xprtrdma: Yet another double DMA-unmap
While chasing yet another set of DMAR fault reports, I noticed that
the frwr recycler conflates whether or not an MR has been DMA
unmapped with frwr->fr_state. Actually the two have only an indirect
relationship. It's in fact impossible to guess reliably whether the
MR has been DMA unmapped based on its fr_state field, especially as
the surrounding code and its assumptions have changed over time.
A better approach is to track the DMA mapping status explicitly so
that the recycler is less brittle to unexpected situations, and
attempts to DMA-unmap a second time are prevented.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Cc: stable@vger.kernel.org # v4.20
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 3ddba94..b9bc7f9 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -1329,9 +1329,12 @@ rpcrdma_mr_unmap_and_put(struct rpcrdma_mr *mr)
{
struct rpcrdma_xprt *r_xprt = mr->mr_xprt;
- trace_xprtrdma_mr_unmap(mr);
- ib_dma_unmap_sg(r_xprt->rx_ia.ri_device,
- mr->mr_sg, mr->mr_nents, mr->mr_dir);
+ if (mr->mr_dir != DMA_NONE) {
+ trace_xprtrdma_mr_unmap(mr);
+ ib_dma_unmap_sg(r_xprt->rx_ia.ri_device,
+ mr->mr_sg, mr->mr_nents, mr->mr_dir);
+ mr->mr_dir = DMA_NONE;
+ }
__rpcrdma_mr_put(&r_xprt->rx_buf, mr);
}