How to debug ARM Linux kernel (msleep ())?

If it msleep

doesn't return or jump to schedule

, then we can follow the call stack for debugging.

msleep

calls schedule_timeout_uninterruptible(timeout)

that calls schedule_timeout(timeout)

, which in the default case exits without calling the schedule if the timeout in the jiffies passed to it is <0, so that's one thing to check.

If timeout

positive, called setup_timer_on_stack(&timer, process_timeout, (unsigned long)current);

, then __mod_timer(&timer, expire, false, TIMER_NOT_PINNED);

before the call schedule

.

If we don't get to schedule

, then something must be happening in setup_timer_on_stack

either __mod_timer

.

Calltrace for setup_timer_on_stack

are setup_timer_on_stack

calls setup_timer_on_stack_key

that call init_timer_on_stack_key

, either external, if CONFIG_DEBUG_OBJECTS_TIMERS

enabled, or call init_timer_key(timer, name, key);

, which calls debug_init

, followed by __init_timer(timer, name, key)

.

__mod_timer

calls first timer_stats_timer_set_start_info(timer);

, then a whole series of other function calls.

I would suggest starting by putting a printk or two in schedule_timeout

, perhaps either side of the call setup_timer_on_stack

or either side of the call __mod_timer

.