From nobody Wed Dec 17 09:14:55 2025 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 15C23C32772 for ; Tue, 23 Aug 2022 10:57:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1356686AbiHWK5i (ORCPT ); Tue, 23 Aug 2022 06:57:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50034 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348824AbiHWKxG (ORCPT ); Tue, 23 Aug 2022 06:53:06 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C85ECABF28; Tue, 23 Aug 2022 02:13:04 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 977CD61122; Tue, 23 Aug 2022 09:12:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9913BC433B5; Tue, 23 Aug 2022 09:12:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1661245979; bh=njHpn9+sds26FrtlsV8zBy8l/zR/7jGD2V8Z+PXK1VA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=1mEFLtTGl1sm3G3xUgng1sZnvQG79pwPYX8MgxUwgd34dSWLsG5hkpHqcUy5pg9Q8 zpxKtRW0GhTnsLqVQB/97RNEiTC2FdRMQIcETRCyAU8rAwqCQKdIeawhn+YxwZzlTY bxsVjt9ijDhZc8VFtkmtrb3LNJUNRLM3ykTwbFeA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Guenter Roeck , Michael Ellerman Subject: [PATCH 4.19 251/287] powerpc/pci: Fix get_phb_number() locking Date: Tue, 23 Aug 2022 10:27:00 +0200 Message-Id: <20220823080109.655210908@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220823080100.268827165@linuxfoundation.org> References: <20220823080100.268827165@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Michael Ellerman commit 8d48562a2729742f767b0fdd994d6b2a56a49c63 upstream. The recent change to get_phb_number() causes a DEBUG_ATOMIC_SLEEP warning on some systems: BUG: sleeping function called from invalid context at kernel/locking/mute= x.c:580 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 1, name: swapper preempt_count: 1, expected: 0 RCU nest depth: 0, expected: 0 1 lock held by swapper/1: #0: c157efb0 (hose_spinlock){+.+.}-{2:2}, at: pcibios_alloc_controller+0= x64/0x220 Preemption disabled at: [<00000000>] 0x0 CPU: 0 PID: 1 Comm: swapper Not tainted 5.19.0-yocto-standard+ #1 Call Trace: [d101dc90] [c073b264] dump_stack_lvl+0x50/0x8c (unreliable) [d101dcb0] [c0093b70] __might_resched+0x258/0x2a8 [d101dcd0] [c0d3e634] __mutex_lock+0x6c/0x6ec [d101dd50] [c0a84174] of_alias_get_id+0x50/0xf4 [d101dd80] [c002ec78] pcibios_alloc_controller+0x1b8/0x220 [d101ddd0] [c140c9dc] pmac_pci_init+0x198/0x784 [d101de50] [c140852c] discover_phbs+0x30/0x4c [d101de60] [c0007fd4] do_one_initcall+0x94/0x344 [d101ded0] [c1403b40] kernel_init_freeable+0x1a8/0x22c [d101df10] [c00086e0] kernel_init+0x34/0x160 [d101df30] [c001b334] ret_from_kernel_thread+0x5c/0x64 This is because pcibios_alloc_controller() holds hose_spinlock but of_alias_get_id() takes of_mutex which can sleep. The hose_spinlock protects the phb_bitmap, and also the hose_list, but it doesn't need to be held while get_phb_number() calls the OF routines, because those are only looking up information in the device tree. So fix it by having get_phb_number() take the hose_spinlock itself, only where required, and then dropping the lock before returning. pcibios_alloc_controller() then needs to take the lock again before the list_add() but that's safe, the order of the list is not important. Fixes: 0fe1e96fef0a ("powerpc/pci: Prefer PCI domain assignment via DT 'lin= ux,pci-domain' and alias") Reported-by: Guenter Roeck Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220815065550.1303620-1-mpe@ellerman.id.au Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/kernel/pci-common.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) --- a/arch/powerpc/kernel/pci-common.c +++ b/arch/powerpc/kernel/pci-common.c @@ -75,10 +75,6 @@ const struct dma_map_ops *get_pci_dma_op } EXPORT_SYMBOL(get_pci_dma_ops); =20 -/* - * This function should run under locking protection, specifically - * hose_spinlock. - */ static int get_phb_number(struct device_node *dn) { int ret, phb_id =3D -1; @@ -115,15 +111,20 @@ static int get_phb_number(struct device_ if (!ret) phb_id =3D (int)(prop & (MAX_PHBS - 1)); =20 + spin_lock(&hose_spinlock); + /* We need to be sure to not use the same PHB number twice. */ if ((phb_id >=3D 0) && !test_and_set_bit(phb_id, phb_bitmap)) - return phb_id; + goto out_unlock; =20 /* If everything fails then fallback to dynamic PHB numbering. */ phb_id =3D find_first_zero_bit(phb_bitmap, MAX_PHBS); BUG_ON(phb_id >=3D MAX_PHBS); set_bit(phb_id, phb_bitmap); =20 +out_unlock: + spin_unlock(&hose_spinlock); + return phb_id; } =20 @@ -134,10 +135,13 @@ struct pci_controller *pcibios_alloc_con phb =3D zalloc_maybe_bootmem(sizeof(struct pci_controller), GFP_KERNEL); if (phb =3D=3D NULL) return NULL; - spin_lock(&hose_spinlock); + phb->global_number =3D get_phb_number(dev); + + spin_lock(&hose_spinlock); list_add_tail(&phb->list_node, &hose_list); spin_unlock(&hose_spinlock); + phb->dn =3D dev; phb->is_dynamic =3D slab_is_available(); #ifdef CONFIG_PPC64