Re: [LIP] Question about Linux kernel

Linux-2.6 _is_ pre-emptive (if configured so).  Robert Love's 'Linux
Kernel Development' convers 2.6 kernel -- it's a good book.

Rakesh Avichal Ughreja said:
> 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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/----------------------------------------------|
| R. Sridhar                                   |
| WWW: http://cs.annauniv.edu/~rsridhar        |
|----------------------------------------------/


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