From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 661CB4014A7 for ; Mon, 2 Mar 2026 15:11:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772464304; cv=none; b=fE7lT2S6XyCvn49auVEF0aeF+LweA+ifmSbZzFZaxTklKzojUcrWlLc9h277o39m0W+9SOUG7urYXv8dgvjeFxHuLU6NsaHBQjaEjUMYNOnheccZKrZDSN88rjsTdN6/cJ5VfVKMpam4orlrler8Uz/0ThguV3vW/IqxFFExWTM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772464304; c=relaxed/simple; bh=pqQAGan4yvTVrFiL32CHCgoQyF1G89388WDkZh9066g=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=bY8/Aurgc1dK2oVKg95cWZSep1W/oWLXe2EJFeFwmN461mFnG02jaLP46sDKS8/PS7azo1dj9bIleTwmp1HrZIyuB3E6FpvjFG7J8DGTTCXgtrfk/yEgXNbYabr9pDbUWErdkXspJIJt+TFNQKn19jnWh6lGIe72/ytMDnpX1/g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=fo1OTfAl; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b=T4EVGc1S; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="fo1OTfAl"; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b="T4EVGc1S" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1772464302; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=fR0fvLxS9OT19o4gHC8nFDyqzxeV7tuHCO9Mj5KxIFo=; b=fo1OTfAlN9wX6vDkD9lDdQUnKGiHEi12WZaQ/Ed1oMn76Dx8lXBbKTWSl/EgEPQCRUqOYD Q1xkhQAPrYXFyJ5PBKTYadFP3CCN1K03cWEinAThOB9WUn/YTp42Yx9XWQq170wf30J6PP Irc5EqHtfMid4Bv9/dzI61q35AFf7Ug= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-313-Kda5trwqNNO-_swJ0y3nhQ-1; Mon, 02 Mar 2026 10:11:41 -0500 X-MC-Unique: Kda5trwqNNO-_swJ0y3nhQ-1 X-Mimecast-MFC-AGG-ID: Kda5trwqNNO-_swJ0y3nhQ_1772464300 Received: by mail-wm1-f69.google.com with SMTP id 5b1f17b1804b1-4837c597cd5so27476045e9.3 for ; Mon, 02 Mar 2026 07:11:40 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1772464300; x=1773069100; 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=fR0fvLxS9OT19o4gHC8nFDyqzxeV7tuHCO9Mj5KxIFo=; b=T4EVGc1S3KDxLR9wb870gWHgh7Ib8ee7cdBmFLELZXC0mqEd66GAkEMD/1vYSzgppE zwNnis61nntKhzs/3qhE3U15fQ3iAGkG4N74yKaIjznBI1MitsTNKBklCIJ8KpiITu9Y 6YKkRiOJuSiC+7ona9hnRWacuHf0SrdaDi8adN4tmKA+2qdL9SkY+fpiWnpuENLrgj43 heDrX54xhP3p7UFQ2E7RzPiIVea02PCMKAgk+45xpajpbFj7d/p6OvgYoXXZAQuEL4be WuidYCwC7ev+lNF5tA76OA2AhmuIvP9hi5m6F5DPekBj48LBocziPz3maSafq5FDXqIp RgOw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1772464300; x=1773069100; h=mime-version:user-agent:content-transfer-encoding:autocrypt :references:in-reply-to:date:cc:to:from:subject:message-id:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=fR0fvLxS9OT19o4gHC8nFDyqzxeV7tuHCO9Mj5KxIFo=; b=jwPH0duyOwAs9r86PoyT1JVIXNLmjlikIkANdFD3ut5fqZk9cCWYlB2CenOcefjGP5 cEdowQTkG59KVr4YEbLs7cf9c6MoB3J0pyfD36nDt2S0k2MqXpDOiTSWw0oNvDCV7M8I 1hV4rMxwkgzh5UwgnL0ZbcUi/EOhDNvzHcZaMLOv/rXmJH4JJhk3yPYTXl47ak3W+Tec BuyVTYgON4HSO4OhCxyy1Ggks1d6kQPwbmWc0Lrzsui/26esz7n/Cy/lsWDrHyUY+nBA awPLhhcBk9a7MoYY4kpMioXkVM0wIpC7J3eDWeCmc6w3+F1bRyYpG8uJKNBzbrGKvXV0 QQhg== X-Gm-Message-State: AOJu0YxxDGeHKVIQ+VtOVjBxd+tq5DFH+ixnyx3UXSm5msE3JpDiJ56I UhoyCIDIFMZMp7wVCjdJfZezL5IDue8CrPVDTg0p5uigHt2XZo1Si3FEAj+mtOF0Dp6ty8ViDjc Z4Sz9huoRZbh0U1O8uVY2C0HJK1f4g20FE+BFiBzS0QYddDs9KERZvObGw1fcXkFd8w== X-Gm-Gg: ATEYQzxGHuyN7NhXQWTM5gxvgz8OcnNpOBMPVOmZ4eld1kTReFdWfI1h4MoxpbunOo/ 6KUYfCMcx7er/rno54t6pkDVs4c7bIV61RJ9L1aQgglFJY71JSgecIWTfkZesZDYk+CE6qu2LxM