Re: [PATCH V4] IB/uverbs: Fix race between uverbs_close and remove_one
From: Jason Gunthorpe <hidden>
Date: 2016-03-12 20:45:02
On Sat, Mar 12, 2016 at 10:18:47AM -0500, Devesh Sharma wrote:
CC: Yishai Hadas <yishaih-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
I'm still pretty convinced this is wrong... But even still:
quoted hunk
@@ -954,6 +955,17 @@ static int ib_uverbs_close(struct inode *inode, struct file *filp) struct ib_uverbs_file *file = filp->private_data; struct ib_uverbs_device *dev = file->device; struct ib_ucontext *ucontext = NULL; + struct ib_device *ib_dev; + int srcu_key; + + srcu_key = srcu_read_lock(&dev->disassociate_srcu); + ib_dev = srcu_dereference(dev->ib_dev, + &dev->disassociate_srcu); + if (!ib_dev) { + srcu_read_unlock(&dev->disassociate_srcu, srcu_key); + wait_for_completion(&file->fcomp); + goto out;
This jumps over this:
if (file->async_file) kref_put(&file->async_file->ref, ib_uverbs_release_event_file);
Which doesn't seem right. As I've said, I'm not sure how this is any different from using lists_mutex. The wait_for_completion will still block and deadlock if ib_uverbs_close is entered during the disassociate flow. Jason -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html