From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F31BCC432BE for ; Tue, 31 Aug 2021 00:38:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C39D861004 for ; Tue, 31 Aug 2021 00:38:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239131AbhHaAjF (ORCPT ); Mon, 30 Aug 2021 20:39:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48412 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231989AbhHaAjC (ORCPT ); Mon, 30 Aug 2021 20:39:02 -0400 Received: from mail-yb1-xb2c.google.com (mail-yb1-xb2c.google.com [IPv6:2607:f8b0:4864:20::b2c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B553AC061575; Mon, 30 Aug 2021 17:38:07 -0700 (PDT) Received: by mail-yb1-xb2c.google.com with SMTP id e129so31633678yba.5; Mon, 30 Aug 2021 17:38:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=dIoCwE46sRweXCxYQ2GXPb1y5Z88T5kmd3WMggOIQlM=; b=C6WzzhEIa5tkiDWnP3ym+GCLUImj02sSwGurz0W6JfMrbtFPZjckdOW9JbSeAzdaAV AtPwUXpxVShsYGTxB9UhtWr4Zo4iC/r6JQclZInmZOzxWasR5AIjU/XTJdJrs90McPzf x+9AMAqZwJZcCQbEWXKMRq2K9VknG3kaOmIW0WbGC/Xw6WpK/44PuCR/Lk/+I0vooMAF x5xVJur/sFD263w1kQ4uWX8MD5lFptG5mPh/5dDIRAaeJqD2blUDXXOuL9dqiRT8S/JH h81OuB0R8f6GvLqu+imHUFaBNHZoFM5AxHo6IXJhUzkKiYV13YseDoZCy/SyD/ZJWh/u AXgA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=dIoCwE46sRweXCxYQ2GXPb1y5Z88T5kmd3WMggOIQlM=; b=im2nGHqe3Wxb6BK1wTWSROYfYJ720G1zhyDF1un7Lg7Sco/vgWGm2w0ORXZSYBAGaI OxcLg3ihOAI4olROppr/nDyyYORu/QS5jDnc8VhAWbAhWUWLwtFnXf1CZwawCKqc8BVW kCwc69l+uWB20GaGs7ZyU8MTkDhzehe6pbRERFLXgtlh+/ZVWTk+hquYgYUM/LxyaKBY MCrAfUOHW7IuAZMTM1ju8++N7FLKFubh5IJhlO/EHFPMvzKDSO71DZMtpqfamB20lcdf GmfzymuDVP5dUG9JoFuUVpO50Hf4fqzylp8jrI3AHdyOmjsj0Lpijg07Xc8Ekb3W6cK7 ew+A== X-Gm-Message-State: AOAM533ZTJZmC5EiIa2fxkzwHbbBBx2EOa8AHGdbcEwQBXjE1aMnyEQi DfA3xYcOlpRvbQjYpxtQpAY4XJyMy0Odv7pYKOEW2FuQ X-Google-Smtp-Source: ABdhPJxeMygX7oYWfVfD8GI1jlPX2zWgC/Q1jXddRHXB0y2VFfDm3QhGq4IOGRbcJ56FB2pcnlXuK2JkA+pjetlFZKA= X-Received: by 2002:a25:4941:: with SMTP id w62mr26991045yba.230.1630370286948; Mon, 30 Aug 2021 17:38:06 -0700 (PDT) MIME-Version: 1.0 References: <20210828052006.1313788-1-davemarchevsky@fb.com> <20210828052006.1313788-5-davemarchevsky@fb.com> In-Reply-To: <20210828052006.1313788-5-davemarchevsky@fb.com> From: Andrii Nakryiko Date: Mon, 30 Aug 2021 17:37:56 -0700 Message-ID: Subject: Re: [PATCH v3 bpf-next 4/7] libbpf: use static const fmt string in __bpf_printk To: Dave Marchevsky Cc: bpf , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Yonghong Song , Networking Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Fri, Aug 27, 2021 at 10:20 PM Dave Marchevsky wrote: > > The __bpf_printk convenience macro was using a 'char' fmt string holder > as it predates support for globals in libbpf. Move to more efficient > 'static const char', but provide a fallback to the old way via > BPF_NO_GLOBAL_DATA so users on old kernels can still use the macro. > > Signed-off-by: Dave Marchevsky > --- > tools/lib/bpf/bpf_helpers.h | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h > index 5f087306cdfe..a1d5ec6f285c 100644 > --- a/tools/lib/bpf/bpf_helpers.h > +++ b/tools/lib/bpf/bpf_helpers.h > @@ -216,10 +216,16 @@ enum libbpf_tristate { > ___param, sizeof(___param)); \ > }) > > +#ifdef BPF_NO_GLOBAL_DATA > +#define BPF_PRINTK_FMT_TYPE char > +#else > +#define BPF_PRINTK_FMT_TYPE static const char > +#endif > + > /* Helper macro to print out debug messages */ > #define __bpf_printk(fmt, ...) \ > ({ \ > - char ____fmt[] = fmt; \ > + BPF_PRINTK_FMT_TYPE ____fmt[] = fmt; \ personal preferences, of course, but I'd leave char right there (I think it makes it a bit more obvious what's going on right there), and s/BPF_PRINTK_FMT_TYPE/BPF_PRINTK_FMT_MOD/ and have it as either "" or "static const". > bpf_trace_printk(____fmt, sizeof(____fmt), \ > ##__VA_ARGS__); \ > }) > -- > 2.30.2 >