Re: [PATCH] svcrdma: avoid duplicate dma unmapping during error recovery

["J. Bruce Fields" <bfields@fieldses.org>]

On Mon, Jan 09, 2017 at 10:05:48AM -0500, Chuck Lever wrote:
> 
> > On Jan 9, 2017, at 1:42 AM, Yuval Shaia <yuval.shaia@oracle.com> wrote:
> > 
> > On Mon, Jan 09, 2017 at 04:00:44PM +0530, Sriharsha Basavapatna wrote:
> >> In rdma_read_chunk_frmr() when ib_post_send() fails, the error code path
> >> invokes ib_dma_unmap_sg() to unmap the sg list. It then invokes
> >> svc_rdma_put_frmr() which in turn tries to unmap the same sg list through
> >> ib_dma_unmap_sg() again. This second unmap is invalid and could lead to
> >> problems when the iova being unmapped is subsequently reused. Remove
> >> the call to unmap in rdma_read_chunk_frmr() and let svc_rdma_put_frmr()
> >> handle it.
> >> 
> >> Fixes: 412a15c0fe53 ("svcrdma: Port to new memory registration API")
> >> Cc: stable@vger.kernel.org
> >> Signed-off-by: Sriharsha Basavapatna <sriharsha.basavapatna@broadcom.com>
> >> Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
> >> ---
> >> net/sunrpc/xprtrdma/svc_rdma_recvfrom.c | 2 --
> >> 1 file changed, 2 deletions(-)
> >> 
> >> diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
> >> index 57d35fbb1c28..172b537f8cfc 100644
> >> --- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
> >> +++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
> >> @@ -347,8 +347,6 @@ int rdma_read_chunk_frmr(struct svcxprt_rdma *xprt,
> >> 	atomic_inc(&rdma_stat_read);
> >> 	return ret;
> >>  err:
> >> -	ib_dma_unmap_sg(xprt->sc_cm_id->device,
> >> -			frmr->sg, frmr->sg_nents, frmr->direction);
> >> 	svc_rdma_put_context(ctxt, 0);
> >> 	svc_rdma_put_frmr(xprt, frmr);
> >> 	return ret;
> > 
> > Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com>
> 
> Hi Bruce-
> 
> Is it possible to take this in v4.10-rc ?

Yep, thanks to all of you.--b.