DEBUG_RT_LOCKING_MODE_INITIALIZER
# define _SPIN_LOCK_UNLOCKED(lockname) \
(spinlock_t) { { __SPIN_LOCK_UNLOCKED(lockname), .name = #lockname } }
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
