Re: Does ib_dereg_mr require an additional IB_WR_LOCAL_INV?

[Jason Gunthorpe <jgg@ziepe.ca>]

On Tue, Sep 23, 2025 at 11:09:48PM +0200, Stefan Metzmacher wrote:
> Hi,
> 
> I'm trying to understand (and hopefully simplify) the code in fs/smb/client/smbdirect.c,
> related to 'struct ib_mr' cleanup on disconnect.
> 
> Assume we have the following sequence of calls:
> 
> ...
> ib_alloc_mr()
> ib_dma_map_sg()
> ib_map_mr_sg()
> ib_post_send(IB_WR_REG_MR)
> 
> On cleanup we currently us something like this:
> 
> ib_drain_qp()
> init_completion()
> ib_post_send(IB_WR_LOCAL_INV)
> wait_for_completion()...
> ib_dereg_mr()
> ib_drain_qp() // again
> rdma_destroy_qp();
> ib_destroy_cq(revc_cq)
> ib_destroy_cq(send_cq)
> ib_dealloc_pd()
> rdma_destroy_id()
> 
> Now I'm wondering if the following is really required:
> init_completion()
> ib_post_send(IB_WR_LOCAL_INV)
> wait_for_completion()...

I would say IB_WR_LOCAL_INV is redundent with the ib_dereg_mr(). There
is no need to invalidate something that will be de-registered in a few
moments.

Jason