Is printk atomic-safe?

Question

Is it safe to call printk from an atomic context, e.g. an IRQ?

Answer 1

Yes, it's explicitly allowed to use it in atomic context; the function is in fact very robust since it may also be called at panic time.

printk will just try to lock the console to print the message; if the lock is already taken then the output is queued to a buffer but the function will never block.