On Wed, Aug 28, 2024 at 02:46:04PM +0800, Junxian Huang wrote:
> From: Chengchang Tang <tangchengchang@xxxxxxxxxx>
>
> Provide a new api rdma_user_mmap_disassociate() for drivers to
> disassociate mmap pages for a device.
>
> Signed-off-by: Chengchang Tang <tangchengchang@xxxxxxxxxx>
> Signed-off-by: Junxian Huang <huangjunxian6@xxxxxxxxxxxxx>
> ---
> drivers/infiniband/core/uverbs.h | 3 ++
> drivers/infiniband/core/uverbs_main.c | 45 +++++++++++++++++++++++++--
> include/rdma/ib_verbs.h | 8 +++++
> 3 files changed, 54 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/infiniband/core/uverbs.h b/drivers/infiniband/core/uverbs.h
> index 821d93c8f712..0999d27cb1c9 100644
> --- a/drivers/infiniband/core/uverbs.h
> +++ b/drivers/infiniband/core/uverbs.h
> @@ -160,6 +160,9 @@ struct ib_uverbs_file {
> struct page *disassociate_page;
>
> struct xarray idr;
> +
> + struct mutex disassociation_lock;
> + atomic_t disassociated;
> };
>
> struct ib_uverbs_event {
> diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c
> index bc099287de9a..589f27c09a2e 100644
> --- a/drivers/infiniband/core/uverbs_main.c
> +++ b/drivers/infiniband/core/uverbs_main.c
> @@ -76,6 +76,7 @@ static dev_t dynamic_uverbs_dev;
> static DEFINE_IDA(uverbs_ida);
> static int ib_uverbs_add_one(struct ib_device *device);
> static void ib_uverbs_remove_one(struct ib_device *device, void *client_data);
> +static struct ib_client uverbs_client;
>
> static char *uverbs_devnode(const struct device *dev, umode_t *mode)
> {
> @@ -217,6 +218,7 @@ void ib_uverbs_release_file(struct kref *ref)
>
> if (file->disassociate_page)
> __free_pages(file->disassociate_page, 0);
> + mutex_destroy(&file->disassociation_lock);
> mutex_destroy(&file->umap_lock);
> mutex_destroy(&file->ucontext_lock);
> kfree(file);
> @@ -700,6 +702,12 @@ static int ib_uverbs_mmap(struct file *filp, struct vm_area_struct *vma)
> ret = PTR_ERR(ucontext);
> goto out;
> }
> +
> + if (atomic_read(&file->disassociated)) {
I don't see any of the newly introduced locks here. If it is
intentional, it needs to be documented.
> + ret = -EPERM;
> + goto out;
> + }
> +
> vma->vm_ops = &rdma_umap_ops;
> ret = ucontext->device->ops.mmap(ucontext, vma);
> out:
> @@ -726,7 +734,7 @@ static void rdma_umap_open(struct vm_area_struct *vma)
> /*
> * Disassociation already completed, the VMA should already be zapped.
> */
> - if (!ufile->ucontext)
> + if (!ufile->ucontext || atomic_read(&ufile->disassociated))
> goto out_unlock;
>
> priv = kzalloc(sizeof(*priv), GFP_KERNEL);
> @@ -822,6 +830,8 @@ void uverbs_user_mmap_disassociate(struct ib_uverbs_file *ufile)
> struct rdma_umap_priv *priv, *next_priv;
>
> lockdep_assert_held(&ufile->hw_destroy_rwsem);
> + mutex_lock(&ufile->disassociation_lock);
> + atomic_set(&ufile->disassociated, 1);
Why do you use atomic_t and not regular bool?
>
> while (1) {
> struct mm_struct *mm = NULL;
> @@ -847,8 +857,10 @@ void uverbs_user_mmap_disassociate(struct ib_uverbs_file *ufile)
> break;
> }
> mutex_unlock(&ufile->umap_lock);
> - if (!mm)
> + if (!mm) {
> + mutex_unlock(&ufile->disassociation_lock);
> return;
> + }
>
> /*
> * The umap_lock is nested under mmap_lock since it used within
> @@ -878,8 +890,34 @@ void uverbs_user_mmap_disassociate(struct ib_uverbs_file *ufile)
> mmap_read_unlock(mm);
> mmput(mm);
> }
> +
> + mutex_unlock(&ufile->disassociation_lock);
> }
>
> +/**
> + * rdma_user_mmap_disassociate() - Revoke mmaps for a device
> + * @device: device to revoke
> + *
> + * This function should be called by drivers that need to disable mmaps for the
> + * device, for instance because it is going to be reset.
> + */
> +void rdma_user_mmap_disassociate(struct ib_device *device)
> +{
> + struct ib_uverbs_device *uverbs_dev =
> + ib_get_client_data(device, &uverbs_client);
> + struct ib_uverbs_file *ufile;
> +
> + mutex_lock(&uverbs_dev->lists_mutex);
> + list_for_each_entry(ufile, &uverbs_dev->uverbs_file_list, list) {
> + down_read(&ufile->hw_destroy_rwsem);
I personally don't understand this locking scheme at all. I see newly
introduced locks mixed together some old locks.
Jason, do you agree with this proposed locking scheme?
Thanks
> + if (ufile->ucontext && !atomic_read(&ufile->disassociated))
> + uverbs_user_mmap_disassociate(ufile);
> + up_read(&ufile->hw_destroy_rwsem);
> + }
> + mutex_unlock(&uverbs_dev->lists_mutex);
> +}
> +EXPORT_SYMBOL(rdma_user_mmap_disassociate);
> +
> /*
> * ib_uverbs_open() does not need the BKL:
> *
> @@ -949,6 +987,9 @@ static int ib_uverbs_open(struct inode *inode, struct file *filp)
> mutex_init(&file->umap_lock);
> INIT_LIST_HEAD(&file->umaps);
>
> + mutex_init(&file->disassociation_lock);
> + atomic_set(&file->disassociated, 0);
> +
> filp->private_data = file;
> list_add_tail(&file->list, &dev->uverbs_file_list);
> mutex_unlock(&dev->lists_mutex);
> diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
> index a1dcf812d787..09b80c8253e2 100644
> --- a/include/rdma/ib_verbs.h
> +++ b/include/rdma/ib_verbs.h
> @@ -2948,6 +2948,14 @@ int rdma_user_mmap_entry_insert_range(struct ib_ucontext *ucontext,
> size_t length, u32 min_pgoff,
> u32 max_pgoff);
>
> +#if IS_ENABLED(CONFIG_INFINIBAND_USER_ACCESS)
> +void rdma_user_mmap_disassociate(struct ib_device *device);
> +#else
> +static inline void rdma_user_mmap_disassociate(struct ib_device *device)
> +{
> +}
> +#endif
> +
> static inline int
> rdma_user_mmap_entry_insert_exact(struct ib_ucontext *ucontext,
> struct rdma_user_mmap_entry *entry,
> --
> 2.33.0
>
>
