On 10/21/19 7:10 AM, Jason Gunthorpe wrote:
On Sun, Oct 20, 2019 at 07:10:28PM -0700, Bart Van Assche wrote:
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@xxxxxxxxx>
Cc: Ira Weiny <ira.weiny@xxxxxxxxx>
Cc: Adit Ranadive <aditr@xxxxxxxxxx>
Cc: Shiraz Saleem <shiraz.saleem@xxxxxxxxx>
Cc: Gal Pressman <galpress@xxxxxxxxxx>
Cc: Selvin Xavier <selvin.xavier@xxxxxxxxxxxx>
Fixes: d10bcf947a3e ("RDMA/umem: Combine contiguous PAGE_SIZE regions in SGEs")
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
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
+++ 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);
+ }
+ }
}
We really do want to, by default, increase the max_seg_size above 64k
though, so this approach doesn't seem right either.
How about replacing this patch by the patch below and by moving this patch to
the end of this series?
Thanks,
Bart.
Subject: [PATCH] RDMA/core: Set DMA parameters correctly
The dma_set_max_seg_size() call in setup_dma_device() does not have any
effect since device->dev.dma_parms is NULL. Fix this by initializing
device->dev.dma_parms first.
Cc: Michael J. Ruhl <michael.j.ruhl@xxxxxxxxx>
Cc: Ira Weiny <ira.weiny@xxxxxxxxx>
Cc: Adit Ranadive <aditr@xxxxxxxxxx>
Cc: Shiraz Saleem <shiraz.saleem@xxxxxxxxx>
Cc: Gal Pressman <galpress@xxxxxxxxxx>
Cc: Selvin Xavier <selvin.xavier@xxxxxxxxxxxx>
Fixes: d10bcf947a3e ("RDMA/umem: Combine contiguous PAGE_SIZE regions in SGEs")
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
---
drivers/infiniband/core/device.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
index a667636f74bf..a523d844ad9d 100644
--- a/drivers/infiniband/core/device.c
+++ b/drivers/infiniband/core/device.c
@@ -1199,9 +1199,21 @@ 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, so
+ * 'parent' probably represents a PCI device. The PCI
+ * core sets the maximum segment size to 64
+ * KB. Increase this parameter to 2G.
+ */
+ device->dev.dma_parms = parent->dma_parms;
+ dma_set_max_seg_size(device->dma_device, SZ_2G);
+ } else {
+ WARN_ON_ONCE(true);
+ }
+ }
}
/*
