Why kernel code/thread executing in interrupt context cannot sleep?

Question

I am reading following article by Robert Love

http://www.linuxjournal.com/article/6916

that says

\"...Let\'s discuss the fact that work queues run i

Answer 1

The linux kernel has two ways to allocate interrupt stack. One is on the kernel stack of the interrupted process, the other is a dedicated interrupt stack per CPU. If the interrupt context is saved on the dedicated interrupt stack per CPU, then indeed the interrupt context is completely not associated with any process. The "current" macro will produce an invalid pointer to current running process, since the "current" macro with some architecture are computed with the stack pointer. The stack pointer in the interrupt context may point to the dedicated interrupt stack, not the kernel stack of some process.