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s390/pci: Serialize device addition and removal

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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: a46044a92a ("s390/pci: fix zpci_zdev_put() on reserve")
Reviewed-by: Gerd Bayer <gbayer@linux.ibm.com>
Tested-by: Gerd Bayer <gbayer@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
Niklas Schnelle 2025-05-22 14:13:15 +02:00 committed by Heiko Carstens
parent 4b1815a52d
commit 774a1fa880
1 changed files with 7 additions and 0 deletions
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7
arch/s390/pci/pci.c
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@ -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().