Andrew Morton wrote:
>
> Jun Sun wrote:
> >
> > BTW, I really think interrupt handlers acquiring the same locks which
> > can be acquired by processes is a *BIG* problem in Linux. We should fix
> > this problem. Unfortunately I am not familiar with Linux kernel well
> > enough to offer a solution.
>
> Why do you think this? Any specific examples in mind?
>
Linus told me so. I believe him. :-)
I did sniff around the source code and spotted a couple of places where
locks COULD be acquired by ISRs, but I never did a RUN-TIME check to
catch this situation.
Apparently Rik seems to confirm that. See his reply.
---I believe the problem here is that Linux does not have a CLEAR notion and separation of task-context code and interrupt-context code.
Imagine if a kernel function needs to read task list, then it must acquire a read lock on tasklist_lock. However, the function might be called from both process and ISR, then we will have the ISR acquiring lock problem.
I don't know if this has been a problem to Linux in the past. I am relatively new to Linux kernel.
Jun
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