Function dma_alloc_coherent() returns a NULL pointer if there is no enough memory. Function ocrdma_mbx_create_ah_tbl() defined in file drivers/infiniband/hw/ocrdma/ocrdma_hw.c will return 0 on success or negative error codes on failures. It calls function dma_alloc_coherent() twice and checks the return values against NULL (at lines 1681 and 1686). The control flow jumps to label "mem_err_ah" and returns the value of variable status. The value of status is 0 (see the check of variable status at line 1645). As a result, the caller of ocrdma_mbx_create_ah_tbl() will be misled to believe all goes well even the memory allocation fails. Maybe it is better to assign "-ENOMEM" to variable status before the jump instructions at lines 1682 and 1687, or simply initialize status with "-ENOMEM" rather than "0" at line 1645. Codes related to this bug are summarised as follows.

ocrdma_mbx_create_ah_tbl @@ drivers/infiniband/hw/ocrdma/ocrdma_hw.c
1642 static int ocrdma_mbx_create_ah_tbl(struct ocrdma_dev *dev)
1643 {
1644     int i;
1645     int status = 0;  // use "int status = -ENOMEM;" ?
         ...
1653     cmd = ocrdma_init_emb_mqe(OCRDMA_CMD_CREATE_AH_TBL, sizeof(*cmd));
1654     if (!cmd)
1655         return status;
         ...
1678     dev->av_tbl.pbl.va = dma_alloc_coherent(&pdev->dev, PAGE_SIZE,
1679                         &dev->av_tbl.pbl.pa,
1680                         GFP_KERNEL);
1681     if (dev->av_tbl.pbl.va == NULL)
1682         goto mem_err;
1683 
1684     dev->av_tbl.va = dma_alloc_coherent(&pdev->dev, dev->av_tbl.size,
1685                         &pa, GFP_KERNEL);
1686     if (dev->av_tbl.va == NULL)
1687         goto mem_err_ah;
         ...
1706     return 0;
1707 
1708 mbx_err:
1709     dma_free_coherent(&pdev->dev, dev->av_tbl.size, dev->av_tbl.va,
1710               dev->av_tbl.pa);
1711     dev->av_tbl.va = NULL;
1712 mem_err_ah:
1713     dma_free_coherent(&pdev->dev, PAGE_SIZE, dev->av_tbl.pbl.va,
1714               dev->av_tbl.pbl.pa);
1715     dev->av_tbl.pbl.va = NULL;
1716     dev->av_tbl.size = 0;
1717 mem_err:
1718     kfree(cmd);
1719     return status;
1720 }

Thanks very much!