Re: [uml-devel] SIGSEGV and SA_NODEFER

[Jeff Dike <jdike@addtoit.com>]

blaisorblade@yahoo.it said:
> Are we sure it is a compensation? I started having the doubt that
> enabling the  signal inside the handler is not the same thing...
> because otherwise we don't  understand why the patch in 2.4 makes
> difference in TT mode.

Well, it clearly does something very close to SA_NODEFER, so it's compensation
in that sense.

> Indeed, the blocking is done in the same way, but probably the timing
> is  different - i.e. we unblock the signal only after
> unprotect_kernel_mem() in  the new code, which somehow *makes* a
> difference.

Maybe.  If unprotect_kernel_mem has anything to do with it, then it can
only affect jail mode in tt, which I'm planning on doing away with anyway
at some point.

> I'm going to choose the SA_NODEFER instead of adding the explicit
> check, at  least for 2.4. I'd do it for 2.6 too, only that I'm not too
> sure. 

My preference would be SA_NODEFER.  Do we know who was having problems that
were fixed by this?  Maybe we could see what exactly SA_NODEFER does there.

				Jeff



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