Re: [PATCH 5/5] uio: Implement hotunplug support, using libunload

[Eric W. Biederman]

"Hans J. Koch" <hjk@xxxxxxxxxxxxx> writes:

> On Sun, Sep 26, 2010 at 03:49:03PM -0700, Eric W. Biederman wrote:
>> 
>> With this change it is possible to remove a module that implements
>> a uio device, or to remove the underlying hardware device of a uio
>> device withot crashing the kernel, or causing user space more problems
>> than just an I/O error.
>
> Well, that I/O error can also be a segfault if userspace accesses
> memory previously mmap'ed. So a userspace program needs to properly
> handle -EIO from read(), and has to handle SIG_SEGV. 

It is SIG_BUS (just like truncate), but yes.  If userspace doesn't
handle there error it can go down.  All of which is a better state
then the current version where the kernel crash if you hotunplug
a uio device.

> This should also
> be mentioned in Documentation/DocBook/uio-howto.tmpl.
> Or do you have a better solution?

A better solution for?

Eric
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