From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (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 7FFE225C81F; Fri, 27 Jun 2025 08:45:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.163.158.5 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751013916; cv=none; b=nGC5AaoKiBI1lv7zdzbxVSjp1Zlf40PdyBnzOryahW2NnggUIA6NfrU1TJWD7CAozKvmVtmQOJZyc2/N5cxShPhoCv2XFVsPokD1dOJzHthrVInwzqT2B6osDUOuXQivLItPLIpFcAIBQ0R6+KPO5T0Y4QrAsLdgi+UFyWTLrP8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751013916; c=relaxed/simple; bh=8w5TeuyPxlptFjUY6ArFjdkAPl+REWCj4tvTr+seV7o=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ON4K1MpgAWNmUCPrfVh4yWo027dExlDLE1rmGMlzSlJDzHPDhAqHkQK1HUHsWnRsgfok4M6Tx7lSZLr/uDz/R4EO0j9YnHWA7FWRL4ACt2PNE3/N70B2RhgxvvZQdVzUimz0yKrxsHfDVTqtQgmOF7ftzcgVKZ+qBL0neMs6QYQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=de.ibm.com; spf=pass smtp.mailfrom=de.ibm.com; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b=PLfnY8P3; arc=none smtp.client-ip=148.163.158.5 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=de.ibm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=de.ibm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b="PLfnY8P3" Received: from pps.filterd (m0356516.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.2/8.18.1.2) with ESMTP id 55QMWGsp031577; Fri, 27 Jun 2025 08:45:12 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=pp1; bh=fN8e7t +1zr8+1WCchHeHmB33VLUmUSL2gWn8n+v4ZwM=; b=PLfnY8P3CTO8+u0sBkpsmN bz06r0RYT3xKFRGX0Oize/oQkRn246TvocnNCyctAHOU7ZVWsCQ/BUJf9l9VaaYD dTtVML8//DwIOabmp3bRwKQm5mLOHLV+1ft9Oc/6i06LshDlJJWRVkFopI51dOYe DhWTrSrnUajK561opa9CdlvQXflKzo7KnpDbrLgO11Fr34oGBy1Iz19X9rz17NDo dhcWGbZpr1KDkfIIbHjeR9RalqQkB+UOxNdrc6G89cr2qBECL4voC59KeKKupDp1 CiJUiusCiQIZaF8Yvo5ITBhm+5DkH0WDt2WdDk4lCeU1fA2r08cy+legI/2pKerQ == Received: from ppma12.dal12v.mail.ibm.com (dc.9e.1632.ip4.static.sl-reverse.com [50.22.158.220]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 47dj5uc23h-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 27 Jun 2025 08:45:11 +0000 (GMT) Received: from pps.filterd (ppma12.dal12v.mail.ibm.com [127.0.0.1]) by ppma12.dal12v.mail.ibm.com (8.18.1.2/8.18.1.2) with ESMTP id 55R81lYO014987; Fri, 27 Jun 2025 08:45:10 GMT Received: from smtprelay01.fra02v.mail.ibm.com ([9.218.2.227]) by ppma12.dal12v.mail.ibm.com (PPS) with ESMTPS id 47e72u3f5u-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 27 Jun 2025 08:45:10 +0000 Received: from smtpav05.fra02v.mail.ibm.com (smtpav05.fra02v.mail.ibm.com [10.20.54.104]) by smtprelay01.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 55R8j6U458786234 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 27 Jun 2025 08:45:07 GMT Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id DB5822004D; Fri, 27 Jun 2025 08:45:06 +0000 (GMT) Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 3355E20043; Fri, 27 Jun 2025 08:45:06 +0000 (GMT) Received: from [9.111.32.43] (unknown [9.111.32.43]) by smtpav05.fra02v.mail.ibm.com (Postfix) with ESMTP; Fri, 27 Jun 2025 08:45:06 +0000 (GMT) Message-ID: