Re: [PATCH 8/9] perf/breakpoint: Split breakpoint "check" and "commit"

Joel Fernandes
2018-05-07T00:46:21Z

On Sun, May 6, 2018 at 12:22 PM Frederic Weisbecker <frederic@kernel.org>
wrote:

> arch_validate_hwbkpt_settings() mixes up attribute check and commit into
> a single code entity. Therefore the validation may return an error due to
> incorrect atributes while still leaving halfway modified architecture
> breakpoint struct.

> Now that we have split its logic on all archs, we can remove this
> misdesigned function and call directly the arch check and commit
> functions instead. This allows us to later avoid commiting
> a breakpoint to architecture when its slot couldn't be allocated.

[...]
> diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c
> index 6e28d28..6896ceeb 100644
> --- a/kernel/events/hw_breakpoint.c
> +++ b/kernel/events/hw_breakpoint.c
> @@ -402,11 +402,12 @@ int dbg_release_bp_slot(struct perf_event *bp)

> static int validate_hw_breakpoint(struct perf_event *bp)
> {
> - int ret;
> + int err;

> - ret = arch_validate_hwbkpt_settings(bp);
> - if (ret)
> - return ret;
> + err = hw_breakpoint_arch_check(bp, &bp->attr);
> + if (err)
> + return err;
> + hw_breakpoint_arch_commit(bp);

minor nit:
To preserve bisectability, shouldn't this be the following in this and
earlier patches?

err = hw_breakpoint_arch_check(bp, &bp->attr);
hw_breakpoint_arch_commit(bp);
if (err)
return err;

And then in patch 9/9 you can fix it the right way?

thanks,

- Joel