From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from todd.t-8ch.de (todd.t-8ch.de [159.69.126.157]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 04AD31DF963; Tue, 26 Nov 2024 21:42:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=159.69.126.157 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732657339; cv=none; b=fEwpqqgttsG+b6mu+xwfWzYb4vjkeH7hLIBedgmgK3Sl/V9Uq0e709gwAgtVpiTG0LIhhyBcGQV2xc7U2BCVQWk+85w7kNhDG2gmAXMtJPJxrvxMNVB9K9c09VEf2Biap0jao7T9ATjrdlPH3FUnW0AEARSoiHuAYZmrLfxiniY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732657339; c=relaxed/simple; bh=KLOxZqYqAMVocTruSnmp0YRWLPlKl6C/iQVIZbJW18w=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=jnxiD/KW27mxpWfJ8HTcS0MvJn+CCLaUF5UIZxL9eByJn+xiyVhz6Y4jO8zNzF7v1KpMgfZd5DAL4uCaeYI66AgrGtd9KzLOx8/PcEzwIlSGlS+hdVdyFLIZEaaLEtY1N0c61zp8reQIoqTJT0+98U1vKMJb/2PxtL8Yjn3h1kk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=weissschuh.net; spf=pass smtp.mailfrom=weissschuh.net; dkim=pass (1024-bit key) header.d=weissschuh.net header.i=@weissschuh.net header.b=nrfPjwbI; arc=none smtp.client-ip=159.69.126.157 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=weissschuh.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=weissschuh.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=weissschuh.net header.i=@weissschuh.net header.b="nrfPjwbI" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=weissschuh.net; s=mail; t=1732657336; bh=KLOxZqYqAMVocTruSnmp0YRWLPlKl6C/iQVIZbJW18w=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=nrfPjwbIU85kXd+xpm7HaeyT8NnV9bAFCG9ftOLTlHe9z8yvhTi6q04pTaUqxB21f xfpv1qTfFpSTbWAU5SupZhHT3CzHIX8/K91kSwGkslgxtoBYdHv2mt5pFA7RbLiDS+ awbYg+e7KKD3MjZX0D3m76rBlgeJfbDC9y6ipLbU= Date: Tue, 26 Nov 2024 22:42:15 +0100 From: Thomas =?utf-8?Q?Wei=C3=9Fschuh?= To: Andrii Nakryiko Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , bpf@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] btf: Use BIN_ATTR_SIMPLE_RO() to define vmlinux attribute Message-ID: <5307ea3b-6720-4ca9-827e-7338f255908f@t-8ch.de> References: <20241122-sysfs-const-bin_attr-bpf-v1-1-823aea399b53@weissschuh.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On 2024-11-26 13:37:26-0800, Andrii Nakryiko wrote: > On Fri, Nov 22, 2024 at 4:57 AM Thomas Weißschuh wrote: > > > > The usage of the macro allows to remove the custom handler function, > > saving some memory. Additionally the code is easier to read. > > > > Signed-off-by: Thomas Weißschuh > > --- > > Something similar can be done to btf_module_read() in kernel/bpf/btf.c. > > But doing it here and now would lead to some conflicts with some other > > sysfs refactorings I'm doing. It will be part of a future series. > > --- > > kernel/bpf/sysfs_btf.c | 21 +++++---------------- > > 1 file changed, 5 insertions(+), 16 deletions(-) > > > > Nice, let's simplify. But why change the name to generic "vmlinux" if > it's actually btf_vmlinux? Can we keep the original btf-specific name? The file in sysfs is named "vmlinux", /sys/kernel/btf/vmlinux. This is what needs to be passed to the macro, it will name both the variable and the file after it. One alternative would be to use __BIN_ATTR_SIMPLE_RO() which allows a custom name. > > pw-bot: cr > > > diff --git a/kernel/bpf/sysfs_btf.c b/kernel/bpf/sysfs_btf.c > > index fedb54c94cdb830a4890d33677dcc5a6e236c13f..a24381f933d0b80b11116d05463c35e9fa66acb1 100644 > > --- a/kernel/bpf/sysfs_btf.c > > +++ b/kernel/bpf/sysfs_btf.c > > @@ -12,34 +12,23 @@ > > extern char __start_BTF[]; > > extern char __stop_BTF[]; > > > > -static ssize_t > > -btf_vmlinux_read(struct file *file, struct kobject *kobj, > > - struct bin_attribute *bin_attr, > > - char *buf, loff_t off, size_t len) > > -{ > > - memcpy(buf, __start_BTF + off, len); > > - return len; > > -} > > - > > -static struct bin_attribute bin_attr_btf_vmlinux __ro_after_init = { > > - .attr = { .name = "vmlinux", .mode = 0444, }, > > - .read = btf_vmlinux_read, > > -}; > > +static __ro_after_init BIN_ATTR_SIMPLE_RO(vmlinux); > > > > struct kobject *btf_kobj; > > > > static int __init btf_vmlinux_init(void) > > { > > - bin_attr_btf_vmlinux.size = __stop_BTF - __start_BTF; > > + bin_attr_vmlinux.private = __start_BTF; > > + bin_attr_vmlinux.size = __stop_BTF - __start_BTF; > > > > - if (bin_attr_btf_vmlinux.size == 0) > > + if (bin_attr_vmlinux.size == 0) > > return 0; > > > > btf_kobj = kobject_create_and_add("btf", kernel_kobj); > > if (!btf_kobj) > > return -ENOMEM; > > > > - return sysfs_create_bin_file(btf_kobj, &bin_attr_btf_vmlinux); > > + return sysfs_create_bin_file(btf_kobj, &bin_attr_vmlinux); > > } > > > > subsys_initcall(btf_vmlinux_init); > > > > --- > > base-commit: 28eb75e178d389d325f1666e422bc13bbbb9804c > > change-id: 20241122-sysfs-const-bin_attr-bpf-737286bb9f27 > > > > Best regards, > > -- > > Thomas Weißschuh > >