re: RDMA/cxgb4: Support on-chip SQs

[Dan Carpenter <dan.carpenter-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>]

Hello Steve Wise,

The patch c6d7b26791a2: "RDMA/cxgb4: Support on-chip SQs" from Sep
13, 2010, leads to the following warning:
"drivers/infiniband/hw/cxgb4/qp.c:98 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
    92  static int alloc_host_sq(struct c4iw_rdev *rdev, struct t4_sq *sq)
    93  {
    94          sq->queue = dma_alloc_coherent(&(rdev->lldi.pdev->dev), sq->memsize,
    95                                         &(sq->dma_addr), GFP_KERNEL);
    96          if (!sq->queue)
    97                  return -ENOMEM;
    98          sq->phys_addr = virt_to_phys(sq->queue);
    99          pci_unmap_addr_set(sq, mapping, sq->dma_addr);
   100          return 0;
   101  }

This is a new Smatch check.  I don't know the rules on virt_to_phys yet
but here is the relevant comment.

/**
 *      virt_to_phys    -       map virtual addresses to physical
 *      @address: address to remap
 *
 *      The returned physical address is the physical (CPU) mapping for
 *      the memory address given. It is only valid to use this function on
 *      addresses directly mapped or allocated via kmalloc.
 *
 *      This function does not give bus mappings for DMA transfers. In
 *      almost all conceivable cases a device driver should not be using
 *      this function
 */

regards,
dan carpenter

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