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RDMA/core: Provide rdma_user_mmap_disassociate() to disassociate mmap pages

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Provide a new api rdma_user_mmap_disassociate() for drivers to
disassociate mmap pages for a device.

Since drivers can now disassociate mmaps by calling this api,
introduce a new disassociation_lock to specifically prevent
races between this disassociation process and new mmaps. And
thus the old hw_destroy_rwsem is not needed in this api.

Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>
Signed-off-by: Junxian Huang <huangjunxian6@hisilicon.com>
Link: https://patch.msgid.link/20240927103323.1897094-2-huangjunxian6@hisilicon.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>
This commit is contained in:
Chengchang Tang 2024-09-27 18:33:22 +08:00 committed by Leon Romanovsky
parent 8cf0b93919
commit 51976c6cd7
3 changed files with 51 additions and 2 deletions
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2
drivers/infiniband/core/uverbs.h
View File

@ -160,6 +160,8 @@ struct ib_uverbs_file {
struct page *disassociate_page;
struct xarray idr;
struct mutex disassociation_lock;
};
struct ib_uverbs_event {

43
drivers/infiniband/core/uverbs_main.c
View File

@ -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);
@ -698,8 +700,13 @@ static int ib_uverbs_mmap(struct file *filp, struct vm_area_struct *vma)
ret = PTR_ERR(ucontext);
goto out;
}
mutex_lock(&file->disassociation_lock);
vma->vm_ops = &rdma_umap_ops;
ret = ucontext->device->ops.mmap(ucontext, vma);
mutex_unlock(&file->disassociation_lock);
out:
srcu_read_unlock(&file->device->disassociate_srcu, srcu_key);
return ret;
@ -721,6 +728,8 @@ static void rdma_umap_open(struct vm_area_struct *vma)
/* We are racing with disassociation */
if (!down_read_trylock(&ufile->hw_destroy_rwsem))
goto out_zap;
mutex_lock(&ufile->disassociation_lock);
/*
* Disassociation already completed, the VMA should already be zapped.
*/
@ -732,10 +741,12 @@ static void rdma_umap_open(struct vm_area_struct *vma)
goto out_unlock;
rdma_umap_priv_init(priv, vma, opriv->entry);
mutex_unlock(&ufile->disassociation_lock);
up_read(&ufile->hw_destroy_rwsem);
return;
out_unlock:
mutex_unlock(&ufile->disassociation_lock);
up_read(&ufile->hw_destroy_rwsem);
out_zap:
/*
@ -819,7 +830,7 @@ 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);
while (1) {
struct mm_struct *mm = NULL;
@ -845,8 +856,10 @@ 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
@ -876,8 +889,32 @@ 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) {
if (ufile->ucontext)
uverbs_user_mmap_disassociate(ufile);
}
mutex_unlock(&uverbs_dev->lists_mutex);
}
EXPORT_SYMBOL(rdma_user_mmap_disassociate);
/*
* ib_uverbs_open() does not need the BKL:
*
@ -947,6 +984,8 @@ 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);
filp->private_data = file;
list_add_tail(&file->list, &dev->uverbs_file_list);
mutex_unlock(&dev->lists_mutex);

8
include/rdma/ib_verbs.h
View File

@ -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,