forked from Minki/linux
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>
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@ -117,15 +117,15 @@ static void
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frwr_mr_recycle_worker(struct work_struct *work)
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{
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struct rpcrdma_mr *mr = container_of(work, struct rpcrdma_mr, mr_recycle);
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enum rpcrdma_frwr_state state = mr->frwr.fr_state;
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struct rpcrdma_xprt *r_xprt = mr->mr_xprt;
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trace_xprtrdma_mr_recycle(mr);
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if (state != FRWR_FLUSHED_LI) {
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if (mr->mr_dir != DMA_NONE) {
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trace_xprtrdma_mr_unmap(mr);
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ib_dma_unmap_sg(r_xprt->rx_ia.ri_device,
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mr->mr_sg, mr->mr_nents, mr->mr_dir);
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mr->mr_dir = DMA_NONE;
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}
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spin_lock(&r_xprt->rx_buf.rb_mrlock);
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@ -150,6 +150,8 @@ frwr_op_init_mr(struct rpcrdma_ia *ia, struct rpcrdma_mr *mr)
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if (!mr->mr_sg)
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goto out_list_err;
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frwr->fr_state = FRWR_IS_INVALID;
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mr->mr_dir = DMA_NONE;
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INIT_LIST_HEAD(&mr->mr_list);
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INIT_WORK(&mr->mr_recycle, frwr_mr_recycle_worker);
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sg_init_table(mr->mr_sg, depth);
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@ -1329,9 +1329,12 @@ rpcrdma_mr_unmap_and_put(struct rpcrdma_mr *mr)
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{
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struct rpcrdma_xprt *r_xprt = mr->mr_xprt;
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if (mr->mr_dir != DMA_NONE) {
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trace_xprtrdma_mr_unmap(mr);
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ib_dma_unmap_sg(r_xprt->rx_ia.ri_device,
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mr->mr_sg, mr->mr_nents, mr->mr_dir);
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mr->mr_dir = DMA_NONE;
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}
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__rpcrdma_mr_put(&r_xprt->rx_buf, mr);
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}
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