________________________________________
From: Steve Wise [sw...@opengridcomputing.com]
Sent: Thursday, July 17, 2014 8:31 PM
To: Devesh Sharma; Roland Dreier; Hefty, Sean
Cc: linux-rdma@vger.kernel.org; chuck.le...@oracle.com
Subject: Re: [for-next 1/2] xprtrdma: take reference of rdma provider module
On 7/17/2014 9:01 AM, Devesh Sharma wrote:
> If verndor driver is attempted for removal while xprtrdma still has an
> active mount, the removal of driver may never complete and can cause
> unseen races or in worst case system crash.
>
> To solve this, xprtrdma module should get reference of struct ib_device
> structure for every mount. Reference is taken after local device address
> resolution is completed successfuly.
>
> reference to the struct ib_device pointer is put just before cm_id
> destruction.
>
> Signed-off-by: Devesh Sharma <devesh.sha...@emulex.com>
This seems like an issue with the rdma-cm or rdma core, not xprtrdma. I
see that user rdma applications cause a ref on the provider module here
in ib_uverbs_open():
if (!try_module_get(dev->ib_dev->owner)) {
ret = -ENODEV;
goto err;
Maybe kernel applications that allocate device resources should cause a
ref on the provider's module.
Yes, To me it looks like the right place to get reference of provider driver is
rdma_resolve_addr()-->acuire_ib_dev(). However this patch provides a workaround.
Lets wait for Roland/Sean's input.
Sean/Roland, is there some history here as to how rdma provider module
removal should be handled?
Steve.
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