Re: [PATCH] binfmt_elf: core dump masking support

[Pavel Machek <pavel@ucw.cz>]

On Tue 2007-01-23 13:42:00, Kawai, Hidehiro wrote:
> Hi,
> 
> >>>(run echo 1 > coremask, echo 0 > coremask in a loop while dumping
> >>>core. Do you have enough locking to make it work as expected?)
> >>
> >>Currently, any lock isn't acquired.  But I think the kernel only
> >>have to preserve the coremask setting in a local variable at the
> >>begining of core dumping.  I'm going to do this in the next version.
> > 
> > No, I do not think that is enough. At minimum, you'd need atomic_t
> > variable. But I'd recomend against it. Playing with locking is tricky.
> 
> Why do you think it is not enough?  I think that any locking is not
> needed.

You are wrong.

>   unsigned int mask = current->mm->coremask;

Not a valid C; coremask can change from another cpu.

							Pavel
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