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Commit 5b0948df authored by Emil Tantilov's avatar Emil Tantilov Committed by Bjorn Helgaas
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PCI: Lock each enable/disable num_vfs operation in sysfs 



Enabling/disabling SRIOV via sysfs by echo-ing multiple values
simultaneously:

  # echo 63 > /sys/class/net/ethX/device/sriov_numvfs&
  # echo 63 > /sys/class/net/ethX/device/sriov_numvfs

  # sleep 5

  # echo 0 > /sys/class/net/ethX/device/sriov_numvfs&
  # echo 0 > /sys/class/net/ethX/device/sriov_numvfs

results in the following bug:

  kernel BUG at drivers/pci/iov.c:495!
  invalid opcode: 0000 [#1] SMP
  CPU: 1 PID: 8050 Comm: bash Tainted: G   W   4.9.0-rc7-net-next #2092
  RIP: 0010:[<ffffffff813b1647>]
	    [<ffffffff813b1647>] pci_iov_release+0x57/0x60

  Call Trace:
   [<ffffffff81391726>] pci_release_dev+0x26/0x70
   [<ffffffff8155be6e>] device_release+0x3e/0xb0
   [<ffffffff81365ee7>] kobject_cleanup+0x67/0x180
   [<ffffffff81365d9d>] kobject_put+0x2d/0x60
   [<ffffffff8155bc27>] put_device+0x17/0x20
   [<ffffffff8139c08a>] pci_dev_put+0x1a/0x20
   [<ffffffff8139cb6b>] pci_get_dev_by_id+0x5b/0x90
   [<ffffffff8139cca5>] pci_get_subsys+0x35/0x40
   [<ffffffff8139ccc8>] pci_get_device+0x18/0x20
   [<ffffffff8139ccfb>] pci_get_domain_bus_and_slot+0x2b/0x60
   [<ffffffff813b09e7>] pci_iov_remove_virtfn+0x57/0x180
   [<ffffffff813b0b95>] pci_disable_sriov+0x65/0x140
   [<ffffffffa00a1af7>] ixgbe_disable_sriov+0xc7/0x1d0 [ixgbe]
   [<ffffffffa00a1e9d>] ixgbe_pci_sriov_configure+0x3d/0x170 [ixgbe]
   [<ffffffff8139d28c>] sriov_numvfs_store+0xdc/0x130
  ...
  RIP  [<ffffffff813b1647>] pci_iov_release+0x57/0x60

Use the existing mutex lock to protect each enable/disable operation.

Signed-off-by: default avatarEmil Tantilov <emil.s.tantilov@intel.com>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: default avatarGavin Shan <gwshan@linux.vnet.ibm.com>
CC: Alexander Duyck <alexander.h.duyck@intel.com>
parent 7184f5b4

drivers/pci/iov.c

+0 −7
Original line number Diff line number Diff line
@@ -124,7 +124,6 @@ int pci_iov_add_virtfn(struct pci_dev *dev, int id, int reset) 
	struct pci_sriov *iov = dev->sriov;

	struct pci_bus *bus;



	mutex_lock(&iov->dev->sriov->lock);

	bus = virtfn_add_bus(dev->bus, pci_iov_virtfn_bus(dev, id));

	if (!bus)

		goto failed;
@@ -162,7 +161,6 @@ int pci_iov_add_virtfn(struct pci_dev *dev, int id, int reset) 
		__pci_reset_function(virtfn);



	pci_device_add(virtfn, virtfn->bus);

	mutex_unlock(&iov->dev->sriov->lock);



	pci_bus_add_device(virtfn);

	sprintf(buf, "virtfn%u", id);
@@ -181,12 +179,10 @@ int pci_iov_add_virtfn(struct pci_dev *dev, int id, int reset) 
	sysfs_remove_link(&dev->dev.kobj, buf);

failed1:

	pci_dev_put(dev);

	mutex_lock(&iov->dev->sriov->lock);

	pci_stop_and_remove_bus_device(virtfn);

failed0:

	virtfn_remove_bus(dev->bus, bus);

failed:

	mutex_unlock(&iov->dev->sriov->lock);



	return rc;

}
@@ -195,7 +191,6 @@ void pci_iov_remove_virtfn(struct pci_dev *dev, int id, int reset) 
{

	char buf[VIRTFN_ID_LEN];

	struct pci_dev *virtfn;

	struct pci_sriov *iov = dev->sriov;



	virtfn = pci_get_domain_bus_and_slot(pci_domain_nr(dev->bus),

					     pci_iov_virtfn_bus(dev, id),
@@ -218,10 +213,8 @@ void pci_iov_remove_virtfn(struct pci_dev *dev, int id, int reset) 
	if (virtfn->dev.kobj.sd)

		sysfs_remove_link(&virtfn->dev.kobj, "physfn");



	mutex_lock(&iov->dev->sriov->lock);

	pci_stop_and_remove_bus_device(virtfn);

	virtfn_remove_bus(dev->bus, virtfn->bus);

	mutex_unlock(&iov->dev->sriov->lock);



	/* balance pci_get_domain_bus_and_slot() */

	pci_dev_put(virtfn);

drivers/pci/pci-sysfs.c

+16 −7
Original line number Diff line number Diff line
@@ -472,6 +472,7 @@ static ssize_t sriov_numvfs_store(struct device *dev, 
				  const char *buf, size_t count)

{

	struct pci_dev *pdev = to_pci_dev(dev);

	struct pci_sriov *iov = pdev->sriov;

	int ret;

	u16 num_vfs;
@@ -482,38 +483,46 @@ static ssize_t sriov_numvfs_store(struct device *dev, 
	if (num_vfs > pci_sriov_get_totalvfs(pdev))

		return -ERANGE;



	mutex_lock(&iov->dev->sriov->lock);



	if (num_vfs == pdev->sriov->num_VFs)

		return count;		/* no change */

		goto exit;



	/* is PF driver loaded w/callback */

	if (!pdev->driver || !pdev->driver->sriov_configure) {

		dev_info(&pdev->dev, "Driver doesn't support SRIOV configuration via sysfs\n");

		return -ENOSYS;

		ret = -ENOENT;

		goto exit;

	}



	if (num_vfs == 0) {

		/* disable VFs */

		ret = pdev->driver->sriov_configure(pdev, 0);

		if (ret < 0)

			return ret;

		return count;

		goto exit;

	}



	/* enable VFs */

	if (pdev->sriov->num_VFs) {

		dev_warn(&pdev->dev, "%d VFs already enabled. Disable before enabling %d VFs\n",

			 pdev->sriov->num_VFs, num_vfs);

		return -EBUSY;

		ret = -EBUSY;

		goto exit;

	}



	ret = pdev->driver->sriov_configure(pdev, num_vfs);

	if (ret < 0)

		return ret;

		goto exit;



	if (ret != num_vfs)

		dev_warn(&pdev->dev, "%d VFs requested; only %d enabled\n",

			 num_vfs, ret);



exit:

	mutex_unlock(&iov->dev->sriov->lock);



	if (ret < 0)

		return ret;



	return count;

}

drivers/pci/pci.h

+1 −1
Original line number Diff line number Diff line
@@ -270,7 +270,7 @@ struct pci_sriov { 
	u16 driver_max_VFs;	/* max num VFs driver supports */

	struct pci_dev *dev;	/* lowest numbered PF */

	struct pci_dev *self;	/* this PF */

	struct mutex lock;	/* lock for VF bus */

	struct mutex lock;	/* lock for setting sriov_numvfs in sysfs */

	resource_size_t barsz[PCI_SRIOV_NUM_BARS];	/* VF BAR size */

};