On Mon, Apr 11, 2011 at 02:26:00AM -0400, Borislav Petkov wrote: > You mean 2.6.39-rc2 right? I'm asking because I hit the same warning > with 39-rc2 now too but it didn't appear with .38 - so it has to have > snuck in after the merge window. If so, you don't need the stable tag.
You were right, just tested plain 2.6.38 and it doesn't happen. So I removed the stable tag. Here is the updated patch. >From 6b9a9018cf0b847dcd906c269d663668e67a097d Mon Sep 17 00:00:00 2001 From: Joerg Roedel <[email protected]> Date: Wed, 6 Apr 2011 13:07:53 +0200 Subject: [PATCH] USB host: Fix lockdep warning in AMD PLL quirk 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: [<ffffffff8103c0d4>] warn_slowpath_common+0x80/0x98 [<ffffffff812387e6>] ? T.492+0x24/0x26 [<ffffffff8103c101>] warn_slowpath_null+0x15/0x17 [<ffffffff81068667>] lockdep_trace_alloc+0x95/0xc2 [<ffffffff810ed9ac>] slab_pre_alloc_hook+0x18/0x3b [<ffffffff810ef227>] kmem_cache_alloc_trace+0x25/0xba [<ffffffff812387e6>] T.492+0x24/0x26 [<ffffffff81238816>] pci_get_subsys+0x2e/0x73 [<ffffffff8123886c>] pci_get_device+0x11/0x13 [<ffffffff814082a9>] 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 the warning by making all data-structure modifications on temporal storage and commiting this back into the visible structure at the end. While at it, this patch also moves the pci_dev_put calls out of the spinlocks because this function might sleep too. Signed-off-by: Joerg Roedel <[email protected]> --- drivers/usb/host/pci-quirks.c | 117 ++++++++++++++++++++++++++--------------- 1 files changed, 74 insertions(+), 43 deletions(-) diff --git a/drivers/usb/host/pci-quirks.c b/drivers/usb/host/pci-quirks.c index 1d586d4..c6eb69c 100644 --- a/drivers/usb/host/pci-quirks.c +++ b/drivers/usb/host/pci-quirks.c @@ -84,65 +84,92 @@ 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) { + amd_chipset.probe_count++; spin_unlock_irqrestore(&amd_lock, flags); return amd_chipset.probe_result; } + memset(&info, 0, sizeof(info)); + 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"); - spin_unlock_irqrestore(&amd_lock, flags); - return amd_chipset.probe_result; +commit: + + spin_lock_irqsave(&amd_lock, flags); + if (amd_chipset.probe_count > 0) { + /* race - someone else was faster - drop devices */ + + /* Mark that we where here */ + amd_chipset.probe_count++; + ret = amd_chipset.probe_result; + + spin_unlock_irqrestore(&amd_lock, flags); + + 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 ret; } EXPORT_SYMBOL_GPL(usb_amd_find_chipset_info); @@ -284,6 +311,7 @@ EXPORT_SYMBOL_GPL(usb_amd_quirk_pll_enable); void usb_amd_dev_put(void) { + struct pci_dev *nb, *smbus; unsigned long flags; spin_lock_irqsave(&amd_lock, flags); @@ -294,20 +322,23 @@ void usb_amd_dev_put(void) return; } - if (amd_chipset.nb_dev) { - pci_dev_put(amd_chipset.nb_dev); - amd_chipset.nb_dev = NULL; - } - if (amd_chipset.smbus_dev) { - pci_dev_put(amd_chipset.smbus_dev); - amd_chipset.smbus_dev = NULL; - } + /* save them to pci_dev_put outside of spinlock */ + nb = amd_chipset.nb_dev; + smbus = amd_chipset.smbus_dev; + + amd_chipset.nb_dev = NULL; + amd_chipset.smbus_dev = NULL; amd_chipset.nb_type = 0; amd_chipset.sb_type = 0; amd_chipset.isoc_reqs = 0; amd_chipset.probe_result = 0; spin_unlock_irqrestore(&amd_lock, flags); + + if (nb) + pci_dev_put(nb); + if (smbus) + pci_dev_put(amd_chipset.smbus_dev); } EXPORT_SYMBOL_GPL(usb_amd_dev_put); -- 1.7.1 -- AMD Operating System Research Center Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach General Managers: Alberto Bozzo, Andrew Bowd Registration: Dornach, Landkr. 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