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RDMA/core: Fix bogus WARN_ON during ib_unregister_device_queued() 

ib_unregister_device_queued() can only be used by drivers using the new
dealloc_device callback flow, and it has a safety WARN_ON to ensure
drivers are using it properly.

However, if unregister and register are raced there is a special
destruction path that maintains the uniform error handling semantic of
'caller does ib_dealloc_device() on failure'. This requires disabling the
dealloc_device callback which triggers the WARN_ON.

Instead of using NULL to disable the callback use a special function
pointer so the WARN_ON does not trigger.

Fixes: d0899892ed ("RDMA/device: Provide APIs from the core code to help unregistration")
Link: https://lore.kernel.org/r/0-v1-a36d512e0a99+762-syz_dealloc_driver_jgg@nvidia.com
Reported-by: syzbot+4088ed905e4ae2b0e13b@syzkaller.appspotmail.com
Suggested-by: Hillf Danton <hdanton@sina.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
zero-sugar-mainline-defconfig
Jason Gunthorpe 2020-06-26 14:49:10 -03:00
parent 65936bf25f
commit 0cb42c0265
1 changed files with 8 additions and 3 deletions
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11
drivers/infiniband/core/device.c
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@ -1339,6 +1339,10 @@ out:
return ret;
}
static void prevent_dealloc_device(struct ib_device *ib_dev)
{
}
/**
* ib_register_device - Register an IB device with IB core
* @device: Device to register
@ -1409,11 +1413,11 @@ int ib_register_device(struct ib_device *device, const char *name)
* possibility for a parallel unregistration along with this
* error flow. Since we have a refcount here we know any
* parallel flow is stopped in disable_device and will see the
* NULL pointers, causing the responsibility to
* special dealloc_driver pointer, causing the responsibility to
* ib_dealloc_device() to revert back to this thread.
*/
dealloc_fn = device->ops.dealloc_driver;
device->ops.dealloc_driver = NULL;
device->ops.dealloc_driver = prevent_dealloc_device;
ib_device_put(device);
__ib_unregister_device(device);
device->ops.dealloc_driver = dealloc_fn;
@ -1462,7 +1466,8 @@ static void __ib_unregister_device(struct ib_device *ib_dev)
* Drivers using the new flow may not call ib_dealloc_device except
* in error unwind prior to registration success.
*/
if (ib_dev->ops.dealloc_driver) {
if (ib_dev->ops.dealloc_driver &&
ib_dev->ops.dealloc_driver != prevent_dealloc_device) {
WARN_ON(kref_read(&ib_dev->dev.kobj.kref) <= 1);
ib_dealloc_device(ib_dev);
}