RE: ftrace histogram sorting broken on BE architecures

David Laight
2019-12-17T10:06:03Z

From: Steven Rostedt
> Sent: 16 December 2019 18:29
> On Mon, 16 Dec 2019 17:06:50 +0000
> David Laight <David.Laight@ACULAB.COM> wrote:
>
> > > Where original_val_a could be a byte, short, int, long or long long.
> >
> > I'd sort of guessed that, but then the pointer type passed to tracing_map_cmp_##type()
> > will always be 'u64 *' (since the field the address is taken of must be that type).
> > Then the (u64 *) casts are no longer needed.
> >
> > Possibly you can just pass the u64 values to:
> > tracing_map_cmp_##type(type a, type b)
> > {
> > return a > b ? 1 : a < b ? -1 : 0;
> > }
> >
> > The high bit masking and sign extension is then implicit in the call.
>
> But these are used to pass into a compare function that takes compare
> functions that are something other than numbers. They can be pointers
> to strings.

In that case I think I'd embed the u64 inside a structure and pass the structure
address to the compare function.

David

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