Re: sharing data

[Tyler <tyler@xxxxxxxx>]

> 1. I share a data between a kernel thread and an ISR. ( this is a 
> uniprocessor system). In kernel thread I do spin_lock_irqsave
>
>  and then unlocking. Where as accessing the data from the ISR I do not 
> use any spin lock coz I know when the ISR is running the kernel thread 
> does not get a chance to run. Am I right ???
It is only true if you are not in a SMP environment (and think of those 
who have multiprocessors) and also if you are not in a preemptive 
envirnoment (Linux kernel is preemptive since 2.5). So you should 
protect your data in the ISR too.
> 2. I want to implement a message quque send and recv routine between two 
> kernel threads. ( here I can not use the standard message quques)
>
> What I do is in recv call I check if there is any message in the queue. 
> If no then I sleep on a wait queue.
>
> While sending a message I always add the message to the queue and and 
> use wake up call on wait queue.
>
> Is my implementation leak proff…..or there are some flaws???

Yes it looks good :)




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