QV21c/5sTReP4eP7simeuaEaE9WJRDc+/PHqCPSA/VRNeV3QUGVWscVSEud09kiv8HENwGjzc/4 PJwtV+/iDVGipva/SCNtDci5H0rbE7meEfEK6reXIR8Km7yGpKNVQiC6AESKM3/uHBMBm06jYqT QEPweLmrxPNDCm4aFp8ivvqAaVU6tIHKCsXhtOZM10IleSVUFWjfDTup4OD8ir/YnAhFMrvZs9t VuRB5fNXfqWIcrl3z7tCmYM8Ve0JF9IUBR3zdizSPNtCLuFl6L3bxp0S7zpT6QjVNe5QnR2A5f6 20Wv14zJ0Ehv9qJkQ= X-Received: by 2002:a05:600c:c059:20b0:483:709e:f239 with SMTP id 5b1f17b1804b1-483c9beacf1mr153607045e9.22.1772464299854; Mon, 02 Mar 2026 07:11:39 -0800 (PST) X-Received: by 2002:a05:600c:c059:20b0:483:709e:f239 with SMTP id 5b1f17b1804b1-483c9beacf1mr153606585e9.22.1772464299371; Mon, 02 Mar 2026 07:11:39 -0800 (PST) Received: from gmonaco-thinkpadt14gen3.rmtit.csb (212-8-243-115.hosted-by-worldstream.net. [212.8.243.115]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-483c3b770c2sm281641905e9.10.2026.03.02.07.11.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Mar 2026 07:11:38 -0800 (PST) Message-ID: <4369c322cd0626844ace0f42c55ec2cd9890cda0.camel@redhat.com> Subject: Re: [PATCH v6 15/16] rv: Add deadline monitors From: Gabriele Monaco To: Juri Lelli Cc: linux-kernel@vger.kernel.org, Steven Rostedt , Nam Cao , Juri Lelli , Jonathan Corbet , Masami Hiramatsu , linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, Peter Zijlstra , Tomas Glozar , Clark Williams , John Kacur Date: Mon, 02 Mar 2026 16:11:36 +0100 In-Reply-To: References: <20260225095122.80683-1-gmonaco@redhat.com> <20260225095122.80683-16-gmonaco@redhat.com> Autocrypt: addr=gmonaco@redhat.com; prefer-encrypt=mutual; keydata=mDMEZuK5YxYJKwYBBAHaRw8BAQdAmJ3dM9Sz6/Hodu33Qrf8QH2bNeNbOikqYtxWFLVm0 1a0JEdhYnJpZWxlIE1vbmFjbyA8Z21vbmFjb0BrZXJuZWwub3JnPoiZBBMWCgBBFiEEysoR+AuB3R Zwp6j270psSVh4TfIFAmjKX2MCGwMFCQWjmoAFCwkIBwICIgIGFQoJCAsCBBYCAwECHgcCF4AACgk Q70psSVh4TfIQuAD+JulczTN6l7oJjyroySU55Fbjdvo52xiYYlMjPG7dCTsBAMFI7dSL5zg98I+8 cXY1J7kyNsY6/dcipqBM4RMaxXsOtCRHYWJyaWVsZSBNb25hY28gPGdtb25hY29AcmVkaGF0LmNvb T6InAQTFgoARAIbAwUJBaOagAULCQgHAgIiAgYVCgkICwIEFgIDAQIeBwIXgBYhBMrKEfgLgd0WcK eo9u9KbElYeE3yBQJoymCyAhkBAAoJEO9KbElYeE3yjX4BAJ/ETNnlHn8OjZPT77xGmal9kbT1bC1 7DfrYVISWV2Y1AP9HdAMhWNAvtCtN2S1beYjNybuK6IzWYcFfeOV+OBWRDQ== Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.58.3 (3.58.3-1.fc43) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Mon, 2026-03-02 at 15:37 +0100, Juri Lelli wrote: > > + if (!pid) > > + *p =3D current; > > + else { > > + /* > > + * Required for find_task_by_vpid, make sure the caller > > doesn't > > + * need to get_task_struct(). > > + */ > > + guard(rcu)(); > > + *p =3D find_task_by_vpid(pid); > > + if (unlikely(!*p)) > > + return -EINVAL; > > + } >=20 > Not sure I get this comment. RCU is released when the function returns, > but then the task pointer is dereferenced by callers? The idea was that the caller should ensure there's no need to do get_task_struct() (which is fine within the syscall, I'm assuming). But looking at it again, that's not even necessary as long as the caller lo= cked RCU, which they should do instead of guarding here. So yeah, the comment is misleading and I should just do: guard(rcu)(); extract_params(...); Thanks for the observation, Gabriele