From: Chengchang Tang <tangchengchang@huawei.com>
Provide a new api rdma_user_mmap_disassociate() for drivers to
disassociate mmap pages for a device.
Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>
Signed-off-by: Junxian Huang <huangjunxian6@hisilicon.com>
---
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)) {
+ 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);
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);
+ 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,
--
2.33.0On Wed, Aug 28, 2024 at 02:46:04PM +0800, Junxian Huang wrote:
> From: Chengchang Tang <tangchengchang@huawei.com>
>
> Provide a new api rdma_user_mmap_disassociate() for drivers to
> disassociate mmap pages for a device.
>
> Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>
> Signed-off-by: Junxian Huang <huangjunxian6@hisilicon.com>
> ---
> 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
>
>
On 2024/9/2 14:57, Leon Romanovsky wrote:
> On Wed, Aug 28, 2024 at 02:46:04PM +0800, Junxian Huang wrote:
>> From: Chengchang Tang <tangchengchang@huawei.com>
>>
>> Provide a new api rdma_user_mmap_disassociate() for drivers to
>> disassociate mmap pages for a device.
>>
>> Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>
>> Signed-off-by: Junxian Huang <huangjunxian6@hisilicon.com>
>> ---
>> 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?
>
The original thought was that ib_uverbs_mmap() reads ufile->disassociated while
uverbs_user_mmap_disassociate() writes it, and there might be a racing. We tried
to use atomic_t to avoid racing without adding locks.
But I looked into the code again and now I think ufile->disassociated is not
sufficient to deal with the racing like this:
ib_uverbs_mmap() uverbs_user_mmap_disassociate()
---------------- ------------------------------
atomic_read(&file->disassociated) == 0
atomic_set(&ufile->disassociated, 1)
all mmaps from the list are zapped
ucontext->device->ops.mmap(ucontext, vma)
rdma_user_mmap_io()
rdma_umap_priv_init() adds a new mmap to the list
So we may still need a lock, and ufile->disassociated can be bool now, something like:
@@ -700,9 +702,17 @@ static int ib_uverbs_mmap(struct file *filp, struct vm_area_struct *vma)
ret = PTR_ERR(ucontext);
goto out;
}
+
+ mutex_lock(&file->disassociation_lock);
+ if (file->disassociated) {
+ ret = -EPERM;
+ goto out;
+ }
+
vma->vm_ops = &rdma_umap_ops;
ret = ucontext->device->ops.mmap(ucontext, vma);
out:
+ mutex_unlock(&file->disassociation_lock);
srcu_read_unlock(&file->device->disassociate_srcu, srcu_key);
return ret;
}
Similar changes on rdma_umap_open():
@@ -723,10 +733,12 @@ 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.
*/
- if (!ufile->ucontext)
+ if (!ufile->ucontext || ufile->disassociated)
goto out_unlock;
priv = kzalloc(sizeof(*priv), GFP_KERNEL);
@@ -734,10 +746,12 @@ 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:
/*
>>
>> 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.
>
We must hold the rwsem because of the lockdep. The newly introduced lock
is also needed to prevent the racing that one thread is calling
rdma_user_mmap_disassociate(), while the other thread is calling
ib_uverbs_mmap() or rdma_umap_open().
Thanks,
Junxian
> 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
>>
>>
On Mon, Sep 02, 2024 at 09:32:10PM +0800, Junxian Huang wrote:
>
>
> On 2024/9/2 14:57, Leon Romanovsky wrote:
> > On Wed, Aug 28, 2024 at 02:46:04PM +0800, Junxian Huang wrote:
> >> From: Chengchang Tang <tangchengchang@huawei.com>
> >>
> >> Provide a new api rdma_user_mmap_disassociate() for drivers to
> >> disassociate mmap pages for a device.
> >>
> >> Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>
> >> Signed-off-by: Junxian Huang <huangjunxian6@hisilicon.com>
> >> ---
> >> 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?
> >
>
> The original thought was that ib_uverbs_mmap() reads ufile->disassociated while
> uverbs_user_mmap_disassociate() writes it, and there might be a racing. We tried
> to use atomic_t to avoid racing without adding locks.
atomic_t is never a replacement for locks. It is a way to provide
coherent view of the data between CPUs and makes sure that write/read is
not interrupted.
Thanks
On Tue, Sep 03, 2024 at 10:09:22AM +0300, Leon Romanovsky wrote: > > The original thought was that ib_uverbs_mmap() reads ufile->disassociated while > > uverbs_user_mmap_disassociate() writes it, and there might be a racing. We tried > > to use atomic_t to avoid racing without adding locks. > > atomic_t is never a replacement for locks. It is a way to provide > coherent view of the data between CPUs and makes sure that write/read is > not interrupted. Yes, add a lock, like I said Jason
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