Currently a uverbs completion event queue is flushed of events in
ib_uverbs_comp_event_close() with the queue spinlock held and then
released. Yet setting ev_queue->is_closed is not set until later in
uverbs_hot_unplug_completion_event_file().
In between the time ib_uverbs_comp_event_close() releases the lock
and uverbs_hot_unplug_completion_event_file() acquires the lock, a
completion event can arrive and be inserted into the event queue by
ib_uverbs_comp_handler().
This can cause a "double add" list_add warning or crash depending on
the kernel configuration, or a memory leak because the event is never
dequeued since the queue is already closed down.
So move the setting of ev_queue->is_closed to
ib_uverbs_comp_event_close().
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 1e7710f3f656 ("IB/core: Change completion channel to use the reworked objects schema")
Signed-off-by: Steve Wise <swise@xxxxxxxxxxxxxxxxxxxxx>
---
I added the RFC tag because I'm not sure removing setting
is_closed in uverbs_hot_unplug_completion_event_file() is correct.
Can uverbs_hot_unplug_completion_event_file() be called w/o
ib_uverbs_comp_event_close() being called first? Should is_closed be
set in both places?
---
drivers/infiniband/core/uverbs_main.c | 1 +
drivers/infiniband/core/uverbs_std_types.c | 4 ----
2 files changed, 1 insertion(+), 4 deletions(-)
diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c
index 823beca448e1..b3ef7db68bde 100644
--- a/drivers/infiniband/core/uverbs_main.c
+++ b/drivers/infiniband/core/uverbs_main.c
@@ -440,6 +440,7 @@ static int ib_uverbs_comp_event_close(struct inode *inode, struct file *filp)
list_del(&entry->obj_list);
kfree(entry);
}
+ file->ev_queue.is_closed = 1;
spin_unlock_irq(&file->ev_queue.lock);
uverbs_close_fd(filp);
diff --git a/drivers/infiniband/core/uverbs_std_types.c b/drivers/infiniband/core/uverbs_std_types.c
index 203cc96ac6f5..76fc9b7fec59 100644
--- a/drivers/infiniband/core/uverbs_std_types.c
+++ b/drivers/infiniband/core/uverbs_std_types.c
@@ -199,10 +199,6 @@ static int uverbs_hot_unplug_completion_event_file(struct ib_uobject *uobj,
uobj);
struct ib_uverbs_event_queue *event_queue = &comp_event_file->ev_queue;
- spin_lock_irq(&event_queue->lock);
- event_queue->is_closed = 1;
- spin_unlock_irq(&event_queue->lock);
-
if (why == RDMA_REMOVE_DRIVER_REMOVE) {
wake_up_interruptible(&event_queue->poll_wait);
kill_fasync(&event_queue->async_queue, SIGIO, POLL_IN);
--
1.8.3.1