Date: Fri, 27 Jun 2025 10:45:05 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 2/5] KVM: s390: remove unneeded srcu lock To: Nina Schoetterl-Glausch , Claudio Imbrenda , linux-kernel@vger.kernel.org Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org, frankja@linux.ibm.com, seiden@linux.ibm.com, nrb@linux.ibm.com, david@redhat.com, hca@linux.ibm.com, agordeev@linux.ibm.com, svens@linux.ibm.com, gor@linux.ibm.com References: <20250514163855.124471-1-imbrenda@linux.ibm.com> <20250514163855.124471-3-imbrenda@linux.ibm.com> <8373c4a476e6a8f714a559d0fad8f3fed66089f1.camel@linux.ibm.com> <0b90cd0ad24727c9d7b110f09fd79b2525b4fbe1.camel@linux.ibm.com> Content-Language: en-US From: Christian Borntraeger In-Reply-To: <0b90cd0ad24727c9d7b110f09fd79b2525b4fbe1.camel@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: GlP2qVrpn1eigaspF6t0UFwcJnru7XY_ X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwNjI3MDA2NiBTYWx0ZWRfXys4I6R2dq0fP +t0MSeD4Rqlp6ZkQ9JscAnrYVxuspA6H5PzYnCfsUa5SHuT7bSKihMzCvN6f1zNUyrnVfjbZgWJ UPailssoTf3pdwrgkkX7wzpcN3noc5e/4PjIcoUS/FlLAPDyaTDCE+y/WegkqCVz74TYkisim9b XNvB9GM4Z63wtDpwXKyIp8ezOm52n1bBUNKh4uEnGtokVLxopvkpNN1Exe6MyUennVPPP9ZrtSI B/ZasfFIX8at9UITA1Rf8l6+cs+2PEMiiPAgf08ADhnzKVP2SdjOBdpXbRo7xoRQnBzNvfN/hz1 iVr4Ef/MtEC4gufJeOoT/KoGSZrFUEF7hHosXmTFSOdRQPMA9hJ57zRH9mU9KrLI4wWfT4KaUuH 6HFSQnNmKE6R9Mz4zk8i6dwg0lWyGE6zleRDwR0GHGc65VzM5J5Yvxdnzti1oKPI8NupZRUz X-Authority-Analysis: v=2.4 cv=MshS63ae c=1 sm=1 tr=0 ts=685e5a17 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=IkcTkHD0fZMA:10 a=6IFa9wvqVegA:10 a=VnNF1IyMAAAA:8 a=zO_5yEawC278s_0qgMcA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: GlP2qVrpn1eigaspF6t0UFwcJnru7XY_ X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.1.7,FMLib:17.12.80.40 definitions=2025-06-27_03,2025-06-26_05,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 bulkscore=0 lowpriorityscore=0 spamscore=0 mlxlogscore=618 impostorscore=0 clxscore=1015 phishscore=0 malwarescore=0 suspectscore=0 adultscore=0 priorityscore=1501 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2505280000 definitions=main-2506270066 Am 20.05.25 um 16:34 schrieb Nina Schoetterl-Glausch: > On Mon, 2025-05-19 at 16:42 +0200, Nina Schoetterl-Glausch wrote: >> On Wed, 2025-05-14 at 18:38 +0200, Claudio Imbrenda wrote: >>> All paths leading to handle_essa() already hold the kvm->srcu. >>> Remove unneeded srcu locking from handle_essa(). >>> >>> Signed-off-by: Claudio Imbrenda >> >> Reviewed-by: Nina Schoetterl-Glausch >> >> Why are you removing it tho? >> It should be very low cost and it makes the code more robust, >> since handle_essa itself ensures that it has the lock. >> It is also easier to understand which synchronization the function does. >> You could of course add a comment stating that the kvm srcu read side needs >> to be held. I think this would be good to have if you really don't want the >> srcu_read_lock here. >> But then you might also want that documented up the call chain. > > Actually, can we use __must_hold or have some assert? Yes, that might be the best way.