Messages in this thread | | | Date | Mon, 08 Nov 2004 14:47:59 -0500 | From | Mike Waychison <> | Subject | Re: problem with printk-- somebody please help |
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Arun Srinivas wrote: > hi > > I am new to the kernel world and would be very glad if somebody could > help me with this problem. > > I am unable to do printk or even a macro call like rdtsc()...(for > reading the time stamp counter) from within the "activate_task" > function on a kernel with smp support.But these work under the main > schedule() function. > > I was able to do all these i.e., inside "activate_task" on a kernel > without smp support.Can anybody suggest a solution as to what could be > the problem?? > > somebody please help.
I seem to recall that doing so would deadlock your machine. activate_task is called with the given cpu's runqueue locked. printk eventually calls release_console_sem, which will wake_up_interruptible, which will eventually call try_to_wake_up which grabs the same lock.
I don't think I've ever seen printk work while task_rq_lock'ed.
Someone correct me if I'm wrong, this is the best I was able to figure out before giving up.
- -- Mike Waychison Sun Microsystems, Inc. 1 (650) 352-5299 voice 1 (416) 202-8336 voice
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