Re: use exact allocation for dma coherent memory

Dan Carpenter
2019-06-17T08:21:48Z

I once wrote a Smatch check based on a commit message that said we can't
pass dma_alloc_coherent() pointers to virt_to_phys(). But then I never
felt like I understood the rules enough to actually report the warnings
as bugs.

drivers/platform/x86/dcdbas.c:108 smi_data_buf_realloc() error: 'buf' came from dma_alloc_coherent() so we can't do virt_to_phys()
drivers/net/caif/caif_virtio.c:414 cfv_create_genpool() error: 'cfv->alloc_addr' came from dma_alloc_coherent() so we can't do virt_to_phys()
drivers/infiniband/hw/cxgb4/qp.c:135 alloc_host_sq() error: 'sq->queue' came from dma_alloc_coherent() so we can't do virt_to_phys()
drivers/infiniband/hw/cxgb4/qp.c:272 create_qp() error: 'wq->rq.queue' came from dma_alloc_coherent() so we can't do virt_to_phys()
drivers/infiniband/hw/cxgb4/qp.c:2628 alloc_srq_queue() error: 'wq->queue' came from dma_alloc_coherent() so we can't do virt_to_phys()
drivers/infiniband/hw/ocrdma/ocrdma_verbs.c:494 ocrdma_alloc_ucontext() error: 'ctx->ah_tbl.va' came from dma_alloc_coherent() so we can't do virt_to_phys()

drivers/infiniband/hw/cxgb4/qp.c
129 static int alloc_host_sq(struct c4iw_rdev *rdev, struct t4_sq *sq)
130 {
131 sq->queue = dma_alloc_coherent(&(rdev->lldi.pdev->dev), sq->memsize,
132 &(sq->dma_addr), GFP_KERNEL);
133 if (!sq->queue)
134 return -ENOMEM;
135 sq->phys_addr = virt_to_phys(sq->queue);
136 dma_unmap_addr_set(sq, mapping, sq->dma_addr);
137 return 0;
138 }

Is this a bug?

regards,
dan carpenter

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