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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id BED8EC43458 for ; Wed, 1 Jul 2026 13:52:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:content-type: Content-Transfer-Encoding:MIME-Version:References:In-Reply-To:Message-ID:Date :Subject:Cc:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=f+nFPAVBpWgUR1X36PZ/lmagU7XjSBga3RsLirYRi04=; b=OTQs1lZENIWc5q7eWF0iGgmxi0 ONgFDEMT3MSzzcJmFCoRu0lUSnKF9gCmTFxQw3uyl22mPk5Gd7bxG75haApOn2+VuJxaNq8qn1Mba 3o791R7Pt1EGaekxoAUv14bn5Mrao/ZayFTNrSBeN6rL8X0gEmNbph5uM5vTWnzlsIPQZIrX6Wpnt /u07jSYrS1MZMSV/BzvUFWt8tDN7rvCXHTvPA3AARuG5pdgjq7Pj07jyLylBDjzuJFm1Rh7PbVsA1 1P1Jmmg08gCBAztmFGbRxaN9lyLTOKCu1TOV3u9kgbuTTK4ua8FZbK6QKZSccyn/Ze8m6/LjNcaGi uADYhuLQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wevMR-00000002DaK-3sG0; Wed, 01 Jul 2026 13:52:19 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wevMJ-00000002DYl-0L8k for kexec@lists.infradead.org; Wed, 01 Jul 2026 13:52:12 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1782913930; 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; bh=f+nFPAVBpWgUR1X36PZ/lmagU7XjSBga3RsLirYRi04=; b=Xg77fI3AGkv1M6DzLJi0O+xfuCDu03iYZRN0Nghzy0vVYgMOcV2cBO/ooD4uOVb+ajD+XZ dGS8jCOOwgnvpHRDnL3CSRyttIYFWRG6VbBd8XwTzFUy9xBd09rOXqAxugeg1eKZZSOWcC s2YMBg9k4b8mF+2SzyiCiKj62P4ljqk= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-433-6fJfttuPNbS7DCGx_AGIJA-1; Wed, 01 Jul 2026 09:50:43 -0400 X-MC-Unique: 6fJfttuPNbS7DCGx_AGIJA-1 X-Mimecast-MFC-AGG-ID: 6fJfttuPNbS7DCGx_AGIJA_1782913840 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 8D2CC1944B24; Wed, 1 Jul 2026 13:50:39 +0000 (UTC) Received: from djeffery-thinkpadp1gen3.rmtusga.csb (unknown [10.22.81.69]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 72107180076D; Wed, 1 Jul 2026 13:50:35 +0000 (UTC) From: David Jeffery To: driver-core@lists.linux.dev, Greg Kroah-Hartman , "Rafael J. Wysocki" , Danilo Krummrich Cc: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-scsi@vger.kernel.org, Tarun Sahu , Pasha Tatashin , =?UTF-8?q?Micha=C5=82=20C=C5=82api=C5=84ski?= , Jordan Richards , Ewan Milne , John Meneghini , "Lombardi, Maurizio" , Stuart Hayes , Laurence Oberman , Bart Van Assche , Bjorn Helgaas , "Martin K . Petersen" , John Garry , kexec@lists.infradead.org, David Jeffery Subject: [PATCH 2/5] driver core: do not always lock parent in shutdown Date: Wed, 1 Jul 2026 09:50:12 -0400 Message-ID: <20260701135015.81937-3-djeffery@redhat.com> In-Reply-To: <20260701135015.81937-1-djeffery@redhat.com> References: <20260701135015.81937-1-djeffery@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 X-Mimecast-MFC-PROC-ID: UpL5X5ESEOWWulN18sDJhoFd0C6OGBzkR4kjbzNsT5c_1782913840 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260701_065211_208271_D45DD6FE X-CRM114-Status: GOOD ( 19.84 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org Don't lock a parent device unless it is needed in device_shutdown. This is in preparation for making device shutdown asynchronous, when it will be needed to allow children of a common parent to shut down simultaneously. And only acquire a reference to the parent device if the parent is to be locked. Signed-off-by: Stuart Hayes Signed-off-by: David Jeffery Tested-by: Laurence Oberman --- drivers/base/core.c | 42 ++++++++++++++++++++++++++---------------- 1 file changed, 26 insertions(+), 16 deletions(-) diff --git a/drivers/base/core.c b/drivers/base/core.c index 74c693cd19cf..3b3d983b1747 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -4865,14 +4865,10 @@ int device_change_owner(struct device *dev, kuid_t kuid, kgid_t kgid) return error; } -static void shutdown_one_device(struct device *dev) +static void __shutdown_one_device(struct device *dev) { - struct device *parent = dev->parent; - - /* hold lock to avoid race with probe/release */ - if (parent) - device_lock(parent); - device_lock(dev); + if (dev->p->dead) + return; /* Don't allow any more runtime suspends */ pm_runtime_get_noresume(dev); @@ -4892,12 +4888,32 @@ static void shutdown_one_device(struct device *dev) dev_info(dev, "shutdown\n"); dev->driver->shutdown(dev); } +} - device_unlock(dev); - if (parent) +static void shutdown_one_device(struct device *dev) +{ + struct device *parent; + + device_lock(dev); + + /* use parent lock if needed to avoid race with probe/release */ + if (dev->bus && dev->bus->need_parent_lock && !dev->p->dead && + (parent = get_device(dev->parent))) { + /* the parent lock needs to be acquired first, so re-lock */ + device_unlock(dev); + + device_lock(parent); + device_lock(dev); + + __shutdown_one_device(dev); + device_unlock(dev); device_unlock(parent); + put_device(parent); + } else { + __shutdown_one_device(dev); + device_unlock(dev); + } - put_device(parent); put_device(dev); } @@ -4923,12 +4939,6 @@ void device_shutdown(void) dev = list_entry(devices_kset->list.prev, struct device, kobj.entry); - /* - * hold reference count of device's parent to - * prevent it from being freed because parent's - * lock is to be held - */ - get_device(dev->parent); get_device(dev); /* * Make sure the device is off the kset list, in the -- 2.54.0