Commit 774a1fa8 authored by Niklas Schnelle's avatar Niklas Schnelle Committed by Heiko Carstens
Browse files

s390/pci: Serialize device addition and removal 



Prior changes ensured that when zpci_release_device() is called and it
removed the zdev from the zpci_list this instance can not be found via
the zpci_list anymore even while allowing re-add of reserved devices.
This only accounts for the overall lifetime and zpci_list addition and
removal, it does not yet prevent concurrent add of a new instance for
the same underlying device. Such concurrent add would subsequently cause
issues such as attempted re-use of the same IOMMU sysfs directory and is
generally undesired.

Introduce a new zpci_add_remove_lock mutex to serialize adding a new
device with removal. Together this ensures that if a struct zpci_dev is
not found in the zpci_list it was either already removed and torn down,
or its removal and tear down is in progress with the
zpci_add_remove_lock held.

Cc: stable@vger.kernel.org
Fixes: a46044a9 ("s390/pci: fix zpci_zdev_put() on reserve")
Reviewed-by: default avatarGerd Bayer <gbayer@linux.ibm.com>
Tested-by: default avatarGerd Bayer <gbayer@linux.ibm.com>
Signed-off-by: default avatarNiklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
parent 4b1815a5

arch/s390/pci/pci.c

+7 −0
Original line number Diff line number Diff line
@@ -45,6 +45,7 @@ 
/* list of all detected zpci devices */

static LIST_HEAD(zpci_list);

static DEFINE_SPINLOCK(zpci_list_lock);

static DEFINE_MUTEX(zpci_add_remove_lock);



static DECLARE_BITMAP(zpci_domain, ZPCI_DOMAIN_BITMAP_SIZE);

static DEFINE_SPINLOCK(zpci_domain_lock);
@@ -74,7 +75,9 @@ void zpci_zdev_put(struct zpci_dev *zdev) 
{

	if (!zdev)

		return;

	mutex_lock(&zpci_add_remove_lock);

	kref_put_lock(&zdev->kref, zpci_release_device, &zpci_list_lock);

	mutex_unlock(&zpci_add_remove_lock);

}



struct zpci_dev *get_zdev_by_fid(u32 fid)
@@ -844,6 +847,7 @@ int zpci_add_device(struct zpci_dev *zdev) 
{

	int rc;



	mutex_lock(&zpci_add_remove_lock);

	zpci_dbg(1, "add fid:%x, fh:%x, c:%d\n", zdev->fid, zdev->fh, zdev->state);

	rc = zpci_init_iommu(zdev);

	if (rc)
@@ -857,12 +861,14 @@ int zpci_add_device(struct zpci_dev *zdev) 
	spin_lock(&zpci_list_lock);

	list_add_tail(&zdev->entry, &zpci_list);

	spin_unlock(&zpci_list_lock);

	mutex_unlock(&zpci_add_remove_lock);

	return 0;



error_destroy_iommu:

	zpci_destroy_iommu(zdev);

error:

	zpci_dbg(0, "add fid:%x, rc:%d\n", zdev->fid, rc);

	mutex_unlock(&zpci_add_remove_lock);

	return rc;

}
@@ -953,6 +959,7 @@ void zpci_release_device(struct kref *kref) 
{

	struct zpci_dev *zdev = container_of(kref, struct zpci_dev, kref);



	lockdep_assert_held(&zpci_add_remove_lock);

	WARN_ON(zdev->state != ZPCI_FN_STATE_RESERVED);

	/*

	 * We already hold zpci_list_lock thanks to kref_put_lock().