Re: [PATCH] util/interval-tree: Avoid race conditions without optimization

[Richard Henderson]

On 7/13/23 12:32, Peter Maydell wrote:
> On Fri, 7 Jul 2023 at 11:30, Richard Henderson
> <richard.henderson@linaro.org> wrote:
> > Read the left and right trees once, so that the gating
> > tests are meaningful.  This was only a problem at -O0,
> > where the compiler didn't CSE the two reads.
> >
> > Cc: qemu-stable@nongnu.org
> > Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
>
> Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
>
> If this data structure is intended to support operations
> being done on it while it's being mutated, shouldn't it
> be using the atomic accessors, though? That would make
> it clearer that you can't just undo the transformation
> made by this patch.

Yes, it probably should.  I use qatomic_set() where the kernel used WRITE_ONCE, but there 
was no markup for the read side.


r~