On Tue, Oct 18, 2022 at 03:06:43PM +0800, liulongfang wrote:
On 2022/10/17 20:11, Jason Gunthorpe Wrote:
On Mon, Oct 17, 2022 at 05:20:34PM +0800, liulongfang wrote:
On 2022/10/14 17:20, John Garry wrote:
On 14/10/2022 03:57, Longfang Liu wrote:
+static void hisi_acc_vf_debugfs_init(struct hisi_acc_vf_core_device *hisi_acc_vdev) +{ + struct pci_dev *vf_pdev = hisi_acc_vdev->vf_dev; + struct device *dev = &vf_pdev->dev; + int ret;
+ if (!atomic_read(&hisi_acc_root_ref)) + hisi_acc_debugfs_root = debugfs_create_dir("hisi_vfio_acc", NULL); + atomic_inc(&hisi_acc_root_ref);
This looks totally racy, such that I wonder why even bother using an atomic for hisi_acc_root_ref.
When enabling VF, it is possible for multiple VMs to enable VF at the same time. The atomic variable is used to ensure that only one "hisi_vfio_acc" is created. When other VFs are enabled, it will not be created again, but will be used directly.
It is still completely racy. Use a lock
Do you have any suggested solutions?
If you want to keep it like this, use a lock around the creation.
Jason