@@ -2316,10 +2316,10 @@ int vfio_ap_mdev_register(void)
matrix_dev->mdev_type.sysfs_name = VFIO_AP_MDEV_TYPE_HWVIRT;
matrix_dev->mdev_type.pretty_name = VFIO_AP_MDEV_NAME_HWVIRT;
- matrix_dev->mdev_types[0] = &matrix_dev->mdev_type;
+ matrix_dev->mdev_types = &matrix_dev->mdev_type;
ret = mdev_register_parent(&matrix_dev->parent, &matrix_dev->device,
&vfio_ap_matrix_driver,
- matrix_dev->mdev_types, 1);
+ &matrix_dev->mdev_types, 1);
if (ret)
goto err_driver;
return 0;
@@ -53,7 +53,7 @@ struct ap_matrix_dev {
struct mutex guests_lock; /* serializes access to each KVM guest */
struct mdev_parent parent;
struct mdev_type mdev_type;
- struct mdev_type *mdev_types[1];
+ struct mdev_type *mdev_types;
};
extern struct ap_matrix_dev *matrix_dev;
The vfio-ap driver and the vfio parent device provided by it (matrix_dev) support just a single mdev_type, and this is not likely to change any time soon. Despite that matrix_dev->mdev_types started out as a C99 flexible array presumably as a typo, and since the typo messed up the allocation, commit e2c8cee9f489 ("s390/vfio-ap: Fix memory allocation for mdev_types array") changed it to an array of size 1. And to make things worse mdev_types happens to be the last member of struct ap_matrix_dev. Now the problem with that is that before C99 the usual way to get something similar to a flexible array member was to use a trailing array of size 0 or 1. This is what I called fake flex array. For a while now the community is trying to get rid of fake flex arrays. And while mdev_types is not a fake flex array but an array of size one (to match the mdev interfaces nicer), it can easily be and was mistaken for a fake flex array. So, let us make mdev_types a pointer to struct mdev_type and pass in the address of that pointer as the 4th formal parameter of mdev_register_parent(). Signed-off-by: Halil Pasic <pasic@linux.ibm.com> Reviewed-by: Anthony Krowiak <akrowiak@linux.ibm.com> Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com> Reviewed-by: Eric Farman <farman@linux.ibm.com> Tested-by: Anthony Krowiak <akrowiak@linux.ibm.com> --- I've also considered switching up the order in which the members mdev_types and mdev_type are defined in struct ap_matrix_dev but decided against that because that could look to somebody like well known mistake that can be made when using fake flex arrays. --- drivers/s390/crypto/vfio_ap_ops.c | 4 ++-- drivers/s390/crypto/vfio_ap_private.h | 2 +- 2 files changed, 3 insertions(+), 3 deletions(-)