[PATCH AUTOSEL 5.6 071/606] RDMA/uverbs: Do not discard the IB_EVENT_DEVICE_FATAL event

Sasha Levin
2020-06-09T00:37:56Z

From: Jason Gunthorpe <jgg@mellanox.com>

commit c485b19d52c4ba269dfd027945dee81755fdd530 upstream.

The commit below moved all of the destruction to the disassociate step and
cleaned up the event channel during destroy_uobj.

However, when ib_uverbs_free_hw_resources() pushes IB_EVENT_DEVICE_FATAL
and then immediately goes to destroy all uobjects this causes
ib_uverbs_free_event_queue() to discard the queued event if userspace
hasn't already read() it.

Unlike all other event queues async FD needs to defer the
ib_uverbs_free_event_queue() until FD release. This still unregisters the
handler from the IB device during disassociation.

Fixes: 3e032c0e92aa ("RDMA/core: Make ib_uverbs_async_event_file into a uobject")
Link: https://lore.kernel.org/r/20200507063348.98713-2-leon@kernel.org
Signed-off-by: Yishai Hadas <yishaih@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/infiniband/core/rdma_core.c | 3 ++-
drivers/infiniband/core/uverbs.h | 1 +
drivers/infiniband/core/uverbs_main.c | 2 +-
.../core/uverbs_std_types_async_fd.c | 26 ++++++++++++++++++-
4 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/drivers/infiniband/core/rdma_core.c b/drivers/infiniband/core/rdma_core.c
index 177333d8bcda..bf8e149d3191 100644
--- a/drivers/infiniband/core/rdma_core.c
+++ b/drivers/infiniband/core/rdma_core.c
@@ -459,7 +459,8 @@ alloc_begin_fd_uobject(const struct uverbs_api_object *obj,
struct ib_uobject *uobj;
struct file *filp;

- if (WARN_ON(fd_type->fops->release != &uverbs_uobject_fd_release))
+ if (WARN_ON(fd_type->fops->release != &uverbs_uobject_fd_release &&
+ fd_type->fops->release != &uverbs_async_event_release))
return ERR_PTR(-EINVAL);

new_fd = get_unused_fd_flags(O_CLOEXEC);
diff --git a/drivers/infiniband/core/uverbs.h b/drivers/infiniband/core/uverbs.h
index 7df71983212d..2673cb1cd655 100644
--- a/drivers/infiniband/core/uverbs.h
+++ b/drivers/infiniband/core/uverbs.h
@@ -219,6 +219,7 @@ void ib_uverbs_init_event_queue(struct ib_uverbs_event_queue *ev_queue);
void ib_uverbs_init_async_event_file(struct ib_uverbs_async_event_file *ev_file);
void ib_uverbs_free_event_queue(struct ib_uverbs_event_queue *event_queue);
void ib_uverbs_flow_resources_free(struct ib_uflow_resources *uflow_res);
+int uverbs_async_event_release(struct inode *inode, struct file *filp);

int ib_alloc_ucontext(struct uverbs_attr_bundle *attrs);
int ib_init_ucontext(struct uverbs_attr_bundle *attrs);
diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c
index 17fc25db0311..cb5b59123d8f 100644
--- a/drivers/infiniband/core/uverbs_main.c
+++ b/drivers/infiniband/core/uverbs_main.c
@@ -346,7 +346,7 @@ const struct file_operations uverbs_async_event_fops = {
.owner = THIS_MODULE,
.read = ib_uverbs_async_event_read,
.poll = ib_uverbs_async_event_poll,
- .release = uverbs_uobject_fd_release,
+ .release = uverbs_async_event_release,
.fasync = ib_uverbs_async_event_fasync,
.llseek = no_llseek,
};
diff --git a/drivers/infiniband/core/uverbs_std_types_async_fd.c b/drivers/infiniband/core/uverbs_std_types_async_fd.c
index 82ec0806b34b..462deb506b16 100644
--- a/drivers/infiniband/core/uverbs_std_types_async_fd.c
+++ b/drivers/infiniband/core/uverbs_std_types_async_fd.c
@@ -26,10 +26,34 @@ static int uverbs_async_event_destroy_uobj(struct ib_uobject *uobj,
container_of(uobj, struct ib_uverbs_async_event_file, uobj);

ib_unregister_event_handler(&event_file->event_handler);
- ib_uverbs_free_event_queue(&event_file->ev_queue);
return 0;
}

+int uverbs_async_event_release(struct inode *inode, struct file *filp)
+{
+ struct ib_uverbs_async_event_file *event_file;
+ struct ib_uobject *uobj = filp->private_data;
+ int ret;
+
+ if (!uobj)
+ return uverbs_uobject_fd_release(inode, filp);
+
+ event_file =
+ container_of(uobj, struct ib_uverbs_async_event_file, uobj);
+
+ /*
+ * The async event FD has to deliver IB_EVENT_DEVICE_FATAL even after
+ * disassociation, so cleaning the event list must only happen after
+ * release. The user knows it has reached the end of the event stream
+ * when it sees IB_EVENT_DEVICE_FATAL.
+ */
+ uverbs_uobject_get(uobj);
+ ret = uverbs_uobject_fd_release(inode, filp);
+ ib_uverbs_free_event_queue(&event_file->ev_queue);
+ uverbs_uobject_put(uobj);
+ return ret;
+}
+
DECLARE_UVERBS_NAMED_METHOD(
UVERBS_METHOD_ASYNC_EVENT_ALLOC,
UVERBS_ATTR_FD(UVERBS_ATTR_ASYNC_EVENT_ALLOC_FD_HANDLE,
--
2.25.1