From 0dd1b7fc3e7d30802d5839f6bf8957023b437ad4 Mon Sep 17 00:00:00 2001 From: Jason Gunthorpe Date: Fri, 25 Jun 2021 12:56:04 -0300 Subject: [PATCH] vfio/mtty: Delete mdev_devices_list Dan points out that an error case left things on this list. It is also missing locking in available_instances_show(). Further study shows the list isn't needed at all, just store the total ports in use in an atomic and delete the whole thing. Reported-by: Dan Carpenter Fixes: 09177ac91921 ("vfio/mtty: Convert to use vfio_register_group_dev()") Signed-off-by: Jason Gunthorpe Link: https://lore.kernel.org/r/0-v1-0bc56b362ca7+62-mtty_used_ports_jgg@nvidia.com Reviewed-by: Cornelia Huck Signed-off-by: Alex Williamson --- samples/vfio-mdev/mtty.c | 24 ++++++------------------ 1 file changed, 6 insertions(+), 18 deletions(-) diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c index faf9b8e..ffbaf07 100644 --- a/samples/vfio-mdev/mtty.c +++ b/samples/vfio-mdev/mtty.c @@ -144,8 +144,7 @@ struct mdev_state { int nr_ports; }; -static struct mutex mdev_list_lock; -static struct list_head mdev_devices_list; +static atomic_t mdev_used_ports; static const struct file_operations vd_fops = { .owner = THIS_MODULE, @@ -733,15 +732,13 @@ static int mtty_probe(struct mdev_device *mdev) mtty_create_config_space(mdev_state); - mutex_lock(&mdev_list_lock); - list_add(&mdev_state->next, &mdev_devices_list); - mutex_unlock(&mdev_list_lock); - ret = vfio_register_group_dev(&mdev_state->vdev); if (ret) { kfree(mdev_state); return ret; } + atomic_add(mdev_state->nr_ports, &mdev_used_ports); + dev_set_drvdata(&mdev->dev, mdev_state); return 0; } @@ -750,10 +747,8 @@ static void mtty_remove(struct mdev_device *mdev) { struct mdev_state *mdev_state = dev_get_drvdata(&mdev->dev); + atomic_sub(mdev_state->nr_ports, &mdev_used_ports); vfio_unregister_group_dev(&mdev_state->vdev); - mutex_lock(&mdev_list_lock); - list_del(&mdev_state->next); - mutex_unlock(&mdev_list_lock); kfree(mdev_state->vconfig); kfree(mdev_state); @@ -1274,14 +1269,10 @@ static ssize_t available_instances_show(struct mdev_type *mtype, struct mdev_type_attribute *attr, char *buf) { - struct mdev_state *mds; unsigned int ports = mtype_get_type_group_id(mtype) + 1; - int used = 0; - list_for_each_entry(mds, &mdev_devices_list, next) - used += mds->nr_ports; - - return sprintf(buf, "%d\n", (MAX_MTTYS - used)/ports); + return sprintf(buf, "%d\n", + (MAX_MTTYS - atomic_read(&mdev_used_ports)) / ports); } static MDEV_TYPE_ATTR_RO(available_instances); @@ -1395,9 +1386,6 @@ static int __init mtty_dev_init(void) ret = mdev_register_device(&mtty_dev.dev, &mdev_fops); if (ret) goto err_device; - - mutex_init(&mdev_list_lock); - INIT_LIST_HEAD(&mdev_devices_list); return 0; err_device: -- 2.7.4