From: Steve Wise Date: Fri, 31 Aug 2018 14:16:03 +0000 (-0700) Subject: RDMA/uverbs: Atomically flush and mark closed the comp event queue X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=67e3816842fe6414d629c7515b955952ec40c7d7;p=linux.git RDMA/uverbs: Atomically flush and mark closed the comp event queue 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 add setting ev_queue->is_closed = 1 to ib_uverbs_comp_event_close(). Cc: stable@vger.kernel.org Fixes: 1e7710f3f656 ("IB/core: Change completion channel to use the reworked objects schema") Signed-off-by: Steve Wise Signed-off-by: Jason Gunthorpe --- diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c index 6d974e2363df2..50152c1b10045 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);