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Commit 9ab7927b authored by Joerg Roedel's avatar Joerg Roedel Committed by Greg Kroah-Hartman
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USB host: Fix lockdep warning in AMD PLL quirk 



Booting latest kernel 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: default avatarJoerg Roedel <joerg.roedel@amd.com>
Acked-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 16a2f970

drivers/usb/host/pci-quirks.c

+74 −43
Original line number Diff line number Diff line
@@ -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,

		info.smbus_dev = pci_get_device(PCI_VENDOR_ID_AMD,

						0x780b, NULL);

		if (!amd_chipset.smbus_dev) {

			spin_unlock_irqrestore(&amd_lock, flags);

			return 0;

		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;

		info.nb_dev = pci_get_device(PCI_VENDOR_ID_AMD, 0x1510, NULL);

		if (info.nb_dev) {

			info.nb_type = 2;

		} else {

			amd_chipset.nb_dev = pci_get_device(PCI_VENDOR_ID_AMD,

			info.nb_dev = pci_get_device(PCI_VENDOR_ID_AMD,

						     0x9600, NULL);

			if (amd_chipset.nb_dev)

				amd_chipset.nb_type = 3;

			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 */



		/* 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 amd_chipset.probe_result;

	}



	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);

	/* save them to pci_dev_put outside of spinlock */

	nb    = amd_chipset.nb_dev;

	smbus = amd_chipset.smbus_dev;



	amd_chipset.nb_dev = NULL;

	}

	if (amd_chipset.smbus_dev) {

		pci_dev_put(amd_chipset.smbus_dev);

	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(smbus);

}

EXPORT_SYMBOL_GPL(usb_amd_dev_put);