From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f54.google.com (mail-wm1-f54.google.com [209.85.128.54]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EDC2717C9 for ; Fri, 19 Jan 2024 00:46:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.54 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705625205; cv=none; b=Gr8mM7pgiRYliBbPsGJxO3FrZYAMuNKsE1xnCvYibyo4Ms6bsNP+ZeDJ+CY4tEUnRmCRahoQWQjozglIxj8sM8nRg5ns4/s6FcBHRA/PJLTgNDYIaXZv43jTjEcrmTRJFyQF+IQy4pQU+mOcSlAwOqjyxePBNhLrBkb/JOxKqAY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705625205; c=relaxed/simple; bh=PCenqpN2ZyWWyODzpvxnOXNBQL8XKDSeaB2tEqXiBzI=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=DvKx5gbupysk2yQ4FzMF4l0HUIk1nYBmBCFlUFGM6nEyG/6JL3umkgpuQ2Gpp3abQRwKOh5rdONv7PyaVpmtZAexvlXHrlXz7S+fPJCgva0ez8T82Q+x4ZepdmrP65+9KNiLSNPUEty5cT6xHR7dVDZsRBRg1nHARyf4IcdOGmI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=GpjirHne; arc=none smtp.client-ip=209.85.128.54 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="GpjirHne" Received: by mail-wm1-f54.google.com with SMTP id 5b1f17b1804b1-40e60e137aaso2712895e9.0 for ; Thu, 18 Jan 2024 16:46:43 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1705625202; x=1706230002; darn=vger.kernel.org; h=mime-version:user-agent:content-transfer-encoding:autocrypt :references:in-reply-to:date:cc:to:from:subject:message-id:from:to :cc:subject:date:message-id:reply-to; bh=90x6wo5Llald8frT9AQnLRmsYFuZC093bkRIgp5TokY=; b=GpjirHnecQ+J8//6GTvCB1+dbshGviNaq9jRX7hvzi3Ko3Bgicorm+Ib5xdFnxLDFE UNMg3EZCSWlZ96stkH8neeiHQPHxUVmR64xmeeBBL2PYGVH9YHMOCrpo7C0aCKGdqK0B B7+6osdILknQuun01aHcuHemxinpGbrOQ+zqRpqX4nlPMLEDDOhsoJ3k4qGwTMvaVXfy jDSMq2YHKvR8sMY6X29uDgNaSKz1kqqNBBSzQccr2dNmRqEJKVVMnvP/RlRp2xj3wDmD lycHYcvcaAeolue6QVbotE+X8tcp2J1P40PcwRYfpakLqfxQ5LCm+h/ccrHCw0efSPK2 mQ6Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1705625202; x=1706230002; h=mime-version:user-agent:content-transfer-encoding:autocrypt :references:in-reply-to:date:cc:to:from:subject:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=90x6wo5Llald8frT9AQnLRmsYFuZC093bkRIgp5TokY=; b=p8y9GItj1SKBB/Qx3uopGQWx7uVTG+9hnlZmRVcxYOsJV5k+1nKcRrqFmA3gmVwL6k yHKbhv4DuAuoLjZGebvEM+2vvD9IXu914/HMnql27IpQd0D+DYSNbUewab62XSMC+vB4 Q8ZTzxAEWBMHthAnUKYk4cNWo/55/PJ9BtxN8p5taZzlLsrozo1uo0eM7I4+2M8Fw1fI qkaFRz69tkmMGDnlv9GPWg46WsAZ8sJoaZlPjVa6Y8hGYMdxJ/y2z/sFzcz5HWZiBBul KO6oKIvYQyJ712Plq993w/sYR5TYJPS6arX2yVy/SMzi/Hvb61zVYArJ6+vsWA6WrV41 R1/w== X-Gm-Message-State: AOJu0YwVgeXBBp93nsG0FS7Hjmha1zZOY8MnV2h1K65tQ8fDw0RfeDBs aUDTdTndL7IcZYZ15fZGypkkg9Xy7ofpQWWeOHsfzOWKTAg3iKfl5Gk8s/GO X-Google-Smtp-Source: AGHT+IHd9m7pdpONTjhm8GrZB5TQj6pPJxkaAhXyC8ucYLZiBli+2EaboRy/4yu9WJJtmKsK5w2kLw== X-Received: by 2002:a05:600c:4213:b0:40d:30fe:a7d with SMTP id x19-20020a05600c421300b0040d30fe0a7dmr1039491wmh.109.1705625201926; Thu, 18 Jan 2024 16:46:41 -0800 (PST) Received: from [192.168.1.95] (host-176-36-0-241.b024.la.net.ua. [176.36.0.241]) by smtp.gmail.com with ESMTPSA id az4-20020a05600c600400b0040e9d281230sm468614wmb.30.2024.01.18.16.46.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 18 Jan 2024 16:46:41 -0800 (PST) Message-ID: Subject: Re: [PATCH v2 bpf 1/5] libbpf: feature-detect arg:ctx tag support in kernel From: Eduard Zingerman To: Andrii Nakryiko Cc: Andrii Nakryiko , bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net, martin.lau@kernel.org, kernel-team@meta.com Date: Fri, 19 Jan 2024 02:46:40 +0200 In-Reply-To: References: <20240117223340.1733595-1-andrii@kernel.org> <20240117223340.1733595-2-andrii@kernel.org> <3cb503acbd2d65dc08172d620fe5dfff5f51be0d.camel@gmail.com> Autocrypt: addr=eddyz87@gmail.com; prefer-encrypt=mutual; keydata=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 nYzhLWGcczc6J71q1Dje0l5vIPaSFOgwmWD4DA+WvuxM/shH4rtWeodbv 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 t1iq+gsfnXbPz5AnS598ScZI1oP7OrPSFJkt/z4acEbOQDQs8aUqrd46PV jsdqGvKnXZxzylux29UTNby4jTlz9pNJM+wPrDRmGfchLDUmf6CffaUYCbu4FiId+9+dcTCDvxbABRy1C3OJ8QY7cxfJ+pEZW18fRJ0XCl/fiV/ecAOfB3HsqgTzAn555h0rkFgay0hAvMU/mAW/CFNSIxV397zm749ZNLA0L2dMy1AKuOqH+/B+/ImBfJMDjmdyJQ8WU/OFRuGLdqOd2oZrA1iuPIa+yUYyZkaZfz/emQwpIL1+Q4p1R/OplA4yc301AqruXXUcVDbEB+joHW3hy5FwK5t5OwTKatrSJBkydSF9zdXy98fYzGniRyRA65P0Ix/8J3BYB4edY2/w0Ip/mdYsYQljBY0A== Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.50.3 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Thu, 2024-01-18 at 16:43 -0800, Andrii Nakryiko wrote: > On Thu, Jan 18, 2024 at 11:50=E2=80=AFAM Eduard Zingerman wrote: [...] > > Question: > > suppose this is an old kernel and decl tags are not supported, > > should negative result be cached as 0 in such case? >=20 > yep, it should, and it will be eventually when > probe_kern_arg_ctx_tag() will be plugged back into kernel_supports() > framework. For now this small inefficiency seems fine, given it's > temporary. Understood, thank you.