Re: [PATCH] bpf: remove pointless code from bpf_do_trace_printk()

[Florent Revest]

On Thu, Apr 22, 2021 at 5:44 PM Alexei Starovoitov
<alexei.starovoitov@xxxxxxxxx> wrote:
>
> On Thu, Apr 22, 2021 at 8:35 AM Florent Revest <revest@xxxxxxxxxxxx> wrote:
> > >
> > > I was having a stroll through lib/vsprintf.c and noticed bstr_printf:
> > >
> > >  * This function like C99 vsnprintf, but the difference is that vsnprintf gets
> > >  * arguments from stack, and bstr_printf gets arguments from @bin_buf which is
> > >  * a binary buffer that generated by vbin_printf.
> > >
> > > Maybe it would be easier to just build our argument buffer similarly
> > > to what vbin_printf does.
> >
> > I've been experimenting with this idea and it is quite promising :) it
> > also makes the code much cleaner, I find. I'll send a series asap.
>
> You mean to use bstr_printf internally ? That could work indeed.
> Make sure CONFIG_BINARY_PRINTF is selected.
> CONFIG_TRACING does it already.

Yes :)

> > BPF maintainers: should we fix forward or do you prefer reverting the
> > snprintf series and then re-applying another snprintf series without
> > the regression in bpf_trace_printk that mangles some argument types ?
> > (bpf_seq_printf has always been like that so no regression there)
>
> Pls send it as a follow up.
> Along with another patch to clean verifier bits we discussed.
> The merge window is approaching, so it has to be done asap.

On it ;)