Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755598Ab1DGI04 (ORCPT ); Thu, 7 Apr 2011 04:26:56 -0400 Received: from va3ehsobe004.messaging.microsoft.com ([216.32.180.14]:12503 "EHLO VA3EHSOBE004.bigfish.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755262Ab1DGI0y (ORCPT ); Thu, 7 Apr 2011 04:26:54 -0400 X-SpamScore: -2 X-BigFish: VPS-2(zzbb2cKzz1202hzz8275bh8275dhz32i668h839h62h) X-Spam-TCS-SCL: 1:0 X-Forefront-Antispam-Report: KIP:(null);UIP:(null);IPVD:NLI;H:ausb3twp01.amd.com;RD:none;EFVD:NLI X-WSS-ID: 0LJ9WSH-01-95X-02 X-M-MSG: From: Joerg Roedel To: Greg Kroah-Hartman , Sarah Sharp , Andiry Xu CC: , , Joerg Roedel , Subject: [PATCH] USB host: Fix lockdep warning in AMD PLL quirk Date: Thu, 7 Apr 2011 10:26:29 +0200 Message-ID: <1302164789-31887-1-git-send-email-joerg.roedel@amd.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain X-OriginatorOrg: amd.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5080 Lines: 167 Booting 2.6.38 on my test machine produces a lockdep warning from the usb_amd_find_chipset_info() function: WARNING: at /data/lemmy/linux.trees.git/kernel/lockdep.c:2465 lockdep_trace_alloc+0x95/0xc2() Hardware name: Snook Modules linked in: Pid: 959, comm: work_for_cpu Not tainted 2.6.39-rc2+ #22 Call Trace: [] warn_slowpath_common+0x80/0x98 [] ? T.492+0x24/0x26 [] warn_slowpath_null+0x15/0x17 [] lockdep_trace_alloc+0x95/0xc2 [] slab_pre_alloc_hook+0x18/0x3b [] kmem_cache_alloc_trace+0x25/0xba [] T.492+0x24/0x26 [] pci_get_subsys+0x2e/0x73 sr0: scsi3-mmc drive: 48x/48x writer dvd-ram cd/rw xa/form2 cdda tray [] pci_get_device+0x11/0x13 [] usb_amd_find_chipset_info+0x3f/0x18a ... It turns out that this function calls pci_get_device under a spin_lock with irqs disabled, but the pci_get_device function is only allowed in preemptible context. This patch fixes this by using temporary variables in the quirk algorithm and commiting them later to the struct under the lock. This moves all pci_get_device() invocations out of the spin_lock and fixes the lockdep warning. Cc: stable@kernel.org Signed-off-by: Joerg Roedel --- drivers/usb/host/pci-quirks.c | 86 +++++++++++++++++++++++++---------------- 1 files changed, 52 insertions(+), 34 deletions(-) diff --git a/drivers/usb/host/pci-quirks.c b/drivers/usb/host/pci-quirks.c index 1d586d4..b5802f6 100644 --- a/drivers/usb/host/pci-quirks.c +++ b/drivers/usb/host/pci-quirks.c @@ -84,65 +84,83 @@ int usb_amd_find_chipset_info(void) { u8 rev = 0; unsigned long flags; + struct amd_chipset_info info; + int ret; spin_lock_irqsave(&amd_lock, flags); - amd_chipset.probe_count++; /* probe only once */ - if (amd_chipset.probe_count > 1) { + if (amd_chipset.probe_count > 0) { spin_unlock_irqrestore(&amd_lock, flags); return amd_chipset.probe_result; } + info = amd_chipset; + spin_unlock_irqrestore(&amd_lock, flags); - amd_chipset.smbus_dev = pci_get_device(PCI_VENDOR_ID_ATI, 0x4385, NULL); - if (amd_chipset.smbus_dev) { - rev = amd_chipset.smbus_dev->revision; + info.smbus_dev = pci_get_device(PCI_VENDOR_ID_ATI, 0x4385, NULL); + if (info.smbus_dev) { + rev = info.smbus_dev->revision; if (rev >= 0x40) - amd_chipset.sb_type = 1; + info.sb_type = 1; else if (rev >= 0x30 && rev <= 0x3b) - amd_chipset.sb_type = 3; + info.sb_type = 3; } else { - amd_chipset.smbus_dev = pci_get_device(PCI_VENDOR_ID_AMD, - 0x780b, NULL); - if (!amd_chipset.smbus_dev) { - spin_unlock_irqrestore(&amd_lock, flags); - return 0; + info.smbus_dev = pci_get_device(PCI_VENDOR_ID_AMD, + 0x780b, NULL); + if (!info.smbus_dev) { + ret = 0; + goto commit; } - rev = amd_chipset.smbus_dev->revision; + + rev = info.smbus_dev->revision; if (rev >= 0x11 && rev <= 0x18) - amd_chipset.sb_type = 2; + info.sb_type = 2; } - if (amd_chipset.sb_type == 0) { - if (amd_chipset.smbus_dev) { - pci_dev_put(amd_chipset.smbus_dev); - amd_chipset.smbus_dev = NULL; + if (info.sb_type == 0) { + if (info.smbus_dev) { + pci_dev_put(info.smbus_dev); + info.smbus_dev = NULL; } - spin_unlock_irqrestore(&amd_lock, flags); - return 0; + ret = 0; + goto commit; } - amd_chipset.nb_dev = pci_get_device(PCI_VENDOR_ID_AMD, 0x9601, NULL); - if (amd_chipset.nb_dev) { - amd_chipset.nb_type = 1; + info.nb_dev = pci_get_device(PCI_VENDOR_ID_AMD, 0x9601, NULL); + if (info.nb_dev) { + info.nb_type = 1; } else { - amd_chipset.nb_dev = pci_get_device(PCI_VENDOR_ID_AMD, - 0x1510, NULL); - if (amd_chipset.nb_dev) { - amd_chipset.nb_type = 2; - } else { - amd_chipset.nb_dev = pci_get_device(PCI_VENDOR_ID_AMD, - 0x9600, NULL); - if (amd_chipset.nb_dev) - amd_chipset.nb_type = 3; + info.nb_dev = pci_get_device(PCI_VENDOR_ID_AMD, 0x1510, NULL); + if (info.nb_dev) { + info.nb_type = 2; + } else { + info.nb_dev = pci_get_device(PCI_VENDOR_ID_AMD, + 0x9600, NULL); + if (info.nb_dev) + info.nb_type = 3; } } - amd_chipset.probe_result = 1; + ret = info.probe_result = 1; printk(KERN_DEBUG "QUIRK: Enable AMD PLL fix\n"); +commit: + + spin_lock_irqsave(&amd_lock, flags); + if (amd_chipset.probe_count > 0) { + /* race - someone else was faster - drop devices */ + if (info.nb_dev) + pci_dev_put(info.nb_dev); + if (info.smbus_dev) + pci_dev_put(info.smbus_dev); + } else { + /* no race - commit the result */ + info.probe_count++; + amd_chipset = info; + } spin_unlock_irqrestore(&amd_lock, flags); - return amd_chipset.probe_result; + + return ret; } EXPORT_SYMBOL_GPL(usb_amd_find_chipset_info); -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/