[PATCH 2/4] RDMA/core: Set DMA parameters correctly

[Bart Van Assche <bvanassche@acm.org>]

The effect of the dma_set_max_seg_size() call in setup_dma_device() is
as follows:
- If device->dev.dma_parms is NULL, that call has no effect at all.
- If device->dev.dma_parms is not NULL, since that pointer points at
  the DMA parameters of the parent device, modify the DMA limits of the
  parent device.

Both actions are wrong. Instead of changing the DMA parameters of the
parent device, use the DMA parameters of the parent device if these
parameters are available.

Compile-tested only.

Cc: Michael J. Ruhl <michael.j.ruhl@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Adit Ranadive <aditr@vmware.com>
Cc: Shiraz Saleem <shiraz.saleem@intel.com>
Cc: Gal Pressman <galpress@amazon.com>
Cc: Selvin Xavier <selvin.xavier@broadcom.com>
Fixes: d10bcf947a3e ("RDMA/umem: Combine contiguous PAGE_SIZE regions in SGEs")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/infiniband/core/device.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
index 536310fb6510..b33d684a2a99 100644
--- a/drivers/infiniband/core/device.c
+++ b/drivers/infiniband/core/device.c
@@ -1199,9 +1199,18 @@ static void setup_dma_device(struct ib_device *device)
 		WARN_ON_ONCE(!parent);
 		device->dma_device = parent;
 	}
-	/* Setup default max segment size for all IB devices */
-	dma_set_max_seg_size(device->dma_device, SZ_2G);
 
+	if (!device->dev.dma_parms) {
+		if (parent) {
+			/*
+			 * The caller did not provide DMA parameters. Use the
+			 * DMA parameters of the parent device.
+			 */
+			device->dev.dma_parms = parent->dma_parms;
+		} else {
+			WARN_ON_ONCE(true);
+		}
+	}
 }
 
 /*
-- 
2.23.0