6.12-stable review patch. If anyone has any objections, please let me know.
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From: Niklas Schnelle schnelle@linux.ibm.com
commit 774a1fa880bc949d88b5ddec9494a13be733dfa8 upstream.
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: a46044a92add ("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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/s390/pci/pci.c | 7 +++++++ 1 file changed, 7 insertions(+)
--- a/arch/s390/pci/pci.c +++ b/arch/s390/pci/pci.c @@ -44,6 +44,7 @@ /* 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); @@ -73,7 +74,9 @@ 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) @@ -838,6 +841,7 @@ int zpci_add_device(struct zpci_dev *zde { 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) @@ -851,12 +855,14 @@ int zpci_add_device(struct zpci_dev *zde 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; }
@@ -947,6 +953,7 @@ void zpci_release_device(struct kref *kr { 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().