[LIP] Question about Linux kernel

Is Linux kernel pre-emptive ?

I have a question about Linux kernel. I am writing a char driver, in which I
have implemented my own queues for reader and writer. I don't know if such
queues are already available in Linux.

Whenever my driver receives interrupt from device, it gets the packet from
devices memory and enqueues into the Rx queue.

In the device_read call, i want to dequeue packet from this queue and want
to send it to user using copy_to_user.

How do I take care of mutual exclusion here ? One obvious thing is whenever
ISR is getting executed I am sure its an atomic operation and my reader
process will not get chance to run, but I don't know what will happen if an
interrupt comes while reader is dequeueing the packet from the queue.

How can I make enqueue and dequeue functions atomic ?

Thanks in advance.

Regards,
Rakesh

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