[{"id":3679866,"web_url":"http://patchwork.ozlabs.org/comment/3679866/","msgid":"<20260421124800.GC2707369@p1gen4-pw042f0m>","list_archive_url":null,"date":"2026-04-21T12:48:00","subject":"Re: [PATCH v13 1/2] PCI/IOV: Make pci_lock_rescan_remove() reentrant\n and protect sriov_add_vfs/sriov_del_vfs","submitter":{"id":91674,"url":"http://patchwork.ozlabs.org/api/people/91674/","name":"Benjamin Block","email":"bblock@linux.ibm.com"},"content":"On Tue, Apr 21, 2026 at 10:34:20AM +0300, Ionut Nechita (Wind River) wrote:\n> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c\n> index b63cd0c310bc..0e62081bc5e5 100644\n> --- a/drivers/pci/probe.c\n> +++ b/drivers/pci/probe.c\n> @@ -3513,16 +3513,30 @@ EXPORT_SYMBOL_GPL(pci_rescan_bus);\n> * routines should always be executed under this mutex.\n> */\n> DEFINE_MUTEX(pci_rescan_remove_lock);\n> +static struct task_struct *pci_rescan_remove_owner;\n\nYou could make this variable `const`:\n\n static const struct task_struct *pci_rescan_remove_owner;\n\nso it is clear that this pointer is not meant to be used to modify the\ntask_struct in any way - just for these comparisons.\n\n> +static unsigned int pci_rescan_remove_depth;\n> \n> void pci_lock_rescan_remove(void)\n> {\n> -\tmutex_lock(&pci_rescan_remove_lock);\n> +\tif (pci_rescan_remove_owner == current) {\n> +\t\tpci_rescan_remove_depth++;\n> +\t} else {\n> +\t\tmutex_lock(&pci_rescan_remove_lock);\n> +\t\tpci_rescan_remove_owner = current;\n> +\t\tpci_rescan_remove_depth = 1;\n> +\t}\n> }\n> EXPORT_SYMBOL_GPL(pci_lock_rescan_remove);\n> \n> void pci_unlock_rescan_remove(void)\n> {\n> -\tmutex_unlock(&pci_rescan_remove_lock);\n> +\tif (WARN_ON(pci_rescan_remove_owner != current))\n> +\t\treturn;\n> +\n> +\tif (--pci_rescan_remove_depth == 0) {\n> +\t\tpci_rescan_remove_owner = NULL;\n> +\t\tmutex_unlock(&pci_rescan_remove_lock);\n> +\t}\n> }\n> EXPORT_SYMBOL_GPL(pci_unlock_rescan_remove);\n\n\nBut anyway, with, or without this change, this looks good to me. I hadn't run\ninto any linker issues, but I only ever used our debug config.\nAlso holds up with my tests on my s390 rig.\n\n\nReviewed-by: Benjamin Block \nTested-by: Benjamin Block ","headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-pci@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=ibm.com header.i=@ibm.com header.a=rsa-sha256\n header.s=pp1 header.b=TWIG9w6n;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=172.232.135.74; helo=sto.lore.kernel.org;\n envelope-from=linux-pci+bounces-52833-incoming=patchwork.ozlabs.org@vger.kernel.org;\n receiver=patchwork.ozlabs.org)","smtp.subspace.kernel.org;\n\tdkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com\n header.b=\"TWIG9w6n\"","smtp.subspace.kernel.org;\n arc=none smtp.client-ip=148.163.156.1","smtp.subspace.kernel.org;\n dmarc=pass (p=none dis=none) header.from=linux.ibm.com","smtp.subspace.kernel.org;\n spf=pass smtp.mailfrom=linux.ibm.com"],"Received":["from sto.lore.kernel.org (sto.lore.kernel.org [172.232.135.74])\n\t(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n\t key-exchange x25519)\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4g0Mbt0mLvz1yGt\n\tfor ; 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