IB/uverbs: Avoid a crash on device hot remove
Wait until all users have closed their device context before allowing device unregistration to complete. This prevents a crash caused by referring to stale data structures. A better solution would be to have a way to revoke contexts rather than waiting for userspace to close the context, but that's a much bigger change that will have to wait. For now let's at least avoid the crash. Signed-off-by: Jack Morgenstein <jackm@mellanox.co.il> Signed-off-by: Michael S. Tsirkin <mst@mellanox.co.il> Signed-off-by: Roland Dreier <rolandd@cisco.com>
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@ -42,6 +42,7 @@
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#include <linux/kref.h>
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#include <linux/idr.h>
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#include <linux/mutex.h>
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#include <linux/completion.h>
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#include <rdma/ib_verbs.h>
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#include <rdma/ib_user_verbs.h>
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@ -69,6 +70,7 @@
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struct ib_uverbs_device {
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struct kref ref;
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struct completion comp;
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int devnum;
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struct cdev *dev;
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struct class_device *class_dev;
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@ -122,7 +122,7 @@ static void ib_uverbs_release_dev(struct kref *ref)
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struct ib_uverbs_device *dev =
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container_of(ref, struct ib_uverbs_device, ref);
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kfree(dev);
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complete(&dev->comp);
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}
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void ib_uverbs_release_ucq(struct ib_uverbs_file *file,
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@ -740,6 +740,7 @@ static void ib_uverbs_add_one(struct ib_device *device)
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return;
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kref_init(&uverbs_dev->ref);
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init_completion(&uverbs_dev->comp);
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spin_lock(&map_lock);
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uverbs_dev->devnum = find_first_zero_bit(dev_map, IB_UVERBS_MAX_DEVICES);
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@ -793,6 +794,8 @@ err_cdev:
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err:
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kref_put(&uverbs_dev->ref, ib_uverbs_release_dev);
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wait_for_completion(&uverbs_dev->comp);
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kfree(uverbs_dev);
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return;
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}
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@ -812,7 +815,10 @@ static void ib_uverbs_remove_one(struct ib_device *device)
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spin_unlock(&map_lock);
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clear_bit(uverbs_dev->devnum, dev_map);
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kref_put(&uverbs_dev->ref, ib_uverbs_release_dev);
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wait_for_completion(&uverbs_dev->comp);
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kfree(uverbs_dev);
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}
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static int uverbs_event_get_sb(struct file_system_type *fs_type, int flags,
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