2007/2/9, Mulyadi Santosa <mulyadi.santosa@xxxxxxxxx>:
Hi Dong Feng > My understanding is that a *sleep* operation may cause block, but a > *wake-up* operation never. And I heard that it is safe to invoke > printk() in an interrupt handler. Of course not put printk() in > __switch_to(), but that seems because of some other reason. Maybe you're right. My other idea is, since printk deals with console output, maybe if you are doing it inside an interrupt handler that directly or indirectly deal with console, then it will trigger oops. Just another 2 cents speculation.
Yes, printk() deals with console. But I guess it does not always but only when it is safe to do that. If the context does not allow console-interaction, the printk() simply put the logged message to a memory buffer and wait for a user space process move the message out later. Not confirm by code in details. :-) So welcome other's comments.
regards, Mulyadi
